Guide to the ADA Standards

Aisle ramps that are part of a required accessible route can have handrails on at least one side or within the aisle width instead of on both sides as required for other types of ramps. (§505.2) 

Handrails on assembly area ramps can be discontinuous and lack extensions to allow access to seating and to permit crossovers within aisles. (§505.3, §505.10)

Other handrails specifications, including those for height, clearance, gripping surface, and cross section, apply.