49 CFR Part 27 - Nondiscrimination on the Basis of Disability in Programs or Activities Receiving Federal Financial Assistance (with amendments issued through Aug. 2015)

(3) Pedestrian over-passes, under-passes and ramps. Pedestrian over-passes, under-passes and ramps, constructed with Federal financial assistance, shall be accessible to persons with a disability, including having gradients no steeper than 10 percent, unless:

(i) Alternate safe means are provided to enable mobility-limited persons to cross the roadway at that location; or

(ii) It would be infeasible for mobility-limited persons to reach the over-passes, under-passes or ramps because of unusual topographical or architectural obstacles unrelated to the federally assisted facility.