Sally Dutton
Senior Engineer
Traffic Management Division
Department for Transport
Zone 2/07
Great Minster House
76 Marsham Street
Mr Andrew Baker
London
By email
SW1P 4DR
Web Site: www.dft.gov.uk
Our Ref: RED 12/04/02
29 October 2009
Dear Mr Baker,
Tyre wear and speed cushions Thank you very much for your Freedom of Information request of 31 August about speed
cushions. I apologise for the delay in replying, and should inform you that your request
has been treated as routine correspondence rather than a Freedom of Information
request.
The Department for Transport acknowledges that concerns have been expressed over
accelerated wear occurring on vehicles which traverse road humps repeatedly. In order
to ascertain whether these concerns were justified, we commissioned the Transport
Research Laboratory (TRL) to study the impact of traffic calming on vehicles and their
occupants. The resulting report from the study, TRL Report 614 (Kennedy et al., 2004)
concluded that vehicles travelling over road humps at appropriate speeds should not
suffer damage, provided the humps conform to the Highways (Road Hump) Regulations
1999.
The results of the research showed no damage to any of the vehicles, despite repeated
passes at speeds of up to 40 mph. The research did not specifically look at frost damage
and speed cushions. TRL Report 614 is available to purchase from the TRL website at
www.trl.co.uk.
Local Transport Note (LTN) 1/07 does include some advice on maintenance. As well as
the advice in LTN 1/07, Traffic Advisory Leaflet 4/94 provides advice on speed cushions
and can be downloaded free from our website at
http://www.dft.gov.uk/adobepdf/165240/244921/244924/TAL_4-941.
Local authorities have a duty under section 41 of the Highways Act 1980 to maintain their
highways, which includes any traffic calming features. Although the Department does not
produce specific guidance on maintenance, we do endorse 'Well-maintained Highways', a
code of practice for highway maintenance published in 2005 by the Roads Liaison Group.
It is available at www.ukroadsliaisongroup.org/roads/well_maintained.htm.
If you have concerns about speed cushions in a specific location, then you should contact
the relevant local highway authority.
091028 Baker speed humps.doc
It is important not to lose sight of the primary purpose of traffic calming, which is to reduce
vehicle speeds in areas where inappropriate speed is a problem, particularly in built-up
areas where vulnerable road users are more likely to be present. Traffic calming plays an
important role in improving road safety and meeting the Government’s road casualty
reduction targets. Each 1 mph reduction in vehicle speed resulting from traffic calming
has been found to reduce accidents by around 5%.
I trust this information is helpful.
Yours sincerely,
Sally Dutton
091028 Baker speed humps.doc
