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  • 1. 1 Pedestrian Infrastructure on the Public Right-of-Way: Aging Pedestrians and 2 Prioritizing Sidewalk Hazards Using the Ultra Light Inertial Profiler (ULIP) 3 4 5 6 7 8 9 10 11 12 13 14 15 16 November 10, 2011 17 18 4,112 words 19 3 Figures 20 21 22 23 24 25 26 27 28 29 Corresponding Author 30 Mr. Arfaraz Khambatta, CASp 31 Director, Access Consulting 32 Sally Swanson Architects 33 220 Sansome St., Suite 800 34 San Francisco, California 94104 35 Phone: 4154453045 36 Fax: 415 445 3055 37 Email: ssa@swanarch.com 38 39 Mr. Franz Loewenherz 40 City of Bellevue 41 450 110th Ave. NE 42 P.O. Box 90012 43 Bellevue, Washington 98009 44 Phone: 425-452-4077 45 Email: FLoewenherz@bellevuewa.govTRB 2012 Annual Meeting Paper revised from original submittal.
  • 2. Khambatta & Loewenherz 2 1 ABSTRACT 2 Walkability is an important criterion of livable communities and has been tied to health and social 3 benefits. New planning concepts reducing car dependency will increase senior resident’s time on 4 sidewalks. While cities are required by ADA laws to reduce sidewalk hazards, the time and cost of 5 gathering exact data has been a deterrent. The typical sampling of elements such as sidewalks, curb 6 ramps, pedestrian crossings, and obstructions do not provide an adequate understanding of the 7 hazards and barriers throughout a district. In particular, prioritizing the most critical sidewalk hazard 8 locations for city maintenance is not organized and tied to other street maintenance plans. A new and 9 innovative tool, the ULIP, developed through the Federal Highway Administration, allows 100% 10 sidewalk inventory and converts the data into a city’s GIS system. Knowing exactly the location and 11 severity of sidewalk barriers increases the likelihood that all hazards are addressed, reducing the potential 12 for falls and accidents. This innovative technology is now being tried in five cities. In the future, time and 13 cost savings could be accrued, treating ADA code requirements on a regional rather that a city scale. As 14 cities plan for greater sidewalk use by a new generation of aging residents, they can reduce potential 15 accidents and the possibility of increased litigation. 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50TRB 2012 Annual Meeting Paper revised from original submittal.
  • 3. Khambatta & Loewenherz 3 1 WALKABLE COMMUNITIES 2 Livable communities are walkable communities; the two go hand in hand. Decreasing the time residents 3 spend in their cars and increasing the time they spend walking is a component found on the agendas of 4 city governments to create a better quality of life in their communities. Popular movements, 5 organizational and government campaigns, including New Urbanism (www.cnu.org), the Center for 6 Disease Controls’ Healthy Communities (www.cdc.gov), the American Institute of Architect’s livable 7 communities (www.aia.org) and many others, place a new unprecedented focus on the walking 8 environment. 9 Many of the requirements for safe and accessible sidewalks already exist as required codes. The 10 Americans with Disabilities Act (ADA) of 1990 provided civil rights protection to those with disabilities; 11 amendments since that time have extended those rights to cover access to services, which includes 12 accessible sidewalks. These code requirements are mandatory for cities and counties to uphold (1), 13 although time and budget constraints have often turned compliance into a reactive endeavor through ADA 14 complaints and litigation. Research exists documenting the need of improved sidewalk accessibility, 15 particularly for seniors (2). 16 America’s growing senior population has been a spur for the creation of walkable communities. 17 Within 20 years, the US Census Bureau estimates that more than 19% of Americans will be over the age 18 of 65 (3). The American Association of Retired Persons (AARP), in their definition of livable 19 communities, includes affordable and appropriate housing, supportive community features and services, 20 and adequate mobility options. On AARP’s Evaluation Guide for Livable Communities, walkability is an 21 important element with 20 criteria listed for rating. 22 Walkability is a key requirement for livable communities because walkable communities have 23 been linked to many health benefits. Studies show that physical activity, such as walking, can extend 24 older persons’ independent life, lower death rates, and reduce costs of health care. Investing money in 25 creating a more walkable community brings large returns in terms of health and social benefits. A report 26 from the United Kingdom (4) lists walking as lowering death rates by 20%, reducing cardiovascular 27 disease up to 30%, and reducing the risks of high blood pressure and cholesterol, aside from exercise 28 helping to reduce weight. The positive impact on mental health, and social connection to a community, 29 has also been researched (5), as well as it being an alternative that provides a safer mode of mobility to 30 the aging than driving. 31 In AARP’s livability survey, walkability criteria includes a number of factors, among them are 32 ratings for sidewalk maintenance, appropriate curb cuts and sidewalk obstructions. The need to reduce 33 sidewalk hazards, particularly for seniors, underlies their greater susceptibility to falls. Each year, 34 Americans who are 65 and over fall, and a third of the falls cause injuries requiring medical 35 treatment. The leading cause of injury deaths for those 65 and over are falls and about half of those 36 resulted in traumatic brain injuries (6). As cities emphasize walking for health and spending more time 37 out of doors, creating a safe walkable environment for seniors becomes critical. 38 39 THE ULIP 40 The ADA requires state and local governments to prepare a Self-Evaluation Plan to identify all 41 access issues. Public agencies are required to develop a Transition Plan to identify and schedule the 42 removal of barriers to their programs and facilities. But regularly updating transition plans for pedestrian 43 facilities on public rights of way (such as curb ramps and sidewalks) is challenging. 44 In the traditional approach, sidewalk measuring is a labor intensive task. One person walks down 45 the sidewalk, placing a level at a prescribed distance, usually every two to four feet, measuring the 46 running slope (slope in the direction of travel), cross slope (slope perpendicular to the direction of travel), 47 and slab-to-slab faulting inventory assessment. On average, measuring covers less than one mile per hour. 48 The many digital images and measurements that result can make assessing compliance difficult when 49 referencing then from a desk at a later point in time. 50 Due to the high cost, length of time, and complexity of conducting accurate measurements, many 51 agencies find that they cannot feasibly complete a 100% inventory; instead they conduct samplings andTRB 2012 Annual Meeting Paper revised from original submittal.
  • 4. Khambatta & Loewenherz 4 1 extrapolate. Often 2 approximations, the data can 3 also be out of date because 4 budget limitations preclude 5 updating on a regular basis. 6 A new alternative 7 methodology is based on an 8 inertial profiler system that 9 had been in use since the 10 1970s to measure defects 11 on highway and airport 12 pavement surfaces. The Ultra- 13 light Inertial Profiler (ULIP) 14 system was designed and 15 developed by Starodub, Inc. in 16 Kensington, MD, under 17 contract with the Federal 18 Highway Administration, 19 which is responsible for 20 ensuring access to pedestrian 21 facilities within the public 22 right-of-way. 23 The innovative 24 system, mounted on a Segway 25 HT scooter, has both sensor 26 and data acquisition 27 components. The device’s 28 laser measurement system, 29 three accelerometers, and 30 gyroscope measure the 31 sidewalk profile at a rate of 32 10,000 records of data per 33 second. Together, these 34 devices enable the capture of 35 highly accurate location- 36 specific information about Figure 1: Accessibility Consultant performing surveys on the ULIP. 37 sidewalk slope and small surface 38 variations that can make a 39 sidewalk difficult to navigate (7). The accompanying software is compatible with a City’s asset 40 management database and Geographic Information Systems (GIS). 41 Using the new Segway approach, one person is able to measure, in more detail than the traditional 42 method, six miles of sidewalk per hour. The ULIP is therefore a cost-effective solution for inventorying 43 and mapping the degree to which sidewalks and curb ramps meet ADA standards. Also advantageous is 44 that the ULIP allows 100% data collection rather than samplings, resulting in accurate information for any 45 sidewalk within the measurement boundaries. 46 47 GIS INTEGRATION 48 The ULIP uses ESRI ArcPad to automatically record the exact position of access barriers using the 49 inertial navigation system. That information is then plugged into a GIS computer system to store, analyze,TRB 2012 Annual Meeting Paper revised from original submittal.
  • 5. Khambatta & Loewenherz 5 1 compare and display the information. The raw ULIP data is first imported into ArcGIS which turns the 2 surveyed route into a digital rendering. 3 Once the field data collection and validity checks are performed, the raw data is calibrated and processed 4 so it can be analyzed. The data is associated to GIS layers, each representing one of several characteristics 5 and linked to geographic points. For example, the ULIP measurements are one layer, curb ramps and 6 pedestrian signals would each have a layer as well. GIS is used to overlap the data layers and determine 7 the cumulative intensity of all characteristics throughout the area measured. 8 9 Technical Infeasibility Analysis 10 Among the barriers measured are those sidewalk areas that are deemed “technically infeasible.” Side walk 11 grades, per ADAAG standards, should not be greater than five percent. But sidewalks follow the existing 12 topography and the slope doesn’t always meet the ADA guidelines. If a City is able to document the issue 13 as technically infeasible because of the existing grade of the adjacent street, it can greatly reduce the 14 amount of non-compliant barriers which the City is responsible for mitigating. 15 16 ADA Activity Ranking 17 Sidewalk Data Aggregation involves converting all the data from the various sidewalk related datasets 18 into attributes which are then attached to each individual sidewalk feature. This is an intermediate step for 19 barrier ranking and the mapping interface required to create an ADA dataset. When completed, activity 20 scores for each ADA feature are assigned. Pedestrian facilities heavily used are assigned a higher priority 21 for repairs than those which are not as often used. A variety of spatial data characteristics such as socio- 22 economic data, transit routes and stops, arterial classifications, housing and employment density, and 23 others, are used to assess each feature and assign it a score. A key feature of this GIS-based ranking tool 24 is a user-friendly interface which allows City staff to assign different weights to the various criteria and 25 re-run the analysis in order to iteratively refine the analysis as needed. 26 27 ADA Impedance Scoring 28 Scores are determined for each ADA feature based upon the field data collected. A sidewalk with large 29 portions of non-compliant slope and grade, or with numerous obstructions, would be assigned a higher 30 priority for repairs than one with few issues. User-friendly interfaces allow City staff to adjust weights 31 and try different scoring scenarios to validate the scoring strategy. 32 33 34 Figure 2: Prioritizing data to achieve barrier rankingTRB 2012 Annual Meeting Paper revised from original submittal.
  • 6. Khambatta & Loewenherz 6 1 Final Prioritization scoring. 2 The c activity and impedance scores from the above tasks are combined to create the final prioritization 3 score for each feature. 4 5 A City then has the option to use the created data layers on their existing computer system or through a 6 GIS viewer where all information could be accessed from a dedicated web page. This browser-based GIS 7 Viewer is a lightweight, fast application which allows for basic viewing and reporting on the ADA dataset 8 through ArcGIS Server web application & documentation. The application’s basic features and 9 functionality: 10 • A set of cached base map services such as Bing Maps, aerial photography or similar, with 11 interface for toggling visibility between them 12 • A custom cached map service displaying data from the City’s GIS database, such as city 13 limits, landmarks, or similar 14 • A dynamic map service showing the ADA data 15 • Standard map navigation tools 16 • A Table of Contents widget allowing user to turn on or off individual ADA data layers 17 • Address search functionality allowing user to enter an address and zoom to it on the map 18 • Identify functionality, allowing user to click on an ADA feature to get attributes, photo or 19 hyperlink, etc 20 21 Staff training in the use of the barrier ranking tool and browser-based mapping interface would be 22 important to achieve the best results. 23 24 25 26 Figure 3: Diagram showing the process of how the ULIP works (Courtesy of F. Loewenherz).TRB 2012 Annual Meeting Paper revised from original submittal.
  • 7. Khambatta & Loewenherz 7 1 THE CITY OF BELLEVUE – REDUCING COSTS 2 The customized ULIP system was implemented through a pilot program in the City of Bellevue. The city 3 has a population of 120,000 residents, with approximately 15 percent living with a variety of disabilities 4 and 13.4 % of the population over the age of 65. In 2006, the City initiated an update to their ADA 5 transition plan documenting existing physical barriers for persons with disabilities. Bellevue considered a 6 number of options for gathering data on its 336 miles of sidewalk and 4,000 curb ramps. Based on 7 preliminary tests using existing options, the City concluded that the cost could be $1 million at a 8 minimum (8). 9 Hearing about the profiler technology, an interdepartmental City team partnered with federal and 10 regional agencies to adapt it to their needs. In 2006, the FHWA’s Office of Pavement Technology funded 11 Starodub to provide the City of Bellevue with a ULIP and support. Additional FHWA funding was 12 provided in 2007 for software refinements. 13 Bellevue’s city staff managed a three-agency partnership, including Transportation and IT 14 Departments, to field test versions of the technology, and developed programming to synthesize ULIP 15 data records into the citys GIS system. 16 King County, a transit operator in the region, provides ADA curb-to-curb para-transit service, 17 used extensively by the elderly. The service is a safety net for those whose disabilities prevent use of 18 fixed route bus service. Bellevue consulted with the Department of Accessible Services to ensure that the 19 ULIP technology would save time and money that would otherwise be spent conducting accessible 20 pathway assessments. King County subsequently provided support for two staff members involved in the 21 inventory process. 22 The City of Bellevue sought confirmation that data acquired from the ULIP platform was 23 reproducible and accurate as it was a new system. In 2007, during the trial period, Bellevue and 24 Starodub, Inc. staff undertook numerous tests comparing grade and cross slope measurements from the 25 ULIP and alternative measurement devices (e.g., digital smart level readings) before a decision was made 26 to employ this technology citywide. Bellevue testing with global navigation satellite system (GPS) found 27 the accuracy of latitude/longitude data degraded in areas with tall buildings or thick tree canopies. After 28 evaluating alternative approaches a sensor-based inertial navigation system integrated with an ESRI 29 ArcPad interface was selected to enhance the accuracy of the spatial data in the inventory. To establish 30 travel path control points, field technicians entered the start and end points for each data collection run on 31 an ortho-photo image on the ULIP’s notebook computer screen. The gyroscope, accelerometers and 32 distance measurement instrument in the sensor box were used to compute the ULIP’s relative path of 33 travel. The relative travel path was combined with the control points to produce a travel path consistent 34 with the city’s GIS system (9). 35 The ULIP technologys efficacy was further tested by the City in 2008, when two interns 36 (supported by King County Metro’s contribution) were able to inventory the entire citys pedestrian 37 system, across 33.9 square miles, within a few months. GIS systems organized the millions of data points 38 generated during the study and were instrumental in developing a web-based mapping interface for asset 39 management and compliance monitoring. For technical infeasibility, City of Bellevue staff developed a 40 GIS script that enabled a comparison of every non-standard sidewalk segment to the grade of the adjacent 41 roadway. Adjacent roadway grade profiles were derived from a digital elevation model, a representation 42 of ground surface topography. Criteria were then used to filter out 95 miles of non-standard sidewalk 43 grade locations deemed technically infeasible. 44 The resulting ADA sidewalk and curb ramp self evaluation is documented on the City’s intranet. 45 This internal web interface maps all non-standard data points related to curb ramp location and 46 compliance rating – at the block face level, including sidewalk obstructions, heaving, running slope, and 47 cross slope. Additional functionality of this geospatial database includes the ability to search and/or turn 48 off certain barrier types and generate reports of the barrier information. 49 50TRB 2012 Annual Meeting Paper revised from original submittal.
  • 8. Khambatta & Loewenherz 8 1 The ADA viewer interface creates a platform from which city staff will retrieve information on 2 ADA barriers in the public right of way, informing the following accessibility programs: 3 • New Development: New development or redevelopment projects must include sidewalks 4 and curb ramps. 5 • Citizen Request Program: Citizens submit requests to have a new curb ramp installed or 6 have an existing curb ramp repaired at any location within the City. 7 • Annual Installation, Repair, and Maintenance Program: The City’s Transportation 8 Department repairs sidewalks and installs new curb ramps annually as part of routine 9 maintenance. 10 • Street-Related Capital Improvement Projects: Sidewalks and/or curb ramps are installed 11 and/or repaired in all street-related capital improvement projects (e.g., street widening or 12 other street upgrades). 13 14 The total cost of the citys ADA inventory effort - from technology development to complete data 15 set - was $285,000, a 70 percent cost savings over the original estimate to conduct a traditional survey (8). 16 The project began in 2008 and concluded in 2009. 17 As a new technology, the City of Bellevue sought confirmation that data acquired from the ULIP 18 platform was repeatable, reproducible, and accurate. Numerous tests were carried out comparing grade 19 and cross slope measurements from the ULIP and alternative measurement devices (e.g., digital smart 20 level readings). Bellevue and Starodub staff undertook a rigorous review of this data before a decision 21 was made to employ this technology in a citywide inventory effort. During the citywide inventory effort, 22 the city employed quality assurance and quality control protocol for validation testing of the software and 23 hardware. The City of Bellevue advanced the ULIP platform and cities now using this system realize 24 additional cost-savings because the technology has already been field tested and refined. 25 After development and testing, the ULIP platform is the first technology of its kind that enables 26 jurisdictions to quickly and accurately complete an ADA condition assessment inventory. Bellevue’s 27 project was identified as a best practice (10). 28 The ULIP system is now being utilized by the firm of Sally Swanson Architects in the following 29 county and cities: 30 31 32 33 34 County of St. Louis, MO 35 Large Scope 36 The County, with 992,000 residents of which almost 15% are over the age of 65, has a prohibitively large 37 number of lineal miles of sidewalk across 524 square miles. Data collecting, using the ULIP, is being 38 divided into phases, with Phase I covering 80 linear square miles of sidewalks on arterials and collectors. 39 The project began in 2011 and will conclude in 2013. 40 41 The City of San Carlos 42 Topographic Impassibility 43 The City of San Carlos, with a population of 28,500 residents of which over 14% are over 65 years old, is 44 located between San Francisco and San Jose, among hilly terrain. The City has technical and 45 topographical infeasibility issues in meeting ADA compliance on 120 miles of sidewalk within six square 46 miles. The accuracy of the ULIP will allow pinpointing where a sidewalk slope would not be able to be 47 fixed because of the steepness of an existing hill. Digital elevation models created by the city overplayed 48 on the ULIP models in GIS reveal slopes along adjacent roadways that match with sidewalks, which can 49 then be labeled technically infeasible. The project began in 2011 and will conclude in 2012. 50TRB 2012 Annual Meeting Paper revised from original submittal.
  • 9. Khambatta & Loewenherz 9 1 The City of Clovis, CA 2 DOJ requirements 3 The City, with a population of 95,650 is under a court ordered consent decree by the Department of 4 Justice, required to undertake a complete documentation of all their ADA barriers within the rights of 5 way. The ULIP is in the process of gathering field data on 638 linear miles of sidewalk over 23.3 square 6 miles. The project began in 2010 and will conclude in 2012. 7 8 The City of San Marcos, CA 9 Planning Tool 10 The City of San Marcos, with a population of approximately 85,000, is undergoing surveys of pedestrian 11 facilities within the public rights of way using the ULIP. Their engineering department was interested in 12 incorporating the data into their GIS system to be used as a scoping and planning tool (11). Rather than 13 static data, the City engineers will be able to sort and sift the field information instantaneously and over 14 time to incorporate it into the city’s overall maintenance plan. The project began in 2010 and will 15 conclude in 2011. 16 17 18 LESSONS LEARNED 19 Partnerships 20 Because agencies at all levels are required to respond to ADA mandates, developing partnerships 21 increases the cost-effectiveness of technology development and compliance efforts. In the City of 22 Bellevue, coordinated staffing and funding commitment from three participating agencies (Federal 23 Highway Administration, King County, and the City of Bellevue) made it possible to undertake 24 Bellevue’s proposal to assess the applicability of inertial profiling technology in identifying existing 25 facilities that limit access for persons with disabilities. 26 27 GIS 28 GIS can play an important role from data acquisition (i.e., organizing the millions of data points generated 29 during the study) to project prioritization (i.e., determining priorities for improvements and displaying the 30 corresponding locations on a variety of mapping interfaces. 31 32 Integration of improvements 33 The data inventory goal is to create a method of fixing barriers that is not haphazard but that bundles 34 similar requirements or areas to produce a prioritized improvement list that can be integrated into an 35 agency or city’s capital improvement programming. The results provide cost-effectiveness through 36 economies of scale and efficiency of delivery. In addition, the ULIP allows a priority ranking system of 37 the most severe hazards, allowing them to be addressed first. 38 39 New Possibilities on a Regional Scale 40 For over twenty years, city and counties have had the legal obligation of providing accessible sidewalks 41 free of barriers. But agencies did not have a tool that allowed them to be proactive in accessing all 42 barriers. With the ULIP’s ability to identify scope, a budget reflecting the specific barriers that need 43 immediate attention can be folded into capital improvement projects and incorporated into GIS systems. 44 The ULIP is an important component of this streamlined process for access. 45 A rising population of elderly coupled with alternative planning movements for more walkable 46 communities have made sidewalk safety an important issue. Walkable communities have been largely a 47 district endeavor, because there has been little cost incentives to include larger areas. The ULIP opens the 48 possibility of addressing sidewalk compliance as one issue of walkability on larger scales, even 49 regionally. There is a cost advantage of gathering field data over many miles. 50 While cities and towns strive to each have their walkable but fragmented areas, without much 51 planning towards regional connectivity (12), cooperatively and collaboratively addressing the issues mayTRB 2012 Annual Meeting Paper revised from original submittal.
  • 10. Khambatta & Loewenherz 10 1 truly help in creating walkable communities. Pooling of resources could also ease the task of rights of 2 way maintenance, which is time consuming and costly. As a greater percentage of the population ages, 3 rising to 1 out of 5 Americans over the age of sixty-five by 2040 (3), and city budgets are strained, while 4 more and more plan for walking environments, adhering to ADA access requirements need not fall 5 through the cracks. 6 7 8 ACKNOWLEDGEMENT 9 The FHWA supported Starodub, Inc, in their development of the ULIP. Initially invented to measure 10 roughness on newly poured concrete pavements for the FHWA, the device proved to be easily 11 transportable and could access sidewalks. Therefore, the ULIP was adapted to sidewalk accessibility and 12 measurement of smoothness. Starodub completed initial validation testing, then provided technical 13 support for prototype evaluation trails. The first field tests took place in 2004 and refinements continued 14 to 2009. The authors thank Dorit Fromm for her research assistance and contribution to this work. 15 16 17 18 19 20 21 REFERENCES 22 23 1. Americans with Disabilities Act Code of Federal Regulations. Part 35 - Nondiscrimination on the 24 Basis of Disability in State and Local Government Services. Chapter 1 of Title 28, (CFR). 25 26 2. Kockelman, K., L. Heard, Y. J. Kweon, and T. Rioux. Sidewalk Cross-Slope Design: Analysis of 27 Accessibility for Persons with Disabilities 2.In Transportation Research Record: Journal of the 28 Transportation Research Board, No. 1818, Transportation Research Board of the National Academies, 29 Washington, D.C., p109 30 31 3. National Population Projections. Percent Distribution of the Projected Population by Selected Age 32 Groups and Sex for the United States: 2010 to 2050. U.S. Census Bureau. NP2008- 33 T3. www.census.gov/population/www/projections/summarytables.html. Accessed July 20, 2011. 34 35 4. Sinnett, Dr. D., K. Williams, Dr. K. Chatterjee, Dr N. Cavill. Making the Case for Investment in the 36 Walking Environment A Review of the Evidence. Department of Planning and Architecture, Faculty of 37 Environment and Technology, University of the West of England, Bristol BS16 1QY, June 2011. 38 39 5. Leyden, K.M. Social Capital and the Built Environment: The Importance of Walkable Neighborhoods. 40 American Journal of Public Health, Vol. 93, No. 9, 2003, pp. 1546-1551. 41 42 6. Thomas, K.E., J.A. Stevens, K. Sarmiento and M.M. Wald. Fall-Related Traumatic Brain Injury 43 Deaths and Hospitalizations Among Older Adults – United States, 2005. Journal of Safety Research, 44 Vol. 39, No. 3, 2008, pp. 269-272. 45 46 7. Starodub User’s Guide: Procedures using ULIP-ADA System. Starodub 2011, pp 1-90. 47 48 8. Loewenherz, F. Asset Management for ADA Compliance Using Advanced Technologies. Journal of 49 Public Works and Infrastructure, Vol. 2, No. 3, 2010, pp241-253. 50TRB 2012 Annual Meeting Paper revised from original submittal.
  • 11. Khambatta & Loewenherz 11 1 9. City of Bellevue. Toward Universal Access: Americans with Disabilities Act Sidewalk and Curb Ramp 2 Self-Evaluation Report for the City of Bellevue. September 2009, p 12. 3 4 10. Quiroga, C, S. Turner. ADA Compliance at Transportation Agencies: A Review of Practices. 5 Texas Transportation Institute, The Texas A&M University System, Texas 2008 based on a study for the 6 TRB: Asset Management Approaches to ADA Compliance. NCHRP 20-07 Task 249, National 7 Cooperative Highway Research Program. 8 9 11. Schlossberg, M. From TIGER to Audit Instruments: Measuring Neighborhood Walkability with 10 Street Data Based on Geographic Information Systems. Transportation Research Record: Journal of the 11 Transportation Research Board, No. 1982, 2006, pp. 48-56. 12 13 12. Canepa, B. Bursting the Bubble Determining the Transit-Oriented Development’s Walkable Limits. 14 Transportation Research Record: Journal of the Transportation Research Board, Vol. 1992, 2007, pp.28- 15 34. 16 17 18 19TRB 2012 Annual Meeting Paper revised from original submittal.

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