Traffic calming – An assessment of selected on-road chicane schemes

  • Published: TRL, 1998
  • Authors: I.A. Sayer, D.I. Parry and J.K. Barker
  • Date Added: 05 Feb 2013
  • Last Update: 25 Oct 2016
  • Format: html


To draw together and study all the available data concerning the design and effectiveness of chicanes installed on local highway authority and trunk roads over the past decade.


Data collected from 134 authorities and 49 chicane schemes representing the 7 most common types. Each scheme included between 1 and 10 chicanes, and in all 142 chicanes were studied. The schemes were analysed for vehicle speeds, traffic flows, RTIs, geometric design signing and costs.

Key Findings:

  • In 1995 60 per cent of all RTI casualties occurred in built up areas and approximately a third of these were vulnerable (pedestrian and cyclist) road users.

  • Various types of horizontal deflections have been used in calming schemes to reduce traffic speed.

  • Chicanes installed in a large number of schemes on local and trunk roads, resulted in average speed reductions for mean and 85th percentile speeds were reduced of 12 mph at the chicanes.

  • Between chicanes, this reduction dropped to 7 mph. Two way chicanes appeared to achieve slightly smaller speed reductions that one way versions (5-7 mph higher).

  • Of the 17 schemes where before and after RTI data was available, an overall reduction in RTI frequency of 54 per cent (41.2 -19.0 RTIs per annum) was seen.


Traffic calming, Horizontal deflection, Speed reduction,


Another study of non physical measures by reviewing data from a reasonable number of schemes around the UK.