FAQs

How is an a11y-Score calculated?

The a11y-Score is based on open data from OpenStreetMap (OSM for short) — a world map that volunteers create and keep up to date, much like Wikipedia. Many of them also note down how accessible a place is: Is there a step at the entrance? Is there an accessible toilet? Are there tactile guidance strips for blind people?

Three questions about every place

For every place on the map, we look at three things:

  • Where is it? — country, region, city, neighbourhood. This tells us which region's score the place counts towards.
  • What kind of place is it? — a kindergarten, a restaurant, a hospital, a train station … Every place belongs to exactly one category.
  • What do we know about its accessibility? — for example about mobility, toilets, vision or hearing. A place can count towards several of these topics at once.

Not just yes or no

Accessibility is rarely all or nothing, so we work with levels instead of a simple yes or no. Each level gets a value between 0 and 1—the more it helps people in everyday life, the higher the value. For getting through an entrance in a wheelchair, for example:

  • fully wheelchair accessible: 1.0
  • partially wheelchair accessible: 0.5
  • not wheelchair accessible: 0

Some features have even finer levels: tactile paving that covers only part of a route counts 0.25, a single orientation aid counts 0.1—and tactile paving that leads blind people the wrong way counts 0.

Some things matter more than others

Not every criterion is equally important. Our team decides how much each criterion counts compared to the others in the same topic. For mobility, for example, the entrance might make up 80 % of the value and the accessible toilet 20 %: Because you have to get through the door on every visit, but you don't always need the toilet. We can adjust these weightings over time as we learn more.

Unknown doesn't mean bad

For most places, only some details have been recorded so far. OpenStreetMap grows with every contribution from volunteers. That's why missing information never pulls a score up or down: each place is rated only on what we actually know about it.

So that you can judge how reliable a number is, every chart also shows how many places it is based on—for example “12 of 30 places have data for this topic”.

From a single place to a whole region

The score is built up step by step:

  1. Each place gets a value for each topic that sums up everything known about it, weighted as described above.
  2. For each category—say, all restaurants in a region—we take the average of all places that have data on the topic.
  3. Broader categories that group several smaller ones combine their values. Categories with more places count for more.
  4. Together, this makes up the score for the whole region, including its cities and districts. Besides the average, every chart also shows how widely the values spread (median and quartiles)—so you can see whether places are similarly accessible or whether some do much better or worse than others.

The score of a single place

In the place lists, every place also gets its own value from 0 to 100 points for the topic you have selected, calculated the same way as for a region, just for this one place.

Further information