The Access Chain Model

Accessibility is not a binary state (“accessible” vs. “inaccessible”). It is a sequence of events. We call this the Access Chain, a model originally developed by the Sensory Trust.

If any single link in this chain breaks, the visitor may be unable to complete their visit.

The Sequence

1. Planning

The journey begins before the visitor leaves home.

  • Failures: Missing information, PDF-only guides, vague language (“fully accessible”), hidden links.
  • Goal: Provide enough detail for a visitor to decide: “Yes, I can do this.”

2. Travel

Getting to the vicinity of the building.

  • Failures: No mention of closest accessible transit, no taxi drop-off info, inaccurate distances.
  • Goal: Detail the journey from public or private transport to the building’s boundary.

3. Arrival

Moving from the property boundary to the entrance.

  • Failures: Narrow paths, steep gradients, loose gravel, lack of seating.
  • Goal: Describe the surfaces and gradients leading to the doors.

4. Entry

Passing through the threshold.

  • Failures: Heavy manual doors, high thresholds, intercoms at unreachable heights, locked “accessible” side doors.
  • Goal: Document the door type, weight, and any assistance required.

5. Navigation

Moving within the building.

  • Failures: Broken lifts, narrow corridors, temporary displays blocking routes, lack of clear signage.
  • Goal: Provide clear path widths and lift dimensions.

6. Participation

Engaging with the building’s purpose (exhibits, service counters, programs).

  • Failures: High counters, inaccessible seating, lack of assistive listening, no tactile options.
  • Goal: Detail how services and programs are made accessible.

7. Facilities Use

Using essential services.

  • Failures: Inaccessible toilets, no quiet space, lack of water bowls for assistance dogs.
  • Goal: Detailed specifications of toilets, Changing Places, and seating.

8. Exit

Leaving the building safely, including in emergencies.

  • Failures: Emergency exits with stairs only, no evacuation plan for disabled visitors.
  • Goal: document the exit path and emergency procedures.

Maintenance Risks: Where the Chain Breaks

The Access Chain is most vulnerable to maintenance failure. A perfectly designed building can become inaccessible in minutes:

  • The Blocked Route: Storing boxes in corridors or placing temporary signs in the path.
  • The Broken Lift: Lifts out of service without a public alert or alternative plan.
  • The Locked Door: Staff locking the “alternate accessible entrance” for “security reasons.”
  • The Temporary Exhibit: New displays that don’t consider wheelchair turning circles or cane-detection.

A good access guide documents not just the architecture, but the operational commitment to keep the chain intact.