Accessibility

Preamble

GTFS and Netex define accessibility primarily in terms of binary access for wheelchair users: it's either on or off. Whilst it is the desire of the OTP developers to broaden the scope of accessibility the lack of data limits us to use this definition in the implementation and in this document.

Unknown data

Many agencies have the same problem: data on wheelchair-accessibility is, if it exists at all, patchy. If you only included trips and stops that are explicitly set to be wheelchair-accessible rather than unknown, it would be hard to get any result at all. For this reason OTP allows you to configure which sort of unknown information should be taken into account.

Configuration

If you want to allow trips and stops of unknown wheelchair-accessibility then add the following to router-config.json:

{
  "routingDefaults": {
    "wheelchairAccessibility": {
      "trip": {
        "onlyConsiderAccessible": false,
        "unknownCost": 600,
        "inaccessibleCost": 3600
      },
      "stop": {
        "onlyConsiderAccessible": false,
        "unknownCost": 600,
        "inaccessibleCost": 3600
      },
      "elevator": {
        "onlyConsiderAccessible": false
      },
      "inaccessibleStreetReluctance": 25,
      "maxSlope": 0.08333,
      "slopeExceededReluctance": 50,
      "stairsReluctance": 25
    }
  },
  "updaters": []
}

The parameters for stop, trip and elevator mean the following:

name		default
onlyConsiderAccessible	Whether to exclude unknown accessibility and inaccessible stops/trips/elevators in the search.	true
unknownCost	The cost to add if an entity has unknown wheelchair accessibility	600
inaccessibleCost	The cost to add if an entity is known to be inaccessible	3600

Note: Unless your accessibility data coverage is complete you will receive much better results by setting onlyConsiderAccessible=false, because otherwise you receive barely any results.

Other parameters are:

• inaccessibleStreetReluctance: if a street is marked as wheelchair-inaccessible this is the penalty that is applied for wheelchair users. This should be quite high so that those are only chosen as a very last resort. default: 25
• maxSlope: the maximum slope that a wheelchair user can use without incurring routing penalties ( leading to those ways being avoided). default: 0.083 (8.3 %)
• slopeExceededReluctance: how steep should the cost increase when you exceed the maximum slope. By default, every percent over the limit doubles the cost of the traversal, so if the regular cost is 100, being 1 percent over the limit will lead to a cost of 200, 2 percent over will lead to 400 and so on. If you want an even steeper increase then set a value higher than 1. If you want it shallower use a value between 0 and 1. To disable the penalty set a value below 0. default: 1
• stairsReluctance: how much should a wheelchair user avoid stairs. This should be quite high so that they are used only as a last resort. default: 25

Accessible transfers

By default OTP only pre-calculates transfers between stops for able-bodied walkers. If they have no obstacles wheelchair users can use them, too, but there won't be guaranteed to be one.

If you want OTP to also pre-generate wheelchair-accessible transfers use the following configuration in build-config.json:

{
  "transferRequests": [
    {
      "modes": "WALK"
    },
    {
      "modes": "WALK",
      "wheelchairAccessibility": {
        "enabled": true
      }
    }
  ]
}

This results in OTP calculating an accessible transfer if the default one is found to be inaccessible to wheelchair users.

Example

A full configuration example is available at /docs/examples