The ADA/ABA Accessibility Guidelines only require one accessible route to all spaces that are required to be accessible.
206.2.4 Spaces and Elements. At least one accessible route shall connect accessible building or facility entrances with all accessible spaces and elements within the building or facility which are otherwise connected by a circulation path unless exempted by 206.2.3 Exceptions 1 through 7.
But it is important to remember that not all accessible routes are created equal.
Take for example, a multi-story shopping mall. A mall may have several sets of stairs, escalators at key locations and a few elevators centrally located to best serve individuals with disabilities and families with strollers.
It is not uncommon for some larger retailers to occupy two floor within a shopping mall. Monumental stairs are usually provided in a convenient location for customers to travel between the floors. When a stair is provided within an individual tenant space, it is necessary to also provide a means of vertical access. It is not acceptable to require a shopper to leave the store to find a an elevator in the common area. The following section is from the revised ADA/ABA Accessibility Guidelines:
206.3 Location. Accessible routes shall coincide with or be located in the same area as general circulation paths. Where circulation paths are interior, required accessible routes shall also be interior.
Advisory 206.3 Location. The accessible route must be in the same area as the general circulation path……Additionally, accessible vertical interior circulation must be in the same area as stairs and escalators, not isolated in the back of the facility.
The requirement for interior accessible routes should be interpretted to be the interior of the tenant space and not necessarily just within the interior of a shopping mall.