This work supports the road safety strategy and complements the speed policy review.
This study is to investigate further how best to manage speed on the rural, non-motorway road network and to build on outputs from current and recent trials of rural safety measures and other research on speed and the application of speed-accident results. This will bring together existing knowledge, report and make recommendations about speed accident relationships on rural single carriageway roads, and carry out an appraisal and development of the 'self-explaining' roads concept. It will also develop further the hypotheses and findings of the EU MASTER project applicable to rural road speed management.
The main results of this project are as follows:
- Accident frequency in all categories increased rapidly with mean speed
- All accident frequency increased with speed to the power of approximately 2.5 times - thus indicating that a 10% increase in mean speed results in a 26% increase in the frequency of all injury accidents.
- The relationship between accident frequency and traffic flow and the link section length mirrored that typically found in other similar studies.
- Accident frequency varied between the four 'Road Quality' Groups defined in the report. Group 1 being lowest quality and group 4 the highest quality rural road. It was highest on the Group 1 roads, and about half, a third and a quarter of this level on roads in Groups 2, 3 and 4 respectively.
- Two additional measures were found to influence the frequency of All injury accidents. These were the density of sharp bends (those with a chevron and/or bend warning sign) and the density of minor crossroad junctions. These increased accidents by 13% and 33% respectively for each additional bend/crossroad per kilometre.
- The effect of mean speed was found to be particularly large (power of about 5) for the junction accidents.
- No other measures of speed were found to influence accident frequency as strongly as, or in addition to, mean speed.
- The percentage reduction in accident frequency for a 1mile/h reduction in mean speed implied by the 'All accidents' relationship depended on the mean speed. It ranged from 9% at a mean speed of 27 miles/h to 4% at a mean speed of 60 miles/h.
- The effect of speed on fatal and serious accidents was greater than its effect on All accidents taken together, though the difference was not statistically significant. A 10% increase in mean speed would be expected to result in a 30% increase in the frequency of fatal/serious accidents.
This work will support the road safety strategy and complement the speed policy review.
No results directly relevant to this theme. However, please note that some findings relevant to the project's key theme (Safety and Security) are generically applicable.
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No policy implications directly relevant to this theme. However, please note that some policy implications relevant to the project's key theme (Safety and Security) are generically applicable.
No results directly relevant to this theme. However, please note that some findings relevant to the project'