ADA Ramp Surveys in Antioch, CA

Antioch’s Rivertown downtown is a 1850s grid that steps down toward the San Joaquin River, and that fall shapes every accessibility question in the district. Along West Second Street and the cross streets running to the waterfront and the marina, sidewalks carry the street grade, driveways and curb returns interrupt the walk constantly, and the storefronts sit at floor elevations set to sidewalk grades that were established generations ago. Raised entries and single-step thresholds are common, and the sidewalk panels themselves have been cut and patched around a long history of utility work. The City runs curb ramp installation as a recurring capital project, constructing concrete curb ramps in existing sidewalks at various locations along with sidewalk, curb, gutter, and pavement replacement, which is the pattern that makes closeout verification worth doing while the contractor is still mobilized.

The reason to measure rather than spot-check is that these conditions are compound. A ramp poured to a correct design slope can still tie into a gutter that runs the wrong way, or land at a sidewalk panel that has heaved, and the route fails at the seam even though the ramp is right. We build a surface over the whole condition, tied to survey control, so running slope is computed over the actual run, cross slope over the actual panel, and the gutter counter-slope and landing are evaluated as measured planes. Detectable warning placement, which is required on curb ramps in the public right of way under Title 24, is recorded with the same capture.

Beyond downtown, the newer commercial corridors and shopping centers generate accessible parking and path-of-travel work: stalls and access aisles within 1:48 in all directions, ramps at 1:12 maximum, landings at least 60 inches long. Deliverables are slope exhibits, colorized surface maps, spot elevations, and CAD. See also Antioch topographic surveys and Antioch 3D scanning.