A field technician checks the width of a sidewalk for compliance with ADA guidelines. Photo: Shawn Devereaux
GIS was used to manage ADA non-compliance and prioritize construction and maintenance projects. Non-compliance sidewalk locations are displayed as red flags. Source: Andrew Rudin

The engineering firm developed a proximity analysis scoring matrix to rank potential new sidewalk construction projects based on each gap in the sidewalk network's spatial proximity to pedestrian attractors and risks. This matrix assigned point values for each type of attractor and risk that is within a ¼-mile radius. Pedestrian attractors include schools, transit stops, major employers, public parking lots, government offices, parks, and places of interest. Pedestrian risks include pedestrian-vehicle accident locations and streets classified as collectors and higher.

LAN developed a custom geographic information system (GIS) toolset called the Pedestrian Infrastructure Management System (PIMS) that programmatically scores all locations. A cumulative score is assigned to each location based on the total number of attractors and risks identified within the search radius.

The consultant also performed a field assessment of sidewalks and curb ramps to determine specific locations that were non-compliant with ADA accessibility criteria. By using a global positioning system (GPS) enabled data collector, all field data was easily integrated into the GIS database for use in the PIMS toolset.

ADA is very black and white on accessibility standards. Infrastructure is either compliant or it's non-compliant. For this project, if a sidewalk segment contained a single non-compliant location or a curb ramp didn't meet a solitary criterion, the entire feature was deemed non-compliant. By adhering to this strict interpretation of ADA accessibility guidelines, the city eliminates biases or assumptions regarding accessibility.


While performing the field assessment for ADA compliance, public works staff also graded the current condition of sidewalks and curb ramps. A condition worksheet had been developed and used by city staff to help identify maintenance requirements. This worksheet was redesigned to work within the GPS interface so the field technicians could collect data while determining ADA compliance.

Maintenance condition data, easily integrated into the GIS, also are weighed against a scoring matrix to determine locations that are high, medium, and low priority for rehabilitation.

Once the GIS database is complete with proximity analysis data, the ADA field assessment data, and the maintenance condition data, a prioritization routine is used to calculate a cumulative score for each location. These scores are then categorized as high, medium, or low priority within a constraining boundary.

For the first phase of the project, 16,000 potential construction locations were scored in a few hours when previously, staff had spent up to one hour determining the priority of a single location. Using this process, the public works department is able to produce an unbiased list of high-priority project locations from which actual projects are culled. The use of the high-priority list has significantly reduced the staff time required for researching sidewalk requests for locations that ultimately ranked as low priority.

Phase II is currently underway, which includes expansion of the analysis and field assessment to a majority of the city. Also, LAN is developing an Internet-based address-to-address travel route mapping application that will return a travel path similar to MapQuest, but instead of street directions, it will integrate the city's pedestrian infrastructure with transit data (bus stops and bus routes) to provide an intermodal travel planning tool. In addition to a travel route, the application will provide a list of sidewalk and curb ramp locations that are non-compliant with ADA standards. This application will be of significant value to pedestrians, not only for trip planning, but also for making informed decisions on whether a route is ADA accessible.

— Devereaux is GIS manager with Lockwood, Andrews & Newnam Inc., Austin, Texas, and Curtis is the program manager of the pedestrian and bike program with the city of Austin.