from Streetsblog.net by Utility Cycling
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Behind the Scenes — How Google’s Bike Maps Work
The push to get Google to incorporate bike directions into Google Maps has been going strong for quite some time now, but Google reports that adding such directions presented quite the engineering challenge. Google uses a few key features to develop the algorithm that generates a bike route, using the already-existing network of streets in their mapping system, which are summarized below.
1. Bike Trails – These show in dark green when you generate a Bike-There map. Google worked directly with the Rails-to-Trails Conservancy to find as many trails to incorporate as possible. The algorithm is weighted to send cyclists on trails as much as possible, as long as it doesn’t send them too far out of the way.
2. Bike Lanes – Google has information about dedicated bike lanes for 150 U.S. cities, which they used to build into the algorithm. Bike lanes appear on a Bike-There map in bright green, and they are also weighted as a priority in the algorithm.
3. Recommended Routes – These are routes from cities that have information about other good roads for cycling, which may not have an official bike lane. These roads are indicated by a dashed green line in the Bike-There map.
4. Uphill Slopes – In order to avoid hills (because, according to Google, nobody likes riding up hills… though I beg to differ…), Google developed a model that takes into account power (exerted by the cyclist), the slope of the road, wind-resistance, and speed. If the model shows that a given route requires an inordinate amount of exertion (aka too much power required) and will be too slow for time efficiency, Google will send you on an alternate route that avoids the climb. I could not find out what Google defines as “too slow” or “unreasonable degree of exertion”.
5. Downhill slopes – The model will also help cyclists avoid roads with too much downhill or descending, which can be tiring or disconcerting due to the unnecessary amount of braking required.
6. Busy roads – In order to keep cyclists off busy roads, the algorithm basically uses the inverse of the Drive-There algorithm in order to avoid arterials and freeways.
7. Intersections – Lastly, the algorithm avoids busy intersections with heavy traffic (car) and long waits.
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Review of Google’s Bike-There Features
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https://feedproxy.google.com/~r/utilitycyclingfeed/~3/Qd2prD_Cptc/oldId.20100503115833395
Biking in Baltimore