Meeting the intent of ADA in sidewalk cross-slope design

Recent work has indicated that prior research is insufficient to support the ADA Accessibility Guidelines' (ADAAG) 2% maximum cross-slope requirement for sidewalks. In addition, the present ADAAG are inflexible in that they do not consider deviations from this maximum for short sections of sidewalk, such as at driveway crossings, which can be of significant concern for state and local departments of transportation. Based upon these findings, a study was undertaken to evaluate the usable range of sidewalk cross-slopes by explicitly considering user perception and effort. Twenty subjects ranging widely in age and type of mobility aid participated in field surveys where they traversed different sidewalk sections varying in cross-slope, primary grade, length, width, and other characteristics. This paper illustrates the use of weighted-least-squares and ordered-probit regression models for analysis of disabled-user response to sidewalk characteristics. The results of these models permit estimation of maximum sidewalk cross-slope consistent with the intent and spirit of ADA. These are estimated to be 4%--where feasible-and 10%--where unfavorable construction conditions exist. Such results should prove useful for consideration of the final requirements of ADA on this topic. However, larger sample sizes and a stronger recognition of the population of interest are necessary before definitive, legislated maxima can be ascertained.