Mobile Vehicle Activated Signs

The parish council has purchased two mobile Vehicle Activated Signs (mVAS) to rotate around our approach roads.  These will monitor, and hopefully reduce, speeding through the village.  The data (records volumes and speeds, not individual registration plates) may be used by Thames Valley Police to more effectively target any speed enforcement activity or by Buckinghamshire Council when considering requests for speed mitigation measures.  

mVAS sites have been approved by Transport for Bucks in Vicarage Road, Cheddington Road, Marsworth Road and Westfield Road.  Units must rotate around these locations and can’t be permanently deployed at any one site. None of these 4 locations meet the necessary Department for Transport (DfT) criteria for a permanent VAS.

The output reports are discussed at full parish council meetings, which are open to the public.

More information relating to managing vehicle speeds can be found on the Buckinghamshire Council website here:

Please note that the data is recorded at the point that the vehicle comes into the line of sight for the mVAS. If the vehicle is travelling at over 35mph, the mVAS will flash a warning to the driver. Speed data is recorded for all vehicles whether or not the MVAS flashes. It is set to 35mph to allow for tolerances within both the vehicle and unit recording equipment etc. The unit can’t record any remedial action taken by the vehicle ie it won’t show if that vehicle slowed down once the flash was triggered.

A table of the latest results is shown below:

In the table the “Average Speed” is the mean average calculated for all vehicles. The ’85th Percentile Speed’ shows the speed at, or below, which 85% of vehicles were travelling. It is used by the DfT (and other organisations around the world) as a measure of the ‘actual’ speed of the road as compared to the speed limit. Unlike the mean it is not skewed by vehicles travelling below the limit.

Location85th percentile speedAverage speed
Cheddington Road37mph28.2mph
Marsworth Road28.3mph23.2mph
Vicarage Road30.1mph23.5mph
Westfield Road34.6mph29.38mph
Westfield Road/Warwick Road junction38.6mph31.28mph
mVAS data

The report for Westfield Road, following the relocation of the speed signs by Buckinghamshire Council is attached, along with all subsequent reports.

Please note the report includes the raw data as well as summaries and graphs and may be over 100 pages so be careful if you choose to print.

Also attached is the latest version of the mVAS policy and manual.