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APPLICATIONS OF GEOGRAPHIC INFORMATION SYSTEMS (GIS)
FOR HIGHWAY TRAFFIC NOISE ANALYSIS

Case Studies of Select Transportation Agencies

November 2012

Prepared for:
Office of Planning
Federal Highway Administration
U.S. Department of Transportation		 seal of the U.S. Department of Transportation   Prepared by:
Organizational Performance Division
John A. Volpe National Transportation Systems Center
Research and Innovative Technology Administration
U.S. Department of Transportation		 The Volpe Center logo

TABLE OF CONTENTS

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ACKNOWLEDGMENTS

The U.S. Department of Transportation John A. Volpe National Transportation Systems Center (Volpe Center) in Cambridge, Massachusetts, prepared this report for the Federal Highway Administration's (FHWA) Office of Planning. The project team included Alisa Fine of the Volpe Center's Organizational Performance Division and Jaimye Bartak of Cambridge Systematics.

The Volpe Center project team wishes to thank the staff members from several organizations nationwide, each listed in Appendix A, for providing their experiences, insights, and editorial review. The time they kindly provided was vital in preparing the case studies and drafting this final report.

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EXECUTIVE SUMMARY

Noise from highway traffic can be pervasive in areas near roadways. How and to what extent noise travels is strongly influenced by geospatial features such as terrain and elevation. Thus geographic information systems (GIS), which enable users to more easily manage, analyze, and present geospatial information, can help transportation agencies evaluate noise impacts from highway traffic and identify noise mitigation options.

There is great potential in applying GIS for highway traffic noise analysis, but its use is still evolving nationwide. To explore how transportation agencies are applying GIS to highway noise analysis, the Federal Highway Administration (FHWA) sponsored a peer exchange on April 23-24, 2012, in Nashville, Tennessee. The peer exchange convened eight State Departments of Transportation (DOTs) that have made progress in using GIS to better understand noise considerations. Prior to the peer exchange, the Volpe Center, in coordination with FHWA, conducted telephone discussions with the peer exchange State DOTs to better understand how agencies are developing GIS tools and applying geospatial data to meet noise program objectives. Case studies summarizing these DOTs' efforts were then developed.

This report, which synthesizes these case studies to describe overall observations, is expected to support GIS and noise practitioners to identify examples of noteworthy practices, consider the pros and cons of GIS applications for noise, and determine how these applications might be best utilized. In general, observations suggest that:

In summary, while the use of GIS for highway traffic noise is still a developing area, State DOTs are currently using a variety of GIS tools and geospatial data from multiple sources to accomplish noise objectives. On the whole, State DOTs believed that these applications, while sometimes challenging to develop and use, led to important benefits such as streamlining responses to Federal mandates and more effective stakeholder communication.

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1. INTRODUCTION

This section provides an overview of the purpose of this research effort and methodology used, as well as details on the Federal noise legislation that provides a basis for agencies' GIS for noise analysis work. This section also provides background information on how applications of GIS for noise analysis fit into the broader context of using GIS to meet transportation needs.

Purpose

Sounds are vibrations in the air that reach the ear. Noise, on the other hand, is unwanted or excessive sound.1 Unique features associated with a particular space, such as terrain, vegetation, elevation, and land uses, all influence the dynamics of sound, and as an extension, noise. Thus both sound and noise are inherently geospatial issues. Furthermore, highway traffic can be a dominant and pervasive source of noise in both urban and rural environments. GIS, which enables users to more easily manage, analyze, and present geospatial information, can help transportation agencies conduct noise analyses, including assessing how highway traffic will affect noise levels and identifying noise mitigation options.

To explore this topic in depth, Federal Highway Administration (FHWA) and the Volpe National Transportation Systems Center (Volpe Center) conducted a series of telephone discussions and sponsored a peer exchange in Nashville, Tennessee, focusing on select State DOTs' use of GIS in highway noise analysis.

The purpose of the discussions and peer exchange was to allow State DOTs with experience in incorporating GIS into highway noise applications and activities the opportunity to:

The use of GIS in noise analysis is relatively new. This effort convened noise and GIS specialists to discuss the burgeoning intersection of GIS and noise expertise, a dialogue that may not have previously occurred on a regular basis among the selected States. Furthermore, in light of a July 2011 update of Federal noise regulations, the interviews and peer exchange also provided an opportunity for practitioners to discuss new approaches for using GIS to address Federal mandates.

By hosting peer exchanges and supporting other research and activities focused on a variety of topics, FHWA seeks to facilitate opportunities for States to gain knowledge from others' successes and challenges in the application of GIS.2 Furthermore, FHWA shares resources that can support agencies' use of GIS (see Appendix D for a list of resources).

Methodology

State DOTs were selected for participation based on their activity as part of the Transportation Research Board's Committee on Transportation-Related Noise and Vibration (ADC40). While the selected State DOTs varied widely in their approaches to using GIS to support noise analysis, all had demonstrated progress in this area.

Participants included noise and/or GIS staff from the California Department of Transportation (Caltrans), Florida DOT (FDOT), Maryland State Highway Administration (MDSHA), North Carolina DOT (NCDOT), Ohio DOT (ODOT), Tennessee DOT (TDOT), Virginia DOT (VDOT), and Washington DOT (WSDOT). Appendix A includes a complete list of participants. An interview guide provided a framework for the telephone discussions conducted prior to the peer exchange (see Appendix B for the guide). Each discussion lasted approximately 60 to 90 minutes. Case studies were drafted based on participant responses during these discussions. A set of draft case studies was distributed to participants as background material ahead of the peer exchange.

The peer exchange, which TDOT hosted at its offices in downtown Nashville, took place on April 23-24, 2012. During the peer exchange, FHWA presented its perspectives on the benefits of applying GIS to noise analysis. FHWA believes that GIS, use of geospatial data, and other geospatial tools (e.g., remote sensing) can help transportation officials make better decisions.

Following FHWA's presentation during the peer exchange, State DOTs demonstrated their current uses of GIS and geospatial data to support their respective noise analyses. Four roundtable discussions also provided opportunities for dialogue. These roundtables focused on topics of interest identified from the telephone discussions, including: (1) using GIS for noise reporting (sound wall inventories); (2) collecting noise-relevant data; (3) applying GIS/geospatial data to assess noise; and (4) assessing the potential of GIS in noise assessments. Appendix C provides a list of questions discussed during the roundtables.

Appendix E provides a cumulative look at all applications of GIS discussed during the telephone discussions and peer exchange as well as how these applications are used.

Background

The Federal-Aid Highway Act of 1970 includes mandates for how FHWA must regulate and mitigate highway traffic noise. FHWA codified its regulations in Title 23 CFR, Part 772: Procedures for Abatement of Highway Traffic Noise and Construction Noise.3 The regulation, which applies to any highway project that receives Federal funding, was updated in July 2011 to provide additional guidance that reflected feedback received from State DOTs and professional practitioners.

The regulation also updated definitions of key noise terms. Terms used frequently in this report include the following:

Highlights of July 2011 Updates to
23 CFR 772:

The update of 23 CFR 772 formalized reporting requirements. State DOTs must provide to FHWA (on a triennial basis) inventories that include information on any constructed noise abatement measure, including cost, height, length, location, year of construction, and materials used in construction. See Appendix F for the complete list of data required in these noise wall inventories.

Furthermore, DOTs must use FHWA's TNM in their traffic noise prediction analysis for all projects subject to 23 CFR 772.The FHWA TNM is a state-of-the-art, three-dimensional model that calculates traffic noise levels and noise level reductions based on user input of roadways, barriers, terrain features such as hills, valleys, woods and lakes; structures, and traffic data. It uses advances in personal computer hardware and software to improve upon the accuracy and ease of modeling highway noise, including the design of effective, cost efficient highway noise barriers. Modeling a location requires a significant amount of data including topography, the physical characteristics of the existing noise barrier, traffic volumes, and mix and speed of the adjacent highway.5

While neither 23 CFR 772 nor TNM require the use of GIS, many States have turned to GIS to facilitate compliance with 23 CFR 772 and use of TNM, as well as to support noise analyses.

The capabilities of GIS in the transportation arena are well documented.6 However, there is still unexplored potential for using GIS to support highway traffic noise analysis. Existing research primarily focuses on technical requirements associated with GIS-based noise modeling.7 There is currently little research on how GIS can support other noise activities, such as in compiling noise wall inventories. Little documentation exists on the lessons learned, success factors, and challenges experienced by transportation agencies using GIS to address highway traffic noise, as well as the steps agencies took in developing discrete GIS tools focused on noise.

Most of the agencies participating in this research effort are still investigating how to most effectively develop GIS tools for noise or utilize geospatial data for noise analysis. Resources for noise programs can be limited, complicating agencies' efforts to initiate or expand their uses of GIS in the noise discipline. Typically, noise programs at State DOTs are comprised of fewer than three staff persons and many programs have worked extensively with consultants to collect noise-related geospatial data. GIS and noise specialists within the same agency may not have regular opportunities to coordinate and discuss GIS solutions to support noise analysis.

Despite these challenges, some State DOTs have found innovative ways to use GIS and geospatial data, finding that GIS can support many aspects of noise analysis, including meeting the requirements of 23 CFR 772 (particularly its reporting requirements). As agencies experience successes in these areas, these accomplishments will likely provide good foundations for subsequent advancements.

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2. OBSERVATIONS

This section describes overall observations in how select State DOTs are using GIS to analyze the potential effects and impacts of highway noise, as well as the associated benefits, challenges, and lessons learned resulting from these experiences.

State of the Practice

The use of GIS to support noise analysis is evolving nationwide. The recent update to 23 CFR 772 has spurred some State DOTs to initiate or re-consider the use of better or emerging GIS technologies to access geospatial data in new ways than in the past.

Benefits

State DOTs reported a number of benefits related to uses of GIS for noise analysis, particularly in terms of streamlining communication with diverse stakeholders, making noise analyses more efficient and cost-effective, supporting better coordination, and fostering more effective decision-making.

Challenges

State DOTs have demonstrated creativity in developing a variety of innovative GIS applications and tools for noise analysis. However, given the nascent nature of the state of the practice, State DOTs have experienced some challenges in developing these activities, including:

Potential Advancements for GIS in Highway Traffic Noise Analysis

As State DOTs discussed the future of their noise programs, they commonly noted several promising and desired advancements that geospatial data and tools could achieve within the practice of noise analysis, including:

Lessons Learned

State DOTs that have used GIS for noise analysis indicated that their efforts typically began in a piecemeal fashion, applying GIS and geospatial data to address various issues as they arose and gradually expanding GIS use. In hindsight, State DOTs have identified both successful approaches and missed opportunities to help inform the further integration of GIS. Lessons learned include:

Areas for FHWA Support

In addition to the above lessons learned, State DOTs mentioned several ways in which FHWA could support efforts to incorporate GIS and geospatial data into noise analysis activities.

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3. CASE STUDIES

This section presents in-depth case studies on the current activities of the State DOTs that participated in interviews and the peer exchange. Each case study includes information on how the agency began using GIS or geospatial data to support noise analysis activities, how it developed noise analysis GIS tools, and the challenges, lessons learned, and benefits encountered while utilizing their respective tools.

3.1 California Department of Transportation (Caltrans)

Caltrans used GIS to develop a web-based "Statewide Sound Wall Inventory" and mapping application.

Background
California has an estimated 750 miles of noise walls. Due to the large number of noise walls distributed across such a large State, Caltrans sometimes struggled to coordinate and maintain its sound wall inventory among its 12 districts and 22,000 employees.

To help address this issue, Caltrans identified GIS in 2009 as a way to incorporate a large range of data. Using GIS, Caltrans compiled sound wall information into a GIS-based inventory. Information from the inventory was previously compiled in Excel spreadsheets. The overall intent of developing the inventory was to respond to the reporting requirements of 23 CFR 772, but over time the tool has helped support broader decision-making related to the sound walls.

The inventory was converted into an interactive, web-based tool that assists users in visualizing noise walls and any issues associated with them. The tool is accessible to all Caltrans' districts and the public at https://dot.ca.gov/programs/environmental-analysis (see Figure 1).

Screenshot of Caltrans' Online Statewide Sound Wall Inventory showing a map of the greater Los Angeles area with three visible layers: Statewide Soundwall Inventory, California Roads, and Caltrans Districts Boundaries Figure 1. Screenshot of Caltrans' Online Statewide Sound Wall Inventory.

Developing the Sound Wall Inventory
The overall purpose of the inventory was to provide a "one-stop shop" for obtaining information on the location of sound walls and their attributes, including their length, location, and construction costs. The inventory also provides users with an easy way to visualize noise walls and conduct queries. Because Caltrans' districts each have their own GIS applications, some of which include noise data, there is no centralized repository that stores all of Caltrans' GIS noise data. In developing the inventory, Caltrans sought to provide a more consistent way to store and communicate information on noise walls.

The inventory, which one staff member built, uses ESRI's FlexViewer template, a tool available for free online and designed to be used in conjunction with an ArcGIS server.12 FlexViewer is customizable, user-friendly software that enables users to create online mapping applications.

To develop the tool, Caltrans staff georeferenced information from Excel-based spreadsheets at a cost of approximately $12,000 including the cost of GIS software, maintenance fees, and labor. Additional information was obtained through requests to Caltrans' districts, Google Maps, or from site visits by district staff when possible. Caltrans's existing GIS-based maps (streets, aerials, and topography) were also imported into the tool. Type II sound walls were not included since they are restricted to local funding.

In addition to sound wall data, the inventory also contains air quality and school data. The latter are included due to a State regulation that transportation project noise levels in proximity to schools must be minimized.

Noise wall attributes within the inventory are linked to QuickTime videos of five-mile sections of the barriers. These videos were created as part of the Caltrans' previously conducted video inventory of all State highways. Adding video to the inventory took a few weeks.

Currently, the inventory is referenced when staff members respond to noise complaints or when existing walls need to be identified, for instance, when adding lanes to a highway. While Caltrans does not yet utilize GIS in conjunction with TNM, Caltrans notes the inventory will be useful in determining the elevation of sound walls as part of noise modeling for paving or other highway expansion projects. The inventory is not currently being used during project screening or scoping phases.

Sound Wall Inventory Data
Caltrans recognizes that there are some information gaps in the existing inventory and has estimated data points for some attributes, such as wall length and location. Many of the data gaps are related to attributes for as-built walls. This is because older as-built information was discarded and there is currently no system in place for Caltrans to automatically receive as-built information from its districts. However, Caltrans is working on developing a system to obtain elevations for constructed sound walls and heights from districts once projects are completed.

Wall cost data are also difficult to obtain due to California's procurement process. Engineering estimates provide a range for wall costs, but bids for noise walls are made based on sound wall material unit costs, often for multiple walls at once. Yet, what is needed to respond to 23 CFR 772 is the cost of the sound wall per square foot. To date, Caltrans has been able to make estimates of what the noise walls actually cost to construct by comparing bids to actual unit costs, though it recognizes a future need for more accurate noise wall cost data. Collecting such information would be time-intensive, however, as it would require searching each district's database.

In the future, Caltrans would like to include noise contours and cumulative noise exposure data from airports in the inventory, should these be developed (the city of San Francisco has such information, including stationary sources with contours). Caltrans would ideally like to have contour data from across the State with 500' intervals; however, such a large undertaking is unlikely given current funding and staffing constraints. As an alternative, some cities may be willing to provide Caltrans with their noise data.

Another potential use of the inventory could be determining how different pavement types used for highway rehabilitations will affect noise impacts, but these data are currently not included in the inventory. Caltrans views pavement types as a desirable, though potentially difficult to obtain, addition to its GIS database. Caltrans also intends to explore whether LiDAR data might be available within its organization to help further verify existing sound wall data.

Benefits
Overall, the inventory's benefit to Caltrans is in allowing staff to conduct more accurate and efficient spatial analyses and providing a more comprehensive understanding of what walls exist and where they are located. This information supports decision-making on noise abatement measures, such as identifying where building a wall will be most cost-effective. Caltrans has also found the tool useful to obtain elevation information.

The inventory also supports more effective information sharing. A selected view or extent can be bookmarked and shared with another user. Users can also perform detailed queries; mousing over results will reveal an attribute table that contains more information on the noise walls. Each attribute table contains a link to a Google map from which users can select a "street view" if desired. The Google map is also embedded with a marker that will launch the corresponding video of the road when clicked. Data within the tool can be saved locally on a computer, or exported for use in reports.

Lessons Learned
Caltrans identified the following lessons learned in developing its GIS noise wall inventory:

3.2 Florida Department of Transportation (FDOT)

Background
In 2001, FDOT and 23 other State, Federal, and local agencies, as well as several Tribal Nations developed the Efficient Transportation Decision Making (ETDM) process. These agencies and Tribal governments form Environmental Technical Advisory Teams (ETAT) for each of FDOT's seven geographic districts. ETDM provides a framework for FDOT, the ETAT, and the public to identify potential environmental impacts of transportation projects beginning at the earliest planning stages. The ETDM process promotes early coordination and transparent communication that leads to better issue definition, leading to a reduction in the amount of unforeseen, late-stage events that can affect project schedules and budgets.

FDOT uses GIS in the noise discipline to:

FDOT's Central Environmental Management Office provides oversight of FDOT's noise program in regards to rules and procedures for all noise analyses in the State. Administrators in each of FDOT's seven districts and turnpike authority oversee the actual implementation of all projects located within their areas. Each of FDOT's Districts has a noise specialist who works with its own consultant team to complete and review noise assessments.

The ETDM process is implemented using the EST, a web-based, GIS application14 that contains all comments and information related to screened projects and over 550 environmental resource GIS data layers, including over 25 that are noise-related. ETATs review and comment on proposed transportation projects within the EST according to their agencies' respective statutory and regulatory authority. The public can also access the EST and use the tool to stay updated on projects of interest.

FDOT and environmental agencies use the EST to address noise issues early on in the project planning and programming phases. Noise is one of 21 issues considered during these phases, with noise impacts reviewed in regards to their relationship with population centers, land use, proximity to existing noise walls, and proximity to noise sensitive facilities like hospitals. Standard noise modeling analyses are conducted on transportation projects after the planning and programming phases, during the project development and environment (PD&E) phase. Currently, FDOT does not incorporate geospatial data into the TNM process as part of PD&E.

FDOT is in the early stages of updating its GIS noise wall inventory to respond to 23 CFR 772's reporting requirements and other internal and external requests for noise wall information. All GIS layers are stored within the Florida Geographic Data Library (FGDL), a comprehensive database at the University of Florida's GeoPlan Center.

Assessing Noise in the ETDM Process
Given the impact noise walls have on project costs and schedules, FDOT saw value in considering noise early in the project delivery process. Prior to 2012, however, noise considerations and comments were provided under EST's aesthetic issue. Under this arrangement, however, noise was not always fully addressed, so FDOT decided to treat noise as a stand-alone issue within the EST to better highlight its importance. Noise impact considerations within the EST primarily consider the community's perception of possible noise impacts because project alignment details at this stage are still too fluid to conduct an analysis in terms of physical impacts. Predictive modeling does not take place until later stages.

The ETDM process consists of three phases: planning, programming, and project development and environment (PD&E) (see Figure 2). During the Planning and Programming Phases, projects are reviewed in the EST. The reviews, also known as screening events, last 45 to 60 days and are initiated through EST-generated email notifications. The Planning and Programming Screens apply only to qualifying capacity improvement projects as outlined in the ETDM Manual and include such projects as the widening of roadways, new roadways, new rail systems, and bridge projects. The issues that agencies are expected to comment on during each screening are specified in the Agency Operating Agreement that exists between the agency, FDOT, and FHWA. FDOT and metropolitan planning organizations (MPOs) are responsible for sociocultural effects evaluations. FDOT, MPOs, and FHWA are the only agencies expected to comment on noise issues, though other agencies may elect to comment as well.

Flowchart of the ETDM process, showing the three major phases: Planning Phase, Programming Phase, and Project Development and Environment Phase Figure 2. ETDM Process (courtesy of FDOT).

Planning Screen
Comments collected from ETAT during the planning screen assist FDOT and MPOs in determining the feasibility of proposed projects for inclusion in their long-range transportation plans (LRTPs). Reviews and comments at this stage are cursory and provide the project sponsor with a general understanding of the project's purpose and need and affected environment (e.g., the presence of noise vibration sensitive facilities). The project sponsor uses this feedback to acquire a better sense of the proposed project's viability and any critical flaws with the project or a particular alternative. FDOT then revises project concepts to reflect feedback and cost feasibility concerns. Early avoidance or minimization efforts may seek, for example, route modifications that minimize the need for noise walls. Projects then await prioritization by FDOT and MPO management before moving into the programming phase.

Programming Screen
During the Programming screen, projects are under consideration for inclusion in the FDOT Work Program. The Programming screen builds upon the information produced during the Planning Phase by identifying potential avoidance, minimization, and mitigation opportunities and refining or potentially eliminating alternatives, as applicable. The Programming screen initiates the National Environmental Policy Act (NEPA) project scoping process for projects with Federal funding/action. The Programming screen specifically involves soliciting more detailed feedback from agencies and partners in order to determine the necessary environmental document (e.g., Environmental Impact Statement (EIS)) and associated technical studies and permits. FDOT can then use this information to estimate project costs and the project timelines. During this phase, FDOT considers noise in terms of the community's perception and identifies the likely impact on noise-sensitive receptors located in the project area. Noise assessments look at the specific character and environmental context of the project and not just on traffic volume.

PD&E Screen
Finally, the PD&E phase involves using the information generated during the earlier programming screen to prepare the necessary studies and reports needed to accompany the corresponding environmental document (EIS, Environmental Assessment, etc.) that must be developed for the project. At this stage, the range of project alternatives has been defined, making detailed noise analysis appropriate. Also, during this stage, the ETAT will provide technical assistance upon request by FDOT.

Using the EST
Data in the EST are organized by issues such as farmland or noise. A number of mapping tools and imagery datasets are available to support the analysis process. This includes common mapping application tools such as queries and buffers as well as more unique functions such as Google's Street View (see Figure 3) and an FDOT video log of State-owned roadways. Various aerial imagery datasets are also available, including one-foot resolution digital orthophoto imagery from 2009 or later. FDOT can customize the EST's data to accommodate agency partners' respective reviews. Staff at the GeoPlan Center work with the ETAT to obtain/update existing data layers or to develop new layers. Data-update cycles are layer-dependent, but FDOT works to ensure the most recent dataset is always available.

Screenshot of the Google Street View Integration with the Map Viewer showing a photograph of a street imposed over a map Figure 3. Google Street View Integration with the Map Viewer.
EST Screenshot showing a map of the area around Green Cove Springs with color-coded roads Figure 4. Screenshot of EST.

When resource agencies and partners log in to the EST, they can review a project's purpose and need, description, and associated GIS analysis results. The map interface is customizable and users have the flexibility to determine which issues and project alternatives are visible. Users can also select buffer zones ranging from 100 feet to 5,280 feet (1 mile) to see what data features fall within the specified range of the project.

Overall, considering noise early on in the planning process has led to cost savings and better project outcomes since the potential need for noise walls can be identified before funding is committed to a project. ETDM enables FDOT to resolve or mitigate particular noise issues early on in project development. Identifying a noise issue late can lead to increased project costs and potentially add time to the production delivery schedule.

Future Steps
Because analyzing noise as a stand-alone issue is relatively new, FDOT is still identifying data gaps and potential sources of new noise information to add to the EST.

In the future, FDOT intends to fully update and expand its 2005 noise wall GIS database and has begun to identify the attributes that will be captured. Once the new geodatabase is developed, it will replace the current noise wall GIS database within the EST and also include an automated data reporting system to satisfy information requests related to noise walls. FDOT hopes this noise wall inventory database can be developed in partnership with other FDOT offices that could stand to benefit, such as FDOT's Maintenance Office.

FDOT also noted that they are interested in investigating opportunities to develop future datasets for inclusion in the EST, such as:

3.3 Maryland State Highway Administration (MDSHA)

Background
MDSHA's Office of Planning and Preliminary Engineering (OPPE) and the Office of Highway Development share duties related to the highway noise program in Maryland as the result of a reorganization effort in 2008.

MDSHA uses GIS in the noise discipline to:

Currently, the Noise Abatement Design and Analysis Team (NADAT) in OPPE is responsible for technical and policy guidance related to noise, review, and approval of all Type I highway noise studies under NEPA, community noise studies, and noise barrier acoustical design (for Type II barriers). There are three staff members within OPPE working on noise issues: the NADAT team leader, an Environmental Planning Division noise specialist, and supplemental consultant support.

Since its noise program started in 1977, MDSHA has compiled numerous noise data that were in multiple formats, both paper and electronic. These data included noise complaints, community noise impact studies, community highway and development histories/build dates (for Type II analysis), NEPA analyses, after-studies of barrier effectiveness, and inventories of completed Type I and Type II barriers.

Before moving to GIS, most noise-related archiving activities utilized ProjectWise.15 Over time, MDSHA identified a need for a centralized repository for disparate information that could be accessed by leadership and users in multiple departments. Until recently, however, there was no strong GIS platform available to which information could be contributed. Recently MDSHA developed an enterprise GIS web application called MD iMap,16 which consolidates all information the agency uses in its transportation programs and decision-making.

NADAT has started preparing and contributing noise-related information, including a noise wall inventory, to MD iMap by focusing on the extraction and organization of data elements related to NEPA noise studies, archiving old studies and reports, and compiling independently-developed databases and inventories. This effort is expected to provide a cohesive and complete information system for the highway noise program in Maryland.

Noise Wall Inventory
Concurrent with its efforts to prepare and contribute noise data to MD iMap, MDSHA hired a consultant to compile an inventory of every noise barrier and its location data in the State, as well as to take multiple photographs of each barrier. The consultant also "field verified" data found in existing records and collected global positional system (GPS) coordinate data at critical locations along the barrier alignment, as well as at locations of design elements such as fire hose connections or maintenance doors. During this process, the consultant incorporated and field-verified other data on the barriers, such as materials used, surface textures and finishes, physical condition/damage, and physical dimensions (wall length and height).

A large portion of these data had been compiled and maintained over the course of the highway noise program, but they were stored in disparate formats and locations. The 2010 effort to compile a comprehensive inventory was able to incorporate many of these older data. For example, the MDSHA Office of Structures developed an inventory of all "small structures," which gathered information on retaining walls, headwalls, culverts, and noise barriers within a searchable database. Georeferencing was not part of this original effort, though each item was assigned a structure number. These data were ultimately combined and incorporated into the noise wall inventory, with the structure numbers serving as the common data element. Information was verified with reference to a PDF archive of past as-built plans for projects with noise barriers.

Once completed, the inventory went through a review process to check for redundancies with other datasets and for quality control purposes. MDSHA aims to complete verification of the georeferencing and proceed with integration of the inventory into MD iMap soon. In the meantime, MDSHA has increasingly relied on Google Maps—particularly its aerial information—when responding to noise-related inquiries from the public or other MDSHA departments, district offices, or local government agencies.

To date, the main benefit of the inventory has been providing inspection and maintenance tracking and a data source for program-level reporting to FHWA and within MDSHA. The completed inventory has also been useful when responding to inquiries from the public, elected officials, and resource agencies.

The total cost of compiling and updating the noise wall inventory has likely been between $100,000 and $200,000, though MDSHA has not estimated the accumulated total costs over the years.

Separate from the noise wall inventory, MDSHA has also maintained a noise complaint inventory comprised of State grid maps with colored dots (a "manual GIS") to define where complaints had been received, letters written, and studies performed. Some complaint data has been converted into electronic databases but has not been georeferenced. There is a less urgent need for regular access to geocoded noise complaints, especially given other available tools such as Google Maps. This is also because all Type II projects identified in the original candidate list from the late 1970s have been constructed and a finite number of potential future Type II projects exist based on MDSHA and FHWA eligibility criteria. The complaints MDSHA receives now are somewhat more irregular, and less likely to involve extended coordination (i.e., not from the same neighborhood). In the past, prior to building the complaint inventory, MDSHA would reference noise complaint maps to see if complaints had been received; multiple individual or repeated inquiries often signified that an area was a strong candidate for a Type II noise barrier.

Future Steps
When all existing noise walls are fully geocoded and integrated into MD iMap, MDSHA envisions expanding the inventory to include proposed walls. GIS would support this effort by outlining geographic relationships between noise receptors, impacted communities, project boundaries, and environmental features. MDSHA is also considering incorporating environmental noise data about planned projects into MD iMap to keep a record of projects and to support reevaluations in the future. This would help provide a useful reference when potential projects are considered or in some cases reactivated after many years.

In the future, MDSHA may also link the inventory to a photolog application used elsewhere in MDSHA called "Visidata." If linked with the inventory, Visidata would allow users to view existing pictures of noise walls or communities. MDSHA also has a video log that could potentially be linked to the noise barrier inventory in MD iMap.

MDSHA does not currently use GIS as part of its TNM noise modeling process but may do so in the future.

Lessons Learned
MDSHA reported the following lessons learned:

3.4 North Carolina Department of Transportation (NCDOT)

Background
NCDOT recently overhauled and updated its traffic noise abatement and modeling policies in accordance with 23 CFR 772. This overhaul included adopting GIS as a regular tool to support noise analyses in responding to significantly shorter project cycles.17 Prior to 2010, NCDOT's noise assessments generally consisted of using simple distance and source-emission equations and flat and level models, which NCDOT notes sometimes under-assessed noise abatement criteria (NAC)18 impacts. The only GIS data used to support noise analysis were parcels and existing local roadways. With GIS capabilities now in place, NCDOT considers its noise program to be more formalized and proficient, as well as more beneficial to the public in terms of technical assessment and cost-effectiveness.

NCDOT uses GIS for noise analysis to support:

NCDOT's progress in using GIS has been aided by several statewide initiatives and NCDOT's own leadership. Agencies in North Carolina have access to statewide LiDAR data, with 12-inch to 18-inch resolution, as well as a central repository for statewide GIS data collected from State and local agencies. NCDOT leadership has advanced the noise program through its stated recognition that noise walls should not be designed as part of the roadway, but rather as part of the community. NCDOT leadership also worked to ensure that contracts with consultants included provisions that required the submittal of all data collected for a project, rather than just for analyses or reports, which has helped expand the agency's data library.

NCDOT's traffic noise analyses, abatement design, and public outreach are performed by four in-house staff members and several on-call consulting firms. The noise team works independently of NCDOT's GIS staff but relies on the GIS expertise when available, since virtually all of NCDOT's noise activities now utilize GIS. NCDOT is officially not allowed to use Google or Bing mapping tools in its work, as it does not hold an enterprise license.

NCDOT does not yet have a comprehensive noise wall inventory of existing walls, but data on newly constructed walls are shared with FHWA. There are approximately 50 miles of walls and earthen berm sound barriers throughout the State.

GIS and Noise Modeling
To conduct its noise modeling, NCDOT's noise staff transforms GIS data into a format (usually a spreadsheet) compatible for uploading to TNM. GIS data helps streamline the TNM process since noise staff members may not have time to complete an on-the-ground survey of the project area. NCDOT generally conducts a preliminary noise assessment by viewing GIS features (such as roadway composition and topography) to identify the potential exposure of noise-sensitive land uses to traffic noise. Using TNM, NCDOT then performs a detailed design analysis for each project alignment by modeling every receptor. All receptors are linked to an address, owner name, and can be replicated for future analysis. In the past, cursory screening analyses of projects sometimes led to incorrect abatement modeling outputs. NCDOT now justifies detailed analysis even if construction does not proceed because the cost of doing so ($5-10,000) is much lower than building unnecessary noise walls ($1,000,000 - $2,000,000 per linear mile). Furthermore, such analysis can be used in the event a project alternative is revived or modified at a later date.

NCDOT maintains a rigid tolerance for noise modeling, which allows the agency to produce assessments at a very high level of detail. While +/- 3 decibels is the FHWA-recommended minimum and "industry standard," NCDOT applies a tolerance of +/- 1.7 decibels. NCDOT notes that assumptions built into Reference Energy Mean Emission Level (REMEL) data19 included in TNM are not as accurate as they perhaps could be, but TNM model(s) can be refined on a project-by-project basis to attain a leaner level of tolerance. NCDOT's goal is to utilize the TNM model in a way that shifts focus from noise sources to noise receivers. GIS advances this effort by enabling the inclusion of more detailed data related to a project's environmental context.

GIS has also enabled NCDOT to move forward on noise modeling and design noise walls without waiting for project survey data. For example, 11 noise walls were designed for a maintenance and widening project on Interstate 40 in Raleigh. Detailed analysis of surrounding neighborhoods indicated that 23,000 linear feet of previously unanticipated noise wall—at a cost of $12 million for 11 walls total—were necessary to respond to hundreds of impacts to the more than 1,500 residences in the vicinity of the project. GIS data from Wake County were used to model these neighborhoods in TNM, which involved validating 30-40 discrete monitoring locations (see Figures 5, 6, and 7). Even without survey or preliminary design data, NCDOT's noise consultant was able to design the noise walls.

Screenshot of Hand Modeling of I-40 in TNM Using GIS showing an aerial model of a section of I-40 with colored lines Figure 5. “Hand Modeling” of I-40 in TNM Using GIS.
Screenshot of Resulting Existing Condition TNM Model for I-40 Widening showing a color-coded line drawing view of the same section of I-40 as in Figure 5 Figure 6. Resulting Existing Condition TNM Model for I-40 Widening.
Screenshot of Resulting Noise Wall Design for I-40 Widening. Figure 7. Resulting Noise Wall Design for I-40 Widening.

Data
NCDOT uses the same baseline GIS data each time it runs TNM, including ground elevation or elevation contours, receptor locations, vegetation, land cover, drainage, and utilities. NCDOT also adds additional "acoustically relevant" data as available/appropriate, such as existing roadways, bodies of water, large infrastructure, and tree zones (tree zones are subjective and are only used to validate the noise model).

The most centralized GIS data source for NCDOT's noise assessments and modeling is a statewide repository called NC OneMap.20 The State of North Carolina began developing NC OneMap in 2003. It is a free, online, and publicly-accessible database containing data from numerous State and local agencies (see Figure 8). Information in the database includes wildlife, wetlands, land uses, and other topic areas. Currently, a minimal amount of county-level data available exists in this resource, but eventually NC OneMap is expected to become the single repository for local and statewide GIS data. NC OneMap data that is most useful for NCDOT's noise team includes information on elevation contours, topography, vegetation, hydrography, utilities, and building construction elevations.

Screenshot of the data browse function within NC OneMap's Geospatial Portal Figure 8. Screenshot of NC OneMap's Geospatial Portal (data browse function).

Benefits
One of NCDOT's primary lessons learned is to avoid using the term "spatial analysis" when referring to noise assessments, as these terms may imply that noise assessments are simply calculations of distance between sources and receivers. NCDOT believes that the physics of sound should be factored into the spatial relationship between sources and receivers, which NCDOT finds is made easier through the use of GIS.

Time and cost savings are two noted benefits of using GIS in NCDOT's noise analysis. While GIS sometimes requires more detailed front-end work, especially for noise modeling, NCDOT found that the total amount of work involved in noise analysis has decreased. If accurate data are added to TNM from the beginning, the need to make large reconfigurations of noise mitigation plans as a result of minor changes to a project have been minimized. Furthermore, due to limited staff resources, NCDOT does not believe it would be able to meet project deadlines without the help of GIS.

NCDOT has found that GIS data are often more detailed and more useful than survey data collected for a highway project. For instance, the ground line for the terminus of a noise wall was off by 1.5 feet on one project because survey data used 50' surface points. NCDOT notes that GIS data would have been more accurate in that circumstance.

NCDOT has been able to design noise walls and berms using only GIS data because the determining factor in designing a noise wall is an elevated line in the sky, called the "top of the wall" (or acoustic) profile. This is the line the top of the wall must take in order to mitigate noise as it travels from source to receiver. The noise wall can be designed using GIS before a survey is complete because as long as the top of the wall is accurate, the ground line can later be adjusted as needed. Since GIS data may not pick up on every dip or rise of the ground, using a top of the wall profile allows for greater design flexibility to prevent wall height from undulating across different elevations. For this reason, NCDOT no longer specifies wall heights.

The top of the wall profile is generally tied to the roadway vertical profile, though it may also be tied to the designed offset (such as the centerline) of the roadway. The wall's final horizontal alignment and ground profile (i.e., where the wall will meet the ground) is ultimately confirmed through a field survey. If the survey indicates a significant change in the roadway's designed offset or horizontal or vertical alignment, the top of wall profile may have to be adjusted, depending on its adjacency to the edge of pavement. If the top of wall profile is designed with a lesser correlation to the edge of pavement (such as by selecting a location at the top of a cut-section or near the right of way limits, for example), then only very significant changes in the roadway's horizontal and/or vertical alignment will necessitate a revision of the top of wall profile.

GIS also assists NCDOT in identifying details on receivers (such as building shape, height, presence of berms, etc.), which NCDOT believes is sometimes an undervalued aspect of noise analysis. This may be because roadway engineers are not typically trained to collect information beyond the highway right of way, where receivers are located. Based on project experience, NCDOT believes that appropriately detailed noise models result in more accurate traffic noise level and impact prediction, as well as more efficient and aesthetically pleasing abatement designs. Furthermore, detailed modeling outside the roadway also benefits any future road widening projects, since updating the noise model only requires a change in the modeling of proposed roadway design features.

Challenges
While there are numerous benefits associated with use of GIS, NCDOT reported that it can be difficult to rely on NC OneMap as its main source of GIS data. The map can be unstable and sometimes crashes. Some staff members have found the system's navigation to be cumbersome at times. Additionally, NC OneMap does not currently have many detailed county-level datasets that are important to NCDOT's noise analyses. Collecting data from individual local governments can be time-consuming, and this information sometimes contains inconsistencies due to lack of coordinated data collection at the local level. NCDOT notes that, for some counties, it is particularly difficult and costly to find quality elevation data.

GIS data from areas outside the highway right of way are included in TNM, though to use this information, assumptions must sometimes be made about the data's accuracy. Per FHWA regulations, noise impacts cannot be assessed using only noise contours created by GIS; only TNM and the algorithms it contains must be used.

It can be difficult to validate noise models for new roadways that have no existing noise sources since there are no "real world" data to confirm a model's predictions. Approximately, three-quarters of NCDOT's projects do have existing noise sources, so these challenges are not typical. When applicable, NCDOT will collect ambient noise level data at appropriate locations, making iterative adjustments to TNM to ensure that the model's predicted noise levels are within acceptable tolerances of those monitored in the field.

Future Steps
NCDOT's noise team is currently building a statewide library of all TNM models and is considering developing a GIS repository for all noise analysis data, results, design, and recommendations for use in future projects or to respond to public requests and concerns. Used in this way, NCDOT considers GIS a "forward-working" tool rather than simply a storage system. NCDOT also sees potential in using such a system to link the date, manufacturer, and condition of noise walls with environmental data so as to more proactively track and predict maintenance needs for the future.

NCDOT believes that developing an agency-wide GIS-based tool might enhance the noise screening process if criteria such as elevation, forestation/vegetation, structures, water features, roadways, and buildings were included, as well as existing noise abatement measures. This type of tool could also contain a digitized catalogue of noise abatement measures. However, NCDOT currently does not have staff capacity in terms of skills or availability to build such a tool. NCDOT might consider building this type of tool in the future once its consultants are fully trained on NCDOT's and FHWA's new noise abatement policies and procedures. NCDOT also plans to hire consultants to continue to educate the noise team on GIS techniques, since NCDOT's other GIS staff are already working at capacity.

Finally, NCDOT would ideally like to compile a digitized noise wall inventory to add to NC OneMap and make it available to local governments.

3.5 Ohio Department of Transportation (ODOT)

Background
ODOT's noise section is in the Office of Environmental Services within the Planning Division.21 One staff member in the central office is responsible for a majority of ODOT's noise analysis.

ODOT uses GIS and geospatial data to:

ODOT, which has about 181 miles of noise walls across the State, uses GIS to locate and catalog noise barrier walls. Geospatial data from Google Earth and Bing Maps are also used to support traffic noise modeling analysis.

ODOT identified a need to capture information about noise barriers across the State in a spreadsheet (see Figure 9). Originally in Quattro, the spreadsheet was converted to Excel in 2004-2005 when the State switched from a Corel Office Suite to Microsoft Office. The spreadsheet was later enhanced to help staff better and more consistently address questions from ODOT District Offices, the public, and others about the noise barriers and their placement.

In developing the spreadsheet, ODOT considered what type of information would be needed to satisfy public information requests. When available, project plans were used to capture a range of information about the barriers, including their location, when they were constructed, their square footage, materials used in construction, length, and total costs (based on an average of $25/square foot).

Screenshot of Select Fields from ODOT's Noise Barrier Spreadsheet Figure 9. Screenshot of Select Fields from ODOT's Noise Barrier Spreadsheet.

Developing and updating the spreadsheet was a three-phased effort. The first phase involved working with a consultant to conduct a limited inventory of a few central Ohio counties to develop a proof of concept, followed by a second phase focused on collecting a statewide inventory. In 2007, ODOT hired the same consultant to add newly-constructed barriers to the inventory and update the viewer application. Additional data were added including panel dimensions, wall elevation and height, and GPS coordinates. The consultant also collected information on any points of damage to better assess the condition of the barriers. Additionally, the consultant took pictures of damaged areas along the walls as well as general pictures of the front and back of each wall. Collecting these data took six to eight months. Information on wall contractors and material manufacturers were also compiled by communicating with district offices and suppliers.

There were some challenges in this effort. For instance, data was delivered in shapefile format, though at the time ODOT used GeoMedia (ODOT is the only State agency in Ohio that does not use ArcGIS.)

After the field data collection effort was completed, the consultant created a user-friendly ESRI-based desktop viewer to store data from the spreadsheet. ODOT aimed to provide each of its districts with access to the desktop application as a way to promote data-sharing across districts. However, over the course of developing the viewer, ODOT's IT department updated its operations structure. New IT policy prevented the desktop viewer from accessing multiple servers, and challenges were encountered in sharing data across firewalls and obtaining administrator rights to install the viewer. Additionally, some districts used different geospatial software, making it difficult for users to consistently access or update data. To date, these challenges have not been resolved. As a result, ODOT has moved away from developing the ESRI viewer and focused more on using the spreadsheet as a way to store noise wall information.

When the reporting requirements of 23 CFR 772 were established, ODOT staff determined that it could use the spreadsheet to respond more easily to these requirements. Staff decided to georeference a portion of information in the spreadsheet (e.g., geographic coordinates of Type I and II noise walls built since 2005) using GeoMedia. This process took approximately three months.

ODOT has georeferenced all of the information from the noise barrier spreadsheet into GeoMedia. Staff members concurrently use the spreadsheet and GeoMedia to respond to 23 CFR 772 reporting requirements.

The GeoMedia tool has evolved over time. Initially, it functioned like the spreadsheet as a basic repository of information, helping ODOT address questions such as the age of the noise barriers, their total cost and square footage, what material they are comprised of, when they need to be replaced, and the length or number of noise barriers within a particular ODOT district. While the tool continues to be an information storehouse, it has also become a management tool that provides a better way for ODOT to manage maintenance or replacement schedules as well as other needs for the noise barriers. Data in the GeoMedia tool and spreadsheet are updated on an as-needed basis.

Most recently, ODOT staff has digitized information on any replacement walls constructed since 2005, which helps staff members know the lifespan of a noise wall. The tool now contains information on all noise walls constructed since 2005 (information was gathered from project plans and field surveys).

Total cost to conduct the pilot data collection for the spreadsheet, complete the full statewide data collection, develop the GeoMedia viewer application, and update the noise wall inventory was approximately $160-170,000.

Geospatial Data for TNM Analysis
ODOT is also using geospatial information from Bing Maps and Google Earth to support traffic noise modeling analysis. Within the past year, staff have focused on gathering information from Google Earth using software called Maptool, available from Zonum Solutions22 (see Figure 10). Maptool is essentially a pre-programmed tool that manipulates Google Earth to find data on elevations, distances, and areas. It also allows ODOT staff to easily collect data on receptors such as homes, churches, schools, and parks.

Screenshot of Maptool showing an aerial photograph of a section of an eight-lane highway Figure 10. Screenshot of Maptool.

Maptool is used to gather all geospatial points from Google Earth to input into TNM to predict future noise levels for specific proposed projects. Using TNM, staff then assess potential noise barriers for transportation project sites and report on whether constructing a noise barrier is reasonable and feasible.

ODOT also uses data from web-based tools to support its noise analysis activities. ODOT uses Google Earth data to depict the locations and shape of potential barrier designs for proposed road projects. The department also uses data from Bing Maps to support noise barrier analysis. These data are supplemented by ODOT's statewide LiDAR data.

Benefits
ODOT has found benefits in using Google Earth data to support traffic noise modeling analysis. For example, roadway design files23 are a source for data to input into TNM, but these files typically do not include receiver (e.g., homes, schools, hospitals) or noise wall locations. In the past, when using roadway design files for input to TNM, ODOT staff members often had to estimate receiver and noise wall locations, which led to some data inconsistencies. Georeferencing receiver locations found in LiDAR data also turned out to be too cumbersome and time-consuming. Google Earth contains georeferenced information about both roadways and receiver locations; as a result, staff can now look to one information source, saving time and supporting data accuracy. One of the most significant benefits of using Google Earth is that its LiDAR data for Ohio comes directly from ODOT, as the agency recently (in the last year or two) donated its data to Google Earth. As a result, staff have the reassurance of knowing that Google Earth LiDAR data for Ohio are as accurate as possible.

ODOT has not developed any formal performance measures to evaluate or assess the GeoMedia tool or use of Google Earth to support traffic noise modeling analysis. On the basis of anecdotal information, the agency believes that the inventory and Google Earth data "meets or exceeds" its needs. In particular, staff noted that use of Google Earth data has streamlined noise analysis and has led to significant time-savings. Additionally, the GeoMedia tool has helped ODOT obtain information more quickly and easily. It has provided both cost and time-savings in responding to questions from district offices and the public about the noise walls.

Challenges
While using Google Earth data was advantageous, there were some difficulties. For example, elevation data from Google Earth was not always accurate. In some cases, when obtaining elevation information for a noise wall located on an overpass, Google Earth would frequently pinpoint coordinates for the road under the overpass without "recognizing" the existence of the bridge. In these cases, ODOT staff needed to develop workarounds.

ODOT also recognizes that not all of the information in its noise barrier inventory spreadsheet is accurate, as some data pulled from project plans have not been field verified. Staff members are continually conducting "detective work" to make the information as accurate as possible.

Furthermore, staff recognized that ODOT leadership currently considers GIS as a support tool, which increases the standards in terms of making the case for further investment in GIS tool development.

Future Steps
In the future, ODOT would like to measure the individual panels that form noise walls and add this information to both the spreadsheet and GeoMedia tool. This information would help ODOT staff members better understand when the panels need to be replaced. Panel information would need to be collected in the field, as data on panel dimensions are not captured in project plans.

The agency might also move forward to digitize all of the information contained in the noise barrier spreadsheet, including data from walls built before 2005, to provide a comprehensive picture of all noise walls in the State. However, this is not currently considered to be a critical need for the agency.

Lessons Learned
ODOT noted the following lessons learned:

3.6 Tennessee Department of Transportation (TDOT)

Background
TDOT's Air and Noise Analysis Section is composed of one primary staff person. The section is part of TDOT's Environmental Division.24

TDOT uses GIS for noise analysis to:

In the future, TDOT may use GIS for noise analysis to:

Between 2003 and 2005, TDOT began a Type II program to facilitate the construction of "retrofit" noise walls in older neighborhoods impacted by traffic noise from existing highways. As a first step toward starting this program, TDOT's Commissioner authorized a comprehensive Type II study to identify potential locations of Type II noise barriers along the State highway system. In response, TDOT developed an informal, internal GIS database cataloging information on existing noise walls (Type I walls) as well as potential locations of retrofit barriers across the State.

Currently, the primary users of the database are TDOT's environmental division staff as well as other TDOT personnel that oversee materials and maintenance. TDOT is exploring whether the database could be used to help communicate to the public about noise walls, but an approach has not yet been determined.

GIS Noise Wall Database
TDOT's GIS noise wall database uses an ArcGIS platform and contains an array of information on the State's existing Type I noise barriers as well as potential Type II noise barrier locations.

Type I noise barrier information in the database includes location, construction year, and construction materials. Type II information includes the locations of residential communities along the interstate highway system, estimates of existing sound levels, metadata, and locations that do and do not qualify for Type II barriers, as well as the reasons for ineligibility.

The database has been updated several times since the first version was completed in 2005. However, there are some Type I attribute data fields, such as length, height, and construction cost, which have not been populated due to lack of staff time. However, TDOT plans to complete the database in the future.

The initial purpose of the database was to respond to the TDOT Commissioner's request to identify locations for retrofit barriers. The database was used as an initial screening tool for potential Type II-eligible areas. It allowed TDOT to identify potentially qualifying neighborhoods within buffers adjacent to interstates. Each potentially qualifying area was evaluated and TNM modeling and barrier analyses completed to identify "benefitted residences" in each area. Where available, TDOT also used county property assessor data to determine the construction dates of residences in potential Type II areas. Ultimately, TDOT determined that 22 neighborhoods were eligible for Type II noise walls at a total cost of about $30 or $40 million. To date, three Type II noise walls have been constructed.

The database provides a formal way to organize information about noise walls that was not previously documented. For example, Federal funding cannot be used to construct a Type II noise wall for an neighborhood if a barrier was previously determined not to be feasible or reasonable as part of a Type I noise study. TDOT needed a way to quickly identify if a neighborhood had been studied previously for a Type I wall and then deemed ineligible. As a result, all Type I projects on the interstate highway were included as objects in the GIS database, which allowed staff to quickly identify if adjacent neighborhoods were ineligible for Type II walls. TDOT's access to statewide parcel data also facilitated this process.

In the future, staff members hope to use the database to better manage the Type I noise wall inventory and to answer questions about walls' cost, number, and location. TDOT also plans to make some modifications to the GIS database to allow development of queries and reports that would generate specific data required by the Federal noise regulations in 23 CFR 772.

The database continues to evolve. TDOT is currently adding information on noise-related complaints to an Access database. The agency would like to geocode the complaint location, contact information, date, and TDOT's response and add this information to the GIS database to build a comprehensive library of all noise complaints. Beyond helping staff better visualize spatial patterns among complaints, geocoded complaints would allow staff to more easily access detailed information, allowing for quicker and more thorough responses. TDOT is still determining how to proceed with geocoding complaints and identifying potential users of the complaint inventory. There is currently no definite timetable for when this effort will occur.

GIS for Noise Studies, TNM, and Noise Modeling
TDOT is not currently using GIS on a regular basis to conduct noise assessments, although TDOT has used GIS for several individual noise applications.

In one example, TDOT identified potential Type I noise barrier locations for several alternatives using GIS data developed for a major study on the feasibility of building a third bridge across the Mississippi River in Memphis. GIS data on land uses were used to help assess each alternative's potential to create noise impacts. Aerial photography was used for locations where GIS data was not available. TDOT then worked with a consultant to summarize the noise impact and noise barrier information in a report.

TDOT also uses some GIS data with TNM on a project-by-project basis. TDOT developed a manual that outlines the process for using TNM to conduct noise modeling. The manual suggests using GIS "when possible" to support modeling but does not specify when or how to use GIS.

Geospatial data from TNMap Portal, a web-based, statewide GIS system developed by the Tennessee State Office of Information Resources25 is used to support noise modeling (see Figure 11). TDOT noise staff also use geospatial data from Google and Bing Maps extensively to augment modeling efforts. In particular, the Google Street View and Bing "bird's eye" view features can be used to help identify the unique topography of a particular area and to address queries and complaints about noise walls. While this feature is not available for all roads (either in Google or Bing maps), it can be helpful as staff do not have to conduct a site visit to obtain information.

Screenshot of TNMap showing a map of Tennessee with its counties outlined and four major cities labeled: Nashville, Memphis, Chattanooga, and Knoxville Figure 11. Screenshot of TNMap.

There are no significant costs associated with TDOT's use of GIS to support noise analysis or its development of the GIS database. Some municipalities might charge TDOT for data, though they will typically provide data for free if TDOT documents that the data will be used for project analysis on behalf of the State. In the future, reciprocal agreements might be formalized between local government agencies and TDOT to cover data-sharing.

Benefits
Making GIS information available "at its fingertips" has been very beneficial to TDOT. Documenting past highway program activities in the GIS database has helped inform new policy directions. GIS data have given TDOT a much better understanding of noise impacts and mitigation measures for current and past transportation projects.

Additionally, the quality of county-level GIS data has improved as technology has evolved, making it progressively easier for TDOT to use GIS data to support noise modeling. Higher quality data in noise modeling improves accuracy and decision-making.

Challenges
TDOT has sometimes had difficulty recruiting and retaining staff members with the expertise and training to make best use of GIS capabilities.

Obtaining high-quality GIS data and detailed local-level information for areas beyond the highway right of way has also been a challenge for TDOT, since survey crews generally focus on collecting information only within the right of way. Most roadway design files26 show only a small area beyond the highway right of way, even though TDOT often needs to look at much larger areas to accurately assess noise impacts.

Furthermore, GIS data is not always available for more rural areas of the State. In some cases, TDOT staff members will use aerial data, property assessors' maps, local-level information, TDOT's project design files, or information from the U.S. Geological Survey to develop more accurate data of a larger area. However, this can lead to challenges with resolution. Currently, TDOT is using a wide variety of geospatial data sources since it does not have a centralized source that provides all the needed information. Searching for data can add time and cost to noise assessments.

Using GIS in conjunction with TNM also presents challenges as TNM does not currently utilize a GIS interface and is somewhat limited in the extent to which external data can be used. As a result, TDOT personnel must identify "workarounds" that involve translating data into appropriate file formats to use with TNM. Furthermore, TDOT's GIS database is on a statewide scale while TNM outputs are on a project scale, leading to challenges and potential discrepancies.

Future Steps
Ultimately, TDOT envisions adding the GIS database to its external website. This would support TDOT's communication with the public by allowing individuals to access noise wall-related information for specific areas. It would also enable TDOT to respond more efficiently to questions from the public about noise walls and the reasons why neighborhoods either did or did not receive one.

TDOT has already started developing an enterprise GIS-based environmental management system and noise staff would like to see that work continue. Several years ago, TDOT noise staff met with an internal web developer to provide a list of data fields relevant to noise that would be useful to include in this system. The system is envisioned as a centralized clearinghouse of information that would assist noise staff in meeting NEPA requirements (there is no definite delivery date for when the system would be completed; it is an ongoing effort). Using data from this system, for example, noise staff could develop a detailed map of an area during a project's planning phases as a way to assess potential noise impacts. In the meantime, noise staff have looked to a variety of sources, including resource agencies such as the U.S. Fish and Wildlife Service, to conduct this type of screening.

To be most useful to support noise analyses, the system would need to capture elevation and contour data as well as information on land use type and category as defined in 23 CFR 772. The benefit of the application would be in compiling information from a variety of sources into a "one-stop shop."

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Lessons Learned
TDOT noted a few lessons learned from its experiences:

3.7 Virginia Department of Transportation (VDOT)

Background
VDOT's Integrator 2.0 enterprise GIS is an internal, web-only application that has been in use since 1998. Integrator contains approximately 250 layers that are maintained and used by various VDOT business units to support a spectrum of business functions (however, VDOT does not maintain most environmental data in this web application). These layers include a variety of noise-related information, including digital elevation model (DEM) data layers and a sound wall location data layer.

VDOT uses GIS for noise analysis to:

Three VDOT staff members are augmented by two on-call consultants who focus only on noise issues.27 There are about 130 miles of Type I noise walls across the State; VDOT does not have a Type II noise program.

Within the last several months, VDOT's noise staff members initiated an effort to update Integrator's sound barrier data layers using data obtained over the past five years from Fugro Roadware, an infrastructure data collection company. The update will help VDOT respond to the reporting requirements of 23 CFR 772 and will support VDOT in more accurately documenting the locations of sound walls.

The update is expected to be completed within the next one to two years. VDOT's maintenance division is in the process of writing a manual to guide the inventory update and associated data "ground-truthing." There are no specific costs associated with this update other than staff time.

By updating Integrator's sound barrier layers, VDOT aims to help staff better assess the conditions of noise walls, which will then in turn help determine appropriate steps for noise wall maintenance.

Uses of GIS
Integrator's current sound wall layers show the locations of noise walls across Virginia (see Figure 12). This layer was created using 2002 aerial imagery. The imagery did not have a fine degree of resolution and when the information was digitized, data on retaining walls and fences were erroneously included in the layer along with the actual noise walls. As a result, the layer indicated that VDOT had over 450 more miles of noise walls than it actually does. That layer has since been edited to remove many of the erroneous barriers and now totals 123 miles of sound walls; this will soon be replaced by the new layer created from VDOT's current data collection efforts.

As part of this effort, VDOT is currently working with Fugro Roadware to collect a variety of digital pavement data and imagery as well as pavement information on all of the State's primary roadways, ramps, and loops.28 Fugro Roadware will also collect various data points on noise walls, including information on the walls' start and end points, construction materials, and conditions. Subcontractors will also conduct visual inspections of each mile of imagery. Ultimately, VDOT will digitize this information and update the existing Integrator GIS noise wall layer.

Screenshot of Integrator's Noise Wall Layer showing an aerial photograph of a highway section which has some edges colored orange to signify sound barrier locations Figure 12. Integrator's Noise Wall Layer.29

This update will help VDOT resolve earlier information discrepancies and meet 23 CFR 772's reporting requirements. VDOT will also use the new layer to model maintenance needs. For instance, maintenance staff could view catalogued images to assess the extent of damage on the walls and identify appropriate mitigation steps. Updating this layer with maintenance deficiencies will support more accurate budgeting for maintenance purposes. However, VDOT is still determining the best approach for adding information on planned walls into GIS.

VDOT uses GIS to support other noise activities in addition to capturing sound wall locations and conditions. For example, VDOT supplements civil surveys with terrain models or coverages from the Integrator DEM layer—particularly at the county level—to understand what land features exist beyond surveyed highway right of way limits. By supplementing land use information and other terrain coverages beyond the right of way, the noise model can reliably predict more accurate sound level results. VDOT noted, however, that while having civil terrain data available at a very fine and detailed level helps improve modeling accuracy, this information is not always available. A majority of the GIS terrain data30 used to supplement the noise studies are publicly available through the Virginia Geographic Information Network (VGIN), which is run by the Virginia Information Technologies Agency (VITA), a State agency that provides IT services to other State agencies and the public.31

It is also considering implementing GIS to log noise-related complaints received from the public and to identify when and where past complaints have occurred. VDOT would like to be able to use this information to identify and document areas with a history of noise complaints, but has found this difficult given broader privacy concerns about linking personal identification information with the complaint. Due to these privacy concerns, it is unknown whether an internal desktop GIS tool or an enterprise GIS (available either internally or externally via a website) would be the best method for dealing with these issues.

Additionally, VDOT uses desktop GIS to develop graphics for noise reports and in conjunction with TNM. To do so, sound wall design plans are imported and georeferenced into a desktop GIS where they are converted into useable TNM input files. Steps are needed to convert VDOT's project coordinate system into a recognized projected coordinate system in GIS. After they are input and processed into TNM, the calculated (predicted) results are exported back into the desktop GIS where they can be analyzed more quickly and efficiently than in TNM. Using GIS, the locations of potential noise barriers are then exported out of TNM and imported into GIS where the barrier essentially undergoes a "reality check" of whether a noise barrier will be effective if it is placed at that location. The potential barriers are also evaluated to ensure that the proposed wall heights will effectively abate noise and that the wall will adequately break the line of sight with the roadway and impacted receptors (i.e., so that the roadway cannot be seen from an impacted receptor). The TNM is then used to ascertain final heights and lengths for proposed noise barriers. VDOT noted that workarounds are needed to use GIS data with TNM since the model's interface does not currently utilize a GIS platform.

GIS Data
VDOT obtains GIS data from many sources, including VGIN. Through VGIN, VDOT can access several GIS layers, including information on terrain lines, aerial imagery, orthoimagery, and digital road centerlines, which are used in conjunction with VDOT's Integrator noise layers.

VDOT's noise staff members also contact local planning divisions on an as-needed basis to ask for digital or PDF versions of development plans. Information from these plans is then georeferenced into the desktop GIS for noise modeling purposes. When necessary, VDOT can also create its own files from development plans to accurately depict any development that has occurred since a project plan was created.32

VDOT also extracts noise-related GIS data from other databases, such as Radford University's spatial data server33 or from Google Earth to validate and ground-truth information.

Benefits
VDOT noted that use of GIS data has made noise modeling and noise mitigation more efficient. For example, GIS has made it easier for VDOT to compile information on receptor locations, noise levels, and other factors and input this information as a package into TNM.

Additionally, use of desktop GIS increases the level of accuracy of noise analyses. It also allows for greater flexibility and efficiency in barrier design by ensuring that the barriers have adequate termini and provide proper noise attenuation.

While there are many anecdotal indications of the benefits of GIS, it has been difficult for VDOT to comprehensively assess either the benefits or challenges related to VDOT's use of GIS, as the agency is still in the early stages of updating the GIS noise barrier layer. Nevertheless, VDOT's noise section is actively progressing with its use of GIS to assist with noise analyses.

Challenges
VDOT is addressing difficulties related to declining resources and funding, especially in regards to investments that support noise wall maintenance, collecting GIS data, or expanding GIS tools. The computing capacity required to run GIS makes it particularly important to continually invest in technology infrastructure and upgrades, but the need for continual software and data updates can make it more difficult to obtain funding. There is an added challenge of using freeware and third party non-ESRI GIS add-ons. A portion of VDOT's GIS users prefer using Google Earth to make business decisions with Integrator. However, VDOT IT policy prohibits downloading of "unapproved" software and can act as a roadblock when trying to obtain necessary tools needed for production.

Another challenge VDOT has faced is identifying how to best upload noise wall information to GIS format given the fact that a constructed wall might have some variances (in terms of specific dimensions, location, etc.) in how it is represented in a project plan. The agency is currently identifying approaches for more consistently collecting information on constructed walls and adding that information to the GIS noise layer.

Future Steps
In the future, VDOT would like to conduct more on-the-ground surveys to verify the information that the consultant is collecting on noise walls across the State and help districts and residents better identify noise concerns. Conducting this survey of noise walls might cost $250,000.

VDOT is also exploring the collection and use of LiDAR to determine the locations and top of wall elevations for constructed noise barriers across the State. Costs for this effort are not available at this time.

3.8 Washington Department of Transportation (WSDOT)

WSDOT uses GIS for noise analysis to:

Background
WSDOT's noise program is organizationally located within the agency's Environmental Services Office. There are five staff members working within the Air Quality, Noise, and Energy program.34 Two other WSDOT staff manage the Environmental Service Office's GIS data, including its noise layers. The agency used GIS to develop a noise wall layer that displays a variety of information about the 20 miles of noise barriers in the State, including existing locations, and eligible locations for Type II retrofits.

The initial source of data for this layer was a spreadsheet-based noise wall inventory that WSDOT developed to meet Federal requirements under 23 CFR 772.

In addition to using GIS to capture information on noise walls, WSDOT uses GIS data on an ad hoc basis for a variety of other noise analyses, such as identifying where noise might cause impacts near a roadway project and to develop maps and graphics to support these analyses.

GIS Noise Tools
WSDOT's first statewide noise wall inventory was developed in May 1981. Initially, it was a book of photographs, graphics, and text describing constructed barriers across the State. Information on Type II barriers was added to this document in 1999 when WSDOT began its Type II program. In 2005, WSDOT took information available in the document and developed a new spreadsheet-based noise wall inventory to respond to the reporting requirements of 23 CFR 772 (see Figure 13). This was developed over the course of several months using data culled from the previous inventory, project plans, as well as field visits to confirm data. There were no specific costs associated with development of this inventory besides staff time.

Screenshot of Select Fields for existing walls from WSDOT's Noise Inventory showing a data table Figure 13. Screenshot of Select Fields from WSDOT's Noise Inventory (for existing walls).

As a next step, WSDOT selected attributes for two datasets—proposed and existing walls—and uploaded them into the Workbench (see Figure 14), The Workbench is a GIS application customized by WSDOT that contains over 700 layers of environmental and natural resource management data, including the noise-related information. The GIS Workbench is accessible only to internal WSDOT staff, although some data are made freely available to the public through the GeoData Distribution Catalog.

Attributes added to the Workbench included the materials used for wall construction, the year the wall was built, its total cost, length, height, city or county location, source of the data, material used for construction, method of construction (e.g., precast), barrier type (Type I or Type II) and potential locations for proposed Type II noise barriers. These attributes were chosen to add to the Workbench because of the frequency with which project developers and engineers require this information. Information from WSDOT's linear referencing system35 was also added to show where noise walls are located in relation to the State's roadways.

Screenshot of Existing and Proposed Noise Walls from the Workbench showing an aerial photograph with color-coded lines to specify existing and proposed walls Figure 14. Screenshot of Existing and Proposed Noise Walls from the Workbench.

These data are updated on an as-needed basis. For example, following construction of a project that includes noise walls, WSDOT's noise staff work with project teams to obtain information about the cost, height, length, and final location (based on roadway mileposts) of noise walls that are updated into the GIS.

In the noise context, WSDOT uses the GIS Workbench primarily for project scoping and planning to identify appropriate noise abatement strategies and address noise-related queries from the public, such as whether a specific community is eligible for a Type II retrofit barrier. Workbench noise data also help support other divisions' functions. For example, WSDOT's biology office might use the data to identify the effects of noise walls on wetlands, or the hydrology office might use the data to understand how noise walls impact drainage patterns. The noise wall GIS data are also posted on a public website, WSDOT's online GeoData Distribution Catalog, to support the broader goal of sharing information both within and outside of WSDOT.36

TransMapper, short for "Transportation Mapper," contains a subset of information found in the Workbench.37 TransMapper is an internal tool developed using cost-free ArcGIS Explorer and web data services. The tool contains priority data layers and base maps stored within the GIS Workbench to support numerous agency business functions (see Figure 15).

TransMapper screenshot showing noise wall locations, both existing and proposed Figure 15. Screenshot of TransMapper with Noise Wall Layers (subset of noise barrier layers shown in Figure 12). Green Indicates Proposed Walls and Red Indicates Built Walls.

WSDOT uses TransMapper in a variety of noise analysis activities. Staff members use the application to identify potentially sensitive receptors within project alternatives, eliminating or reducing the need to visit every site. To accomplish this, alignment lines from project alternatives, obtained as a shapefile from WSDOT's planning department, are imported into TransMapper. Using "worst-case" traffic data, staff use TNM to identify specific distances from roadway alternatives that achieve a 10-decibel level increase or produce modeled sound levels at or above 65.5 decibels (see Figure 16). Using TransMapper, staff members can then create an "area of influence" buffer around each project alternative. If potentially sensitive receptors are located within this buffer, they will be modeled in TNM to determine reasonable and feasible noise abatement.

TransMapper screenshot of the Noise Analysis layer with color-coded lines Figure 16. Screenshot of Noise Analysis in TransMapper. (Red Lines Represent Existing Roadways. Yellow Lines Represent Buffers Associated with Different Project Alternatives. Yellow and Green Dots Represent Sensitive Receptors such as Residences).

WSDOT does not use GIS data with TNM. However, the agency does use GIS data, maps, orthoimagery, and aerial imagery to refine the scope of TNM modeling by identifying residences located next to roadways that might be impacted by traffic noise. These data are primarily obtained from the Workbench or TransMapper applications.

Potential Area of Noise Effects GIS Model
Currently, project managers and engineers do not have good tools to assess a project's early phases and whether a noise wall will be necessary. To address the need for early scoping tools, WSDOT is developing a "Potential Area of Noise Effects" GIS model using Workbench data such as annual average daily traffic, posted speed limits, volume, and vehicle class. This model will calculate the distance to the 65.5 decibel level limit38 using emission equations provided in 23 CFR 772. The calculation result will be fed back to GIS to generate a single GIS data layer with buffers that vary in distance from the roadway according to the likelihood that noise mitigation will be necessary (Figure 17). Essentially, the model will help flag areas that are likely to need abatement structures to allow for better estimates of wall design and construction costs. The model results are currently only intended to provide a rough estimate of those needs. The model will also provide a mechanism to share and communicate information to the public.

Jurisdictions could also use information from the model to plan and zone in ways that avoid placing more land uses within or near these thresholds. In order to increase the accuracy of this tool, WSDOT intends to add land-use information to the Workbench, so that it can be incorporated into the model in the future. The model might also incorporate information on sound levels generated from TNM as well as geospatial coordinates for each noise receiver.

Screenshot of Output from WSDOT's 'Potential Area of Noise Effects' GIS model which shows a section of Rte 539 colored in red and a section colored in yellow Figure 17. Screenshot of Output from WSDOT's "Potential Area of Noise Effects" GIS model. Different Line Widths Indicate Different Traffic Speeds and Volumes.

Benefits
WSDOT has not developed any formal metrics to assess its use of GIS. However, statistics are maintained on how many staff access specific GIS layers from the Workbench. In the future, WSDOT intends to use these statistics to evaluate which divisions or groups within WSDOT are using GIS noise layers. This could help show the extent to which staff throughout the agency rely on GIS to accomplish business tasks and help noise staff tailor the screening-level tool to best meet user needs.

In making information broadly available throughout WSDOT, the Workbench and TransMapper applications have helped staff more effectively communicate with each other and with the public. For example, prior to adding noise layers to the Workbench, WSDOT's project scoping staff would have needed to approach noise staff to ask whether a noise barrier existed in a particular location. Noise staff would have manually scanned project plans and maps to respond. Now, scoping staff can access these data on demand. The potential need for Type II barriers can be considered at the beginning of a project rather than at its conclusion. Additionally, the accessibility of the Workbench and TransMapper applications assists staff members with responding to public queries about noise and allows a better prediction of the need for noise variances for construction. Cataloging noise barriers in GIS also helped WSDOT create a lasting library of information about the agency's noise abatement activities, mitigating the effects of staff turnover or transition.

Furthermore, GIS has streamlined agency processes. For example, the Workbench makes it easy for staff to collect information on noise walls without having to drive to specific locations.

Future Steps
The agency is still evolving in its use of GIS to support noise analysis. Staff members intend to think more about how TransMapper and the GIS Workbench could be used to anticipate potential needs for noise analysis as well as communicating with the public and other parts of the agency. Additionally, WSDOT staff members would like to work on improving data accuracy/consistency and integrating noise wall decision documentation with GIS to improve access to decision records. Overall, WSDOT noted that GIS has provided many benefits and that "the more we learn about GIS, the more we ask ourselves how we can expand its use."

WSDOT intends to continue refining the GIS noise data layers available in Workbench and TransMapper, particularly in terms of making these data more accurate. In the next six months to one year, WSDOT anticipates developing an internal website to assist staff with cataloging and accessing records on past noise studies to help answer questions about why a previous noise decision was made. These report locations would also be available in GIS so that while scoping a proposed project, a user could open the report(s) for nearby previous studies. WSDOT will also be considering other ways to improve complaint response processing thorough better use of available information management technologies, including GIS.

Lessons Learned
WSDOT suggested the following lessons learned:

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FOOTNOTES

1 FHWA. Highway Traffic Noise in the United States: Problem and Response. 2006. https://www.fhwa.dot.gov/environment/noise/regulations_and_guidance/usprbrsp.pdf
2 Additional information on FHWA's efforts to promote transportation agencies' applications of GIS, geospatial tools, and data can be found on the FHWA GIS in Transportation website: https://gis.fhwa.dot.gov.
3 For the complete text of 23 CFR 772, see https://www.ecfr.gov/current/title-23/chapter-I/subchapter-H/part-772?toc=1.
4 "Noise wall" is used here interchangeably with "sound wall" or "noise barrier." Participants in this research effort regularly used all of these terms.
5 Additional information about TNM is available at https://www.fhwa.dot.gov/environment/noise/index.cfm.
6 For many examples of how GIS has been used to support an array of transportation goals and objectives, see the FHWA GIS in Transportation website.
7 For some examples of this research, see "Simple Tools for Traffic and Transit Noise Studies." 2002), available at https://ascelibrary.org/doi/10.1061/%28ASCE%291076-0342%282009%2915%3A2%2888%29. See also "GIS-Based Model for Noise Analysis" (2009), available at https://trid.trb.org/view/890902.
8 "Simple Tools for Traffic and Transit Noise Studies" (2002) is available at https://proceedings.esri.com/library/userconf/index.html.
9 North Carolina's "NC One Map," a statewide repository for local-level natural resource data, served as an exception, as NCDOT noted that access to local-level data through this tool is continually being expanded.
10 Additional information on MD iMap is available at https://imap.maryland.gov/.
11 Available at https://www.sdsfieonline.org/Home/Index.
12 For more information on FlexViewer, see https://resources.arcgis.com/en/help/flex-viewer/concepts/.
13 More information is available at https://doc.arcgis.com/en/.
14 More information on ETDM and the EST is available at https://etdmpub.fla-etat.org/est/.
15 ProjectWise is engineering project management software program that facilitates the sharing and review of project engineering information in a single platform.
16 iMap is available at https://imap.maryland.gov/. iMap is a Flex Application with external systems such as ArcGIS Server 10 and eGIS Web Application. The eGIS system allows various MDSHA departments to add content via the GIS Web Application, build tools and widgets, or build stand-alone applications that they can embed in websites or launch from websites.
17 “NCDOT Traffic Noise Abatement Policy” is available at https://connect.ncdot.gov/resources/Environmental/PDEA%20Procedures%20Manual%20Documents/2016%20NCDOT%20Traffic%20Noise%20Policy.pdf. The accompanying Traffic Noise Analysis and Abatement Manual is available at https://connect.ncdot.gov/resources/Environmental/PDEA%20Procedures%20Manual%20Documents/2016%20NCDOT%20Traffic%20Noise%20Manual.pdf.
18 For a definition of NAC, see https://www.fhwa.dot.gov/environment/noise/regulations_and_guidance/faq_nois.cfm.
19 REMEL data are included in noise prediction models such as TNM. REMELs represent the "maximum, energy-averaged, A-weighted sound level of a vehicle type." (Wayson, Ogle, and Lindeman, 1994: http://www.adc40.org/docs/paper_award/1994%20Paper%20Award.pdf).
20 NC OneMap is available at https://www.nconemap.gov/.
21 The noise section's website is available at https://www.transportation.ohio.gov/programs/noise/noise#page=1.
22 Zonum Solutions contains a variety of free software tools. More information is available at www.zonums.com.
23 Design files are electronic packages of information about a constructed roadway.
24 TDOT's policy on highway traffic noise abatement is available at https://www.tn.gov/content/dam/tn/tdot/documents/Signed_and_Approved_TDOT_Policy_on_Highway_Traffic_Noise_Abatement_July_13_2011.pdf.
25 TNMap Portal is available at https://tnmap.tn.gov/.
26 Design files are "packets" of geospatial information coded in particular ways. These files can be shared and uploaded into a GIS.
27 The VDOT noise program's website is available at https://www.virginiadot.org/projects/pr-noise-walls-about.asp.
28 VDOT's contract with Fugro Roadware, which has multi-year renewable potential, includes collecting images and data on more than 12,000 directional miles of interstate and primary highways and approximately 7,700 miles of asphalt secondary roads. Over the course of the contract, Fugro Roadware will collect a variety of data for the State including faulting, rutting, roughness, forward perspective right of way and pavement digital imagery. See also https://www.fugro.com/media-centre/news/fulldetails/2010/03/31/fugro-awarded-new-contract-for-state-pavement-programme-virginia-us.
29 This screenshot shows noise barriers along Interstate 95 near the Virginia 123/Gordon Boulevard intersection near Woodbridge, Virginia.
30 Virginia Base Mapping Program's (VBMP) digital terrain files are available by selecting "VGIN Hosted Downloads" at the top right of https://vgin.maps.arcgis.com/apps/PublicGallery/index.html?appid=d08a08ad5567483a903c34d6553e8ace#! and then clicking "2002 VBMP TINs."
31 More information on VITA is available at https://www.vita.virginia.gov/.
32 23 CFR 772.11 states that new developments must be at least in the permitting stages to be considered for noise mitigation.
33 Radford University's spatial data server is available at https://www.radford.edu/content/csat/home/gis-center.html.
34 For more information on WSDOT’s noise program, see https://wsdot.wa.gov/construction-planning/protecting-environment/noise-walls-barriers.
35 Linear referencing systems measure the relative distance of features along a linear pathway, such as a roadway.
36 WSDOT's GeoData Distribution Catalog is available at https://gisdata-wsdot.opendata.arcgis.com/.
37 More information on the Workbench is available at https://wsdot.maps.arcgis.com/home/webmap/viewer.html. Additional information on TransMapper is available at https://wsdot.wa.gov/about/transportation-data/statewide-gis-maps-data-layers.
38 66 decibels or greater is FHWA's criterion for what constitutes an "impacted location."

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APPENDIX A: LIST OF INTERVIEW PARTICIPANTS

Agency Name* Title Phone Email Address
FHWA
Adam Alexander   202-366-1473 adam.alexander@dot.gov
Mark Ferroni   202-366-3233 mark.ferroni@dot.gov
Mark Sarmiento   202-366-4828 mark.sarmiento@dot.gov
Volpe Center
Jaimye Bartak Transportation Analyst
Alisa Fine Community Planner 617-494-2310 alisa.fine@dot.gov
Caltrans
Jim Andrews Senior Transportation Engineer 916-653-9554 jim.andrews@dot.ca.gov
Lefteris Koumis Senior Transportation Engineer 916-653-0053 lefteris_koumis@dot.ca.gov
Florida DOT
Mariano Berrios Environmental Programs Administrator 850-414-5250 mariano.berrios@dot.state.fl.us
Pete McGilvray Environmental Quality Performance Administrator 850-414-5330 peter.mcgilvray@dot.state.fl.us
Matt Muller Technology Resource Manager 850-414-5329 matthew.muller@dot.state.fl.us
Maryland SHA
Ken Polcak Noise Abatement Design & Analysis Team Leader 410-545-8601 kpolcak@sha.state.md.us
Mike Sheffer Assistant Division Chief / GIS Coordinator 410-545-5537 msheffer@sha.state.md.us
North Carolina DOT
Joe Rauseo Acoustic Engineer 919-707-6084 jarauseo@ncdot.gov
Ohio DOT
Noel Alcala Noise and Air Quality Coordinator 614-466-5222 Noel.alcala@dot.state.oh.us
Craig Ayers Noise and Air Quality Intern 614-995-2187 craig.ayers@dot.state.oh.us
Gary Penn GIS Coordinator 614-466-7100 gary.penn@dot.state.oh.us
Tennessee DOT
Jim Ozment Manager, Social and Cultural Resources Department 615-741-5373 jim.ozment@tn.gov
Ann Epperson Transportation Manager 1 615-253-2470 ann.epperson@tn.gov
Virginia DOT
Geraldine Jones CEDAR Administrator / Environmental GIS Coordinator 804-786-6678 Geraldine.Jones@vdot.virginia.gov
Tiffany Abbondanza   804-371-4954 tiffany.abbondanza@vdot.virginia.gov
Paul Kohler Air Quality, Noise & Energy Section Manager 804-371-6766 Paul.Kohler@vdot.virginia.gov
Josh Kozlowski Noise Abatement Specialist 804-371-6829 Joshua.Kozlowski@vdot.virginia.gov
Washington DOT
Larry Magnoni Air and Acoustics Specialist 206-440-4544 Larry.Magnoni@wsdot.wa.gov
Tim Sexton Air/Acoustics/Energy Policy Manager 206-440-4549 Timothy.Sexton@wsdot.wa.gov
Jim Laughlin Air/Acoustics/Energy Technical Manager 206-440-4643 Jim.Laughlin@wsdot.wa.gov
Elizabeth Lanzer Program Manager, Environmental Information 360-705-7476 Elizabeth.Lanzer@wsdot.wa.gov
Kathy Prosser GIS/GPS Specialist 360-705-7498 Kathy.Prosser@wsdot.wa.gov

*Bolded name indicates participation in both interviews and the peer exchange.


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APPENDIX B: PEER EXCHANGE AGENDA

Goal: Share lessons learned, best practices, and challenges in using GIS to support noise modeling and analysis.

Monday, April 23
1:00 – 1:30 Welcome, Introductions, and Background FHWA (Adam Alexander and Mark Sarmiento) and Tennessee DOT
1:30 – 2:30 Overview of FHWA GIS and Noise Activities FHWA
Break
2:45 – 3:45 Demonstrations/Presentations 1
  • Tennessee DOT – Type II Inventory/Spreadsheet
  • Caltrans – Sound Wall Inventory
3:45 – 4:45 Roundtable 1: Reporting - All Participants
  • What are the potential uses and purposes of a sound wall inventory (including and beyond meeting 23 CFR 772 requirements)?
  • How does GIS support developing sound wall inventories? What are the benefits and challenges?
  • What types of data and maintenance are involved with developing a sound wall inventory?
4:45 – 5:00 Day 1 Key Points/Wrap-Up FHWA
6:00 Informal Dinner (Big River Restaurant - 111 Broadway, Nashville, TN 37201)
Tuesday, April 24
8:00 – 8:15 Day 1 Re-cap FHWA
8:15 – 9:15 Demonstrations/Presentations 2
  • Florida DOT – Efficient Transportation Decision-Making Process (ETDM) and Environmental Screening Tool (EST)
  • North Carolina DOT – Use of GIS for Decibel Tolerance Levels
9:15 – 10:15 Roundtable 2: Data - All Participants
  • What types of data have helped support successful noise assessments/activities?
  • How does/can GIS play a role in helping gather, collect, and/or maintain data?
  • What are best practices for using GIS for these purposes?
  • How can Google/Bing (or other mapping applications) support noise assessments?
Break
10:30 – 11:15 Roundtable 3: Applying GIS/Geospatial Data to Assess Noise
  • How can GIS be better integrated into TNM/modeling? Should it be?
  • What are other uses for GIS or geospatial data in assessing or mitigating noise (e.g., project-level screening, identifying contours, wildlife impacts)?
  • Can States share any examples? What are the benefits, challenges, and lessons learned?
11:15 – 11:45 Demonstrations/Presentations 3 Ohio DOT- Noise Barrier Inventory/Use of GIS for Traffic Noise Model
Lunch
12:45 – 1:45 Demonstrations/Presentations 3 (continued)
  • Maryland SHA – Noise Complaint Inventory
  • Washington DOT – Planned GIS Screening Layer/TransMapper Tool
1:45 – 2:30 Roundtable 4: Assessing Potential for GIS in Noise Assessments – All Participants
  • How does/could GIS help States respond to current (or new) FHWA noise requirements?
  • What are the benefits and challenges of GIS in doing so?
  • What funding/training or other resources are needed to make the most of GIS in noise applications?
  • How can staff effectively translate the benefits of GIS to agency leadership?
2:30 – 2:45 Day 2 Key Points/Wrap-Up FHWA
2:45 Adjourn  


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APPENDIX C: PEER EXCHANGE ROUNDTABLE QUESTIONS

Roundtable 1: Reporting

Roundtable 2: Data

Roundtable 3: Other Applications of GIS/Geospatial Data to Assess Noise

Roundtable 4: Assessing Potential for GIS in Noise Assessments


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APPENDIX D: ADDITIONAL RESOURCES

This appendix includes examples of resources that support GIS tools for noise. FHWA does not endorse any specific resource.


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APPENDIX E: SELECT STATE DOT APPLICATIONS OF GIS FOR NOISE

State Developed GIS/Geospatial Noise Barrier Inventory Use GIS for Project Screening, Planning & Programming for Noise Issues Use GIS Data/Tools in TNM Modeling Developed or Uses Enterprise or Web-Based GIS Tool Use Web-Based GIS Mapping Service (i.e. Google, Bing) Log Noise Complaints Geospatially Use GIS for Noise-Related Communication with the Public Other
Caltrans Yes (includes video) No No Yes (developed noise barrier mapping tool using ESRI FlexViewer) Yes (for reference purposes, and for integration into noise wall inventory) No Yes (noise barrier tool publicly accessible)  
FDOT Yes (retrofitting existing inventory to respond to 23 CFR 772) Yes (noise issues are considered as an aesthetic issue in a statewide web-based GIS tool in the planning/programming phases for all major transportation projects) No Yes (FDOT Environmental Screening Tool) No No Yes (ETS publicly accessible)  
MDSHA Yes (under development) No No Yes (developing noise barrier tool for MD iMap) Yes (for reference purposes) No Yes (MD iMap publicly accessible)  
NCDOT No Yes (uses GIS data to complete TNM noise models for all project alternatives) Yes (uses GIS extensively for input into TNM model) Yes (uses NC One Map, a statewide GIS repository, to obtain GIS data) No No No Overhauled & updated traffic noise policy to formalize use of GIS in TNM modeling; uses GIS to design noise walls.
ODOT Yes (georeferenced walls in spreadsheets) No No No Yes (uses Google to obtain noise barrier coordinates) No Yes (to locate noise complaints)  
TDOT Yes (under development) No Yes (uses GIS data on a project-by-project basis) Yes (TNM, but noise barrier data not yet included) Yes (for reference purposes) No No (plans to do so in the future)  
VDOT Yes (currently updating old database) No Yes Yes (the noise barrier layer is available in Integrator) Yes (for reference purposes) No (under consideration) No Uses GIS to supplement project data (beyond highway rights of way) and to aid with the evaluation of TNM predicted sound levels and design of noise barriers; used to develop graphics for noise reports.
WSDOT Yes (includes proposed and existing noise barriers) Yes (developing a GIS-based model that uses traffic data along with noise emission curves to identify rudimentary noise impact areas for preliminary screening purposes) No Yes (WSDOT's Workbench includes all agency GIS data, including some noise-related data) Yes (for reference purposes) No Yes (existing and proposed noise barriers available online) Develop graphics of noise wall locations; develop maps for noise discipline reports generated to meet NEPA requirements


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APPENDIX F: REQUIRED NOISE BARRIER INVENTORY DATA

As outlined in 23 CFR 772, FHWA requires State DOTs to submit (on a triennial basis) the following information on noise barriers:


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