Little quantitative analysis has been conducted into how effective the various elements of TTM are. This may be attributed to the prescriptive nature of roadwork guidance and risk aversion (with regard to trying approaches different to that stipulated by the guidance).
The following statements are the few quantitative measures of effectiveness found during compilation of this synthesis:
Quantitative risk analysis of Temporary Traffic Management (TTM) operations has shown that simple changes to the layout can reduce the risk index score for road workers.
- Omitting the 200 and 600 yard advanced signs and the Detail ‘A’ element on the hard shoulder has the potential to reduce the risk index by up to 22 per cent and to decrease carriageway crossings by up to 52 per cent.
- Eliminating offside signs when setting out nearside lane closures has the potential to reduce the risk index by up to 28 per cent and reduce carriageway crossings by 100 per cent.
(C. Fowler et al., 2011)
Application of LED speed display and automated enforcement in Illinois resulted in significant speed reductions in work zones. Comparing before and during enforcement speeds at three separate work zone locations, the percentage of free-flowing vehicles exceeding the speed limit decreased from 93, 40 and 30 per cent to 45, 8 and 4 per cent respectively.
(P. Tobias, 2011)
Gaps in the research
An unpublished study for the Highways Agency found little research considering the overall effectiveness (as distinct from simply compliance) of time over distance (average speed) enforcement systems, particularly when used in roadworks.
(M. Brackstone, 2008)
An assessment of driver understanding of roadworks at a scheme level should be conducted in order to identify potential opportunities for rationalisation of signing. Currently only individual types or elements of signing are considered at any one time.
On-road trials of VSL technology in the UK should be conducted in order to identify whether this can be safely deployed. VSLs have the potential to offer many benefits to road users and road workers.
Existing studies predominantly cover road works on high speed roads. As more RTIs tend to occur on low speed urban roads, there remains scope to further investigate safety issues around road works in this environment.
The single most effective action that could improve road safety at roadworks is likely to be assessed education. Research into how this could be implemented (technically and financially) and the potential benefits would be valuable.
To promote research and innovation in the UK emphasis should be given towards the understanding that TSM Chapter 8 is a guidance document, and is not a ‘rule book’. Encouraging more innovation, backed up by robust research, should lead to improved safety for all road users.
- Date Added: 03 Apr 2012, 08:09 AM
- Last Update: 30 Jan 2017, 12:34 PM