#5minsbybike – a Look Behind the Scenes
Bike Citizens enhanced its routing algorithm to display which distances in a city can be covered by bike within #5minsbybike. Considering various factors and parameters the algorithm calculates which places can be reached within a given time from an arbitrary (freely selectable) spot in the city.
How exactly does #5minsbybike work?
Like for the routing of the Bike Citizens App the specifically developed algorithm is based upon open data from the Open Street Map (OSM). Within seconds the routing spider extends from its original position. It is not necessarily a perfectly circular growth, however: constraints like slopes and crossroads prevent cyclists from moving along with maximum speed. These are the most relevant criteria for irregular shapes of the spider:
- direct connections and uninterrupted sections of roads
- slopes and differences in height
Direct connections and bike paths preferred
Assuming solely long and straight connections you would of course get equally far no matter which direction you take. In fact roads and bike paths in cities – especially in cities that have grown over centuries – are crooked and differ substantially in length. What the algorithm does is assess longer street sections and bike paths with direct connections with a better rating than short sections connected to crossroads.
Turning left and junctions have a bad rating
Crossroads often cause waiting periods or at least slowing down. The #5minsbybike function prices a longer delay at big crossroads which consequently reduces the overall reach during the given time. Similarly, the algorithm considers turning left or right and calculates an additional waiting period depending on how many lanes to cross when turning left.
Ascents influence the overall reach
Of course you can not cover the same distance when riding up a hill, compared with going down. Depending on the incline the algorithm therefore adds a certain time factor uphill and subtracts time when going downhill. As a consequence the area to be covered may shrink or expand considerably.
The challenge while programming was that terrain model of the global SRTM data is not always very exact and the result of the mathematical model of the route calculation not always conforms to actual conditions. Friends and messengers with different needs have tested the 5 Minutes by Bike function in various settings: cycling with a bike trailer, on the fastest way across the city or comfortably on their daily route to work.
This is how the #5minsbybike algorithm looks like. Check it out:
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