Cyclists submit over half of the videos received by the Police's Operation SNAP. A significant number of these videos concern 'close passes'. Guidance indicates that vehicles should, in urban situations, give cyclists at least 1.5 metres space, and, in situations where higher relative speeds are involved, they should ideally give at least a car's width of space.
It is not that easy to determine the closeness of passes from videos. This is especially the case when using the wide angle lenses employed in helmet cameras which appear to show objects to be further away than they really are.
This exercise is being undertaken to
The method used to accurately measure passing distances is described below.
All the videos have been converted to 'H264 - MPEG4 AVC format' - which ought to be playable on all phones and browsers.
A set of ten videos were obtained with a vehicle passing at a wide range of distances from a stationary 'cyclist'.
Below are a sample of five of these videos. You are invited to estimate whether any of the videos show passes that were closer than the recommended distance of 1.5 metres.
The videos are labelled with a character code (K, N, H, F and A) and links give access to rearward and forward facing cameras.
A separate page shows all 10 videos, together with the associated distances, however it is recommended that you first try to assess at least some of the five videos below before checking the results.
| Code | Cyclist's Rear Video Camera |
Cyclist's Front Video Camera |
|---|---|---|
| K | rear | forward |
| N | rear | forward |
| H | rear | forward |
| F | rear | forward |
| A | rear | forward |
A helmet camera was used to capture video footage. The camera is a Techalogic DC-1 Dual Lens Camera. It has a 140° horizonatal field of view front and back.
The camera was mounted on a tripod at a height of 1.75 metres, this is a average height for an adult cyclist. It was positioned 0.61 m (2 feet) horizontally from the curb which is a typical position adopted by cyclists to avoid drain covers and, some, potholes.
The car used was a VW Golf which has wing mirrors that extend 0.25 metres horizontally beyond the outside of the tyres.
In addition the half width of bike drop handlebars is about 0.25 metres.
A distance scale was marked on the road with graduations at 0.1 metre intervals. Zero on the scale was at the edge of the curb. If a car passed over the scale at the 3.0 metre mark (from the curb) then this represents a clearance between the outside of a bike's handlebars and the car's wing mirror of 3.0 (point on the scale passed by outside of tyre) minus 0.61 (distance of centre of bike from curb) minus 0.25 (half width of handlebars) minus 0.25 (distance of wing mirror outside tyre) = 3.0 - 1.11 = 1.89 metres.
A second video camera was set up looking across the road. It was positioned so that it could 'see' the whole of the distance scale. This camera could clearly record the point on the scale that the outside of the car's tyres passed.
The two video cameras mounted on tripods
click for full size image
A still showing the position of the car's tyres relative to the scale
The outside of the front tyre is 2.15 metres from the curb. This equates to passing the above 'cyclist' at a distance of 2.15 - 1.11 = 1.04 metres.
click for full size image
