Tuesday 27 July 2010

How is ‘cycling in London’ measured by Transport for London?

I asked TfL for details of how they measure 'cycling in London'.

Although their press releases always claim that cycle counts are taken on 40 main routes in London, they were only able to supply the names of 29.

Here's what TfL has to say:

The counts are taken from automatic cycle counters which are placed under the road surface on the Transport for London Road Network (TLRN). This is designed to provide a robust sample of cycling on the TLRN. The counts are collected using automatic cycle detectors that provide permanent coverage for each location. These units use inductive loop technology to detect cycles and the count data is stored in a roadside cabinet before being downloaded to TfL’s computer systems.

We measure cycle samples on the following sites:

Stockwell Road, Streatham Hill, York Road, Clapham Road, Vauxhall Bridge, Blackfriars Bridge, Chiswick Bridge, Homerton High Street, Pound Street, Tooting Bec Road. East Hill, Upper Richmond Road, Finchley Road, Camden Road, Great West Road, Harlington Road East, Mile End Road, Woodford Avenue, Seven Sisters Road, High Road Tottenham, Kennington Lane, Pentonville Road, Tower Bridge Road, East India Dock Road, London Road, Brompton Road, Well Hall Road, New Cross Road, Twickenham Bridge .

What is not clear to me is how accurate sub-surface cycle counters are, the frequency of the counts, and whether or not there is any margin of error. That aside, I do not myself believe that measuring cycling on just 29 roads enables anyone to generalise about ‘cycling in London’ in the way that TfL does. The London Borough of Waltham Forest, which is just one London borough, has some 1,300 streets. No one seems very interested in taking regular, comprehensive counts, and Waltham Forest hasn’t published a cycle count since 2007.

My photo shows an Advanced Stop Line on New Cavendish Street, W1, occupied at red by a bus driver and a black cab driver. An everyday scene in London, city of a so-called cycling revolution.