Quantified risk assessment for road worker safety

Publication type:Report
Authors: C Fowler, S Clark, I Rillie, R Cuerden and L Smith
Document Reference: 514707
Publication Date: 21 June 2011 10:25
Assessment Level:
Peer Review Information:
Topics: No related topics

Executive Summary

Every year a number of road workers suffer fatal or life changing injuries as a consequence of their work. Other road workers suffer less serious injuries but the Highways Agency is committed to ensuring the safety of all road workers involved in maintaining the strategic road network. This requires prioritisation of investment and activity to ensure that safety of road workers is improved and that the benefits from these improvements can be measured and realised.

The highest risk process undertaken by road workers is traditionally viewed to be the deployment and removal of temporary traffic management (TTM). The MIRi Index has been developed from an in-depth understanding of the work processes involved with deploying TTM. The index applies to the deployment and retrieval of TTM associated with relaxation closures (excluding the longitudinal coning), which accident and incident data suggests is the highest risk activity undertaken by road workers.

The MIRi Index has been supplemented with a carriageway crossing value. This is based on an aggregated value of carriageway crossings and is not a precise value against which the Supply Chain should be assessed, but instead is designed to allow quantification of the substantial reductions in carriageway crossings that can be achieved by changes in working practices.

Examining the data from the MIRi Index demonstrates that the selection of the base method for deployment and retrieval of TTM is critical to achieving the lowest possible MIRi Index score. Elimination of carriageway crossings is an important part of reducing risk but without a sound base MIRi Index score it is likely that eliminating carriageway crossings will not drive down risk to road workers to a level that can be shown to be as low as reasonably practicable.

The analysis of the MIRi Index and carriageway crossing data was extended to two potential techniques that have been identified as approaches to reduce carriageway crossings. The TTM Sign Simplification (TTMSS) approach seeks to eliminate the 600 yard and 200 yard advance signing together with the Detail 'A' elements on the hard shoulder adjacent to the entry taper. This approach has the potential to reduce the MIRi Index by up to 22% and to decrease carriageway crossings by up to 52%.

If an aggregated value is calculated for likely decrease (based on best-estimate for the number of TM installations carried out using each method), TTMSS can achieve a national reduction in MIRi Index of 19% and a reduction in carriageway crossings of 46%. This is a substantial reduction which can be achieved with no additional equipment or requirements for road workers.

The second approach considered is that of offside signs relaxation (OSSR), where for nearside lane closures the offside signs are omitted. This achieves a similar reduction in MIRi Index (up to 28%) but reduces carriageway crossings by 100%. However, as this technique is only applicable to nearside lane closures its contribution towards achieving a substantial reduction in carriageway crossings is limited; if the two techniques are combined the indications are that the MIRi Index will decrease by an additional 2% to 21%, with carriageway crossings decreasing by an additional 9% to 55%.

These figures are based on a number of assumptions; it is recommended that these are validated from the Schedule of Road Works before these values are cited as evidence of likely benefit.