7. Conclusions
Wheelchair users and the visually impaired face physical obstacles on city streets that inhibit their movement and place them in danger. Our review of the Broadway Curb Cut Survey, one of the most prominent data collection efforts to address this issue, underscores the costliness of producing data on the issue. To simply map out ADA compliance on a single New York City street required 40 volunteers and a year of time. Our work reviews this process and explores how new sensing technologies could expedite the process in future. Generating more data on the simple question of whether curb cuts are too steep, crumbling, or lack detectable warnings is crucial to drive progress on the issue - since without this information, agencies face no accountability to deliver their promise of better accessibility and DOT managers are un-informed about where investments are needed.
Our field work establishes the viability of using 3D sensing technologies to generate accessibility data. We defined a data schema based on the minimum required data points needed by key stakeholders in urban accessibility, and set data quality requirements based on stakeholder needs. The P40 LiDAR scanner produced better quality point cloud data, but the mass market Structure Sensor - currently retailing at $300 and representative of technology likely to be in the rear cameras of smartphones from 2019 - met all of our data quality requirements. Slope, width, and lip / bump measurements were successfully extracted from the Structure Sensor point clouds.
Having pressured the city to increase its attention to street accessibility through past lawsuits, disability advocacy groups can be expected to maintain pressure in future - especially given the continued extreme gap between ADA requirements and actual sidewalk ramp conditions in New York and other cities. 3D sensing combined with smartphone survey methods offers an opportunity to advocacy groups, and the city departments they aim to pressure, to build stronger operational awareness of accessibility conditions, and step up progress towards closing the compliance gap. To this end, we recommend creation of a smartphone app based on survey methodology but incorporating 3D scans.
The advantages of 3D sensing, observed in this work, could extend to other accessibility challenges beyond sidewalks. 3D scans of the urban built environment have credibility that simple text-based reporting may lack. For instance, a crowd-sourced effort sponsored by a disability non-profit might focus on entrance ramps to cinemas. Citizen engagement may be facilitated by smartphone capabilities whereas taking physical measurements would be deemed unusual behavior in public space. A user-generated 3D scan could be shared (through web methods such as SketchFab) with cinema management, providing objective evidence that ADA requirements, such as maximum ramp slope or minimum turning space in corridors, have been violated. Combining 3D scans with Geodatabase architecture can allow for powerful evidence to accumulate, helping to drive change on urban accessibility that would not otherwise be possible.