ADA Ramp Surveys in Petaluma, CA

Petaluma is one of the more demanding accessible-route settings in Sonoma County, and the city knows it: Petaluma publishes an ADA transition plan and runs a downtown ADA improvements program upgrading curb ramps, sidewalks, and related facilities across the downtown core. The reason is the building stock. Petaluma’s iron-front and brick commercial buildings along Petaluma Boulevard and Kentucky Street survived 1906 intact, which is why they are still standing and also why so many of them have entries raised above the sidewalk by a step, a cast-iron sill, or a shallow ramp added decades later at whatever slope the sidewalk allowed. Behind those facades the interior floor rarely matches the walk. The result is a downtown where the barrier is often the last 18 inches of the route, not the corner.

Measuring that last 18 inches takes more resolution than a level provides. The rules are unambiguous: 8.33 percent maximum ramp run, 2.083 percent cross slope under the 2010 ADA Standards and 2 percent under California Building Code Chapter 11B, 60-inch minimum landing length, and 1:10 flares on public curb ramps. We scan the sidewalk, the ramp or step, the threshold, and the interior floor as one connected surface, so change in level at the sill, landing length outside the door, and the cross slope of the approach all come from the same measured data. On a historic facade that also gives the architect the elevation geometry needed to design a compliant entry without guessing at the existing conditions.

Deliverables include slope and cross-slope exhibits with spot elevations, threshold and change-in-level callouts, ramp tables checked against Caltrans Standard Plans A88A and A88B for right-of-way work, and a DWG base map. We document; the CASp or architect certifies. See ADA compliance surveys and as-built surveys in Petaluma.