Transit corridors require specialized detectable warning surface (DWS) installation at every boarding and alighting area, curb ramp, and platform edge — making them among the most demanding ADA compliance environments for paver contractors. Unlike a standard sidewalk repair, transit stop DWS work must coordinate with live bus operations, tight boarding zone dimensions, and strict PROWAG R305 specifications for truncated dome geometry and color contrast. This case study examines a transit corridor DWS upgrade project along a major Indianapolis bus route serving 18 stops in need of full remediation. The project illustrates the assessment methodology, product selection process from the INDOT Qualified Products List, installation sequencing around active service hours, and the compliance documentation package delivered to the transit agency. While presented as a composite case study to protect agency confidentiality, all technical parameters, product specifications, and regulatory references reflect real-world conditions and requirements applicable to IndyGo routes and comparable transit corridors throughout Central Indiana.
Project Background: Transit Corridor ADA Upgrade
The project involved a major Indianapolis bus corridor operated by IndyGo, the city's public transit authority. The corridor spans approximately 4.2 miles through a dense urban environment with 18 active transit stops requiring detectable warning surface upgrades. IndyGo's Red Line Bus Rapid Transit corridor, which opened in 2019 along College Avenue, established a high baseline for ADA-compliant stop design in Indianapolis — including high-platform boarding, level boarding access, and properly installed truncated dome DWS panels at every entry and exit point. The project corridor examined in this case study predates the Red Line and represents the older fixed-route bus infrastructure that still makes up the majority of IndyGo's network, where stop improvements have lagged behind the BRT flagship.
A Federal Highway Administration (FHWA) ADA compliance audit conducted as part of an INDOT self-evaluation process identified the corridor as a priority remediation target. Audit findings documented deteriorated DWS panels at all 18 stops: faded color contrast on safety yellow panels (measured at less than 70 percent luminance contrast against the surrounding pavement in several locations), truncated domes worn below minimum height thresholds, cracked and delaminated surface-applied panels, and two locations where DWS panels had been removed entirely during unrelated utility work and never replaced. The audit report triggered a mandatory remediation timeline under the transit agency's ADA Transition Plan, creating a procurement action for a qualified paver contractor to assess, specify, and install replacement DWS systems at all 18 stops within a single construction season.
Assessment and Product Selection
The assessment phase required a stop-by-stop condition survey of all 18 locations. At each stop, the field team documented existing DWS panel dimensions (width and depth in the direction of travel), measured color contrast using a calibrated luminance meter, assessed truncated dome height with a digital depth gauge, identified panel attachment failures or delamination, and recorded the dimensions of the accessible boarding zone including the clear floor space at the back-of-curb landing. This data was logged to a georeferenced site assessment form that became part of the compliance documentation package delivered to the transit agency upon project completion. Seven of the 18 stops presented additional complications: three had undergone informal asphalt patching by city maintenance crews that partially covered or displaced the existing DWS zone, and four had ADA boarding area dimensions that did not meet the minimum 5-foot by 8-foot clear space requirement — an issue requiring coordination with IndyGo's capital planning team before DWS installation could proceed.
Product selection was governed by two requirements: all materials had to appear on the INDOT Qualified Products List for detectable warning surfaces, and the selected system had to meet the color contrast specification for safety yellow against the dark gray concrete and asphalt paving present at most stops. After reviewing available QPL-approved options, the project specified a cast-in-place polymer composite panel system for stops with new concrete landings and a surface-applied epoxy composite panel for stops where the existing concrete substrate was in sound condition and did not warrant full curb ramp reconstruction. The cast-in-place system was preferred where construction activity allowed, as it eliminates the delamination risk that had contributed to the failure of the original surface-applied panels at several stops. The surface-applied epoxy system was selected for its minimal disruption footprint and shorter cure time — a critical factor at stops where service interruptions had to be kept to a single overnight window.
Installation Process
Installation sequencing was planned in close coordination with IndyGo operations, which required that no more than two adjacent stops be taken out of service simultaneously and that all stops be returned to accessible service before the start of the following day's first run. This constraint shaped the crew deployment strategy: a two-crew approach with one team handling saw-cutting and substrate preparation while a second team followed with panel installation and adhesive cure management. At stops requiring cast-in-place panels, the existing DWS zone was saw-cut to the manufacturer's specified panel dimensions — typically 24 inches in the direction of travel by the full width of the curb ramp — and the cut section was removed and replaced with fresh concrete. Panel anchors were set in the wet concrete and the polymer composite panel was set in place, leveled, and protected with temporary hoarding until the cure cycle was complete.
Surface-applied installations followed a five-step process: surface grinding to open the substrate and remove any residual adhesive from the previous panel, compressed-air cleaning to remove debris from the grinding process, primer application and 30-minute dwell time, two-part epoxy adhesive application to the panel back and substrate, and panel placement with mechanical tamping to ensure full contact and eliminate voids beneath the panel surface. Temporary construction fencing was deployed at each active work site to maintain a compliant accessible route around the installation zone, diverting pedestrians to an adjacent accessible path where one existed or providing a temporary asphalt ramp where the stop configuration required it. All installations used traffic control plans reviewed and approved by the Indianapolis Department of Public Works prior to the start of work.
Quality Assurance and Compliance Verification
Each completed DWS installation was subjected to a multi-point compliance verification before the stop was returned to service. Truncated dome geometry was verified using a calibrated digital depth gauge and a template gauge card: base diameter was confirmed at 0.9 inches (23 mm), top diameter at approximately 0.45 inches (11.5 mm), and dome height at 0.2 inches (5 mm) as specified in PROWAG R305.2.1 and the 2010 ADA Standards Section 705.1. Center-to-center dome spacing was verified at no less than 1.6 inches (41 mm) and no more than 2.4 inches (61 mm) in both the base-to-apex and diagonal directions. Color contrast was re-measured with the luminance meter at three points across each panel, with all readings required to show at least 70 percent luminance contrast between the panel surface and the immediately adjacent pavement. Slip resistance spot-checks using a pendulum slip resistance tester confirmed that all installed panels met the minimum 0.60 static coefficient of friction on the flat panel areas and 0.80 on any panels located within a ramp section.
Full PROWAG R305 compliance documentation was assembled for each of the 18 stops: the pre-installation condition survey, the product cut sheet and QPL listing confirmation, installation photographs at each process step, and the post-installation measurement record. Two stops required corrective action before sign-off: at one location a panel had been installed with the dome grid rotated 45 degrees relative to the direction of pedestrian travel, which was remediated by removing and reinstalling the panel at the correct orientation; at a second location a minor void beneath the panel edge was identified through tap-testing and addressed with injection epoxy before the stop reopened. The completed documentation package was submitted to the transit agency's ADA Coordinator and filed with IndyGo's internal ADA Transition Plan barrier remediation log.
Outcomes and Maintenance Plan
All 18 transit stops were brought to full detectable warning surface compliance within a single 11-week construction season, with zero service disruptions extending beyond the planned overnight maintenance windows. The completed project eliminated all DWS-related findings from the FHWA audit report and closed the associated items in the transit agency's ADA Transition Plan. IndyGo's ADA Coordinator received a stop-by-stop compliance documentation binder suitable for submission to FHWA as evidence of remediation and for use in any future DOT Title II compliance review. Product warranty documentation covering a 10-year manufacturer defect warranty on the cast-in-place panels and a 7-year warranty on the surface-applied epoxy panels was included in the project closeout package, along with contact information for warranty claims and installer certification records.
A 5-year maintenance inspection schedule was established as part of the project deliverables, specifying annual visual inspections of dome height and color contrast at all 18 stops, with quantitative measurements required every two years using the same calibrated instruments used during the installation verification. The schedule identifies threshold values that trigger proactive panel replacement before a stop falls out of compliance: dome height below 0.17 inches, luminance contrast below 75 percent (providing a 5-point buffer above the 70 percent compliance floor), or any visible panel delamination or cracking exceeding 2 inches in length. Maintaining this inspection cadence allows the transit agency to plan DWS replacements as a scheduled capital expense rather than an emergency remediation — a model consistent with best practices recommended by APTA (American Public Transportation Association) for ADA maintenance in transit environments.
