Traffic calming – Speed Cushion Schemes

  • Published: TRL, 1998
  • Authors: R.E. Layfield and D.I. Parry
  • Date Added: 05 Feb 2013
  • Last Update: 25 Oct 2016
  • Format: html


To carry out an assessment of speed cushion design and effectiveness.


To review and assess 34 local highway authority traffic calming schemes using speed cushions. The study assesses the effect of cushions on vehicle speeds, traffic flows, RTIs, driver behaviours and passenger discomfort.

Key Findings:

  • The most effective forms of traffic calming usually involve some degree of vertical deflection.

  • Road humps have been proven to be highly effective at reducing vehicle speeds but cause driver/passenger discomfort, particularly in larger vehicles.

  • Speed cushions are effective at reducing speed, but not quite as effective as road humps.

  • While a comprehensive RTI survey was not undertaken before and after the traffic calming schemes were introduced, it is estimated from other studies that the reductions in speeds and flows is likely to achieve injury RTI savings of approximately 60 per cent.


Traffic calming, Speed cushions, Effectiveness.


An effectiveness study focussed on one particular calming measure. While not as effective as humps, cushions offer the benefit of not impairing the emergency services or affecting public transport passengers.