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Last edited 20 May 2015

Improving the Safety of Single Carriageways in Northern Ireland

Dean Elder, University of Ulster, UK.

Road traffic collisions are both a social and economic cost. With growing population and rising traffic volumes, road safety improvements are becoming a major policy issue for authorities.

The single biggest cause of road deaths in Northern Ireland is excessive speed on rural single carriageway roads. However, the risk of collisions on rural roads can be significantly altered through road safety engineering measures. This study examines road traffic collisions on single carriageways, exploring the performance of wide single 2+1 (WS2+1) carriageways as an effective road safety engineering solution to Northern Ireland’s single carriageway network.

An in-depth critical analysis of authoritative literature provided contextualisation for this study. Quantitative analyses of bespoke secondary data sets were conducted which found that 90% of fatal collisions occurred on single carriageways. WS2+1 carriageways were the best performing scheme type with a 67% reduction in collision severity. WS2+1 carriageway configurations are a beneficial, cost effective engineering solution that reduces driver frustration and collisions on single carriageways.

A wider communication and education strategy is strongly recommended as well as reviewing the viability of providing physical separation in order to eliminate the risk of head-on collisions.


This dissertation was the Premier Award Winner, Masters Dissertation Award, CIOB International Innovation & Research Award, 2014.

The judges said, “A superbly presented and well-written dissertation that addresses a topical issue and mobilises rigorous statistical analysis with full use of available secondary data. The literature review is exemplary. It draws from current literature and weaves together a compelling argument. It is an excellent piece of work that could easily be used for policy development and infrastructure investment in improving road safety in Northern Ireland and globally.”

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