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

Objectives:

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.

Methodology:

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.

Themes:

Traffic calming, Horizontal deflection, Speed reduction,

Comments:

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

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