Sunday, 20 November 2011

Counting bikes in Groningen

The moment that a cyclist is counted on a cycle-path in Groningen
In order to gather good statistics on cycling rates, there are many cycle counters in the Netherlands. All around the country, small grey boxes are chained to lamp-posts, a rubber lead from them stretching across the adjacent cycle path.

The boxes count cyclists who pass over the lead. They're left in place for a year, and the cycle count for the route is given as the number of times that the box has counted a bike, divided by 365. The counts produced are a true average over the whole year, not the result of counting on a sunny day in September just after the students have returned.

Any automated count like this has a margin of error. The boxes will always miss some cyclists. For instance, when cyclists pass side by side (even four abreast isn't all that uncommon with school-children), only one will be counted. When there is ice or snow, or perhaps due to leaves in Autumn, the box will also miss some bikes. However, the raw data is used because by consistently counting in the same way, figures are collected which can be compared from year to year. This is not a marketing exercise. There are no signs on the streets telling people how many have been counted.

This video has explanatory captions which are visible only if you view it on a computer. You won't get to see the point of the video on a mobile device.

The route shown in the photo and video is Zonnelaan in Groningen, where on average over 14000 cyclists pass each day. The busiest street which is currently counted in Groningen is Antonius Deusinglaan with over 19000 cyclists per day. These are large numbers for a city of just 190000.

Due to the high level of cycling all the way across the Netherlands, even small cities manage impressive counts. For instance, even though Assen's population is just 67000, an average of almost 9000 cycles per day pass through Nieuwe Huizen.

High counts are not in themselves a measure of success
Very high counts are often the result of a funneling effect where cyclists are forced to all go along the same route because of a lack of alternatives. Due to the cycle network in the Netherlands being designed as a very dense grid of high quality facilities it is usually possible to find a direct route which is not overly busy as a result of funneling. Zonnelaan also features in a later blog post showing how the local government has worked to reduce the number of people taking this route by making a faster parallel route known to students who made up much of the cycle traffic along this road.

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