Rural Roads

Rural Roads

How Effective?

Effectiveness of Remedial Measures

  • In Ireland it was found that, as the quality of rural roads improves, the overall accident rate falls. However the likelihood of a fatal accident increases, up to a certain threshold, before it begins to fall. This more accurate modelling of accident rates leads to a situation where road quality improvements can result in an increase in the seriousness and the economic cost of accidents, with major implications for cost-benefit analysis of rural road improvement schemes (Laird & Harris, 2010).

  • A Danish synthesis evaluating bicycle paths found that the implementation of bicycle tracks[1] in rural areas were much more effective in reducing crashes and fatalities than those implemented in urban environments. When bicycle tracks were introduced along roads in rural areas a 62% reduction in crashes was observed, as well as an 80% decrease in fatalities. This could be due to the higher speed levels on rural roads, meaning that the physical segregation of cyclists and cars could lead to a significant reduction in the number of crashes and fatalities (OECD/International Transport Forum, 2013).

  • Use of combinations of signs, markings, and physical measures can achieve speed reductions and consequent reductions in accident frequencies (DfT, 2007). A large scale evaluation of the use of vehicle activated signs (VAS) indicated that at speed limit roundel signs, mean speeds of the traffic as a whole were reduced by between 1mph and 14mph, the higher reductions being where the speed limit had also been reduced by 10mph. The average reduction in mean speed where there had been no change in the speed limit was 4mph. The junction and bend warning signs reduced mean speeds by up to 7mph, and the safety camera repeater signs yielded a reduction of up to 4mph (Winnett & Wheeler, 2002).

  • Use of optical speed bars at five sites in the USA (known as transverse bar markings in the UK) showed significant reductions in mean speeds and speed variance at the downstream end of the optical speed bars at four of the five sites (Balde & Dissanayake, 2013).

  • Australian research showed that travel speeds are reduced following a speed limit reduction, with clear safety benefits (26.7% reduction in casualty crashes) consistent with a power model (Bhatnagar, Saffron, de Roos & Graham, 2010).

  • An increase in the number of speed cameras and red light cameras on rural roads in Australia was associated with a steady increase in speed compliance over 13 years. The baseline compliance rate was 60.6% and reached 70.3% in 2013. The percentage of drivers travelling more than 10km/h over the speed limit also reduced from 8.6% to 5% (Radalj & Sultana, 2014).

  • In Holland, similar decreases in speeding were found at both enforced roads and at the nearby comparison roads that were not subjected to a targeted speed enforcement project. The best estimate for the safety effect of the enforcement project is a reduction of 21% in both the number of injury accidents and the number of serious casualties. The enforcement was unobtrusive rather than high-profile or overt. Reductions in speeds at the nearby control sites were attributed to ‘spillover effects’, although it could reflect a more general trend (Goldenbeld & van Schagen, 2005).

  • German research found that speed enforcement had a very positive impact on accident frequency and severity. Three years after the implementation of the speed cameras accidents leading to serious injuries were on average reduced by 37.5%. Installation of passing lanes has been very successful, too. In a two-year period head on crashes were reduced to zero. At the locations with a pair of passing lanes the overtaking moved to the passing lane downstream of the no-overtaking zone. This improves traffic safety providing that the downstream passing lanes are long enough (Weber & Jahrig, 2010).

  • Norwegian research found that experience from other countries has shown that rural 2-minus-1-roads (where the number of driving lanes is reduced from two to one and the shoulders are widened – effectively creating a single track road with hard shoulders on either side) do not lead to the expected speed reductions. It also found that overtaking vehicles pass closer to cyclists because cyclists cycle further away from the edge of the road than on roads without extended shoulders. There is also confusion among road users as to what rules apply on 2-minus-1-roads (Erke & Sorensen, 2008).

  • Average speed enforcement has been found to reduce mean speed and the 85th percentile speed by a third. Research has found that KSIs reduce between 33% and 85% after the installation of average speed cameras. They are also perceived as being fairer by drivers, as they monitor behaviour over a longer period of time and not at a single moment in time which might be argued as being a poor reflection of overall driving behaviour. In turn this has meant that drivers have been more supportive of their introduction on rural roads (Soole, Watson & Fleiter, 2013).

Run-off crashes:

  • In Australia, the use of raised tactile edge lines has reduced lane departures (run-off accidents) by around 49% in New South Wales (Tziotis, Pyta, Mabbott & Mclean, 2010).

  • In Spain, a targeted programme of Sideway-force Coefficient Routine Investigation Machine (SCRIM) skid resistance measurement and friction enhancement was associated with significant accident reductions at intersection and curve run-off incidents (Pardillo-Mayora & Jurado-Pina, 2008).

  • SCRIM analyses in Spain have shown that during resurfacing, the effect on intersection and run-off incidents of improving pavement friction from a mean SCRIM value below 50 to a value above 60 was an average reduction of wet pavement crash rates of 68% (Pardillo-Mayora & Jurado-Pina, 2008).

  • The use of shoulder rumble strips was found to reduce the number of run-off crashes on rural roads in Idaho. After the installation of the rumble strips there was an overall reduction of 14% in run-off crashes. The rumble strips were most effective on roads with moderate horizontal curves, where a 29% reduction was found. They also led to a 22% reduction on roads with no horizontal curve, as well as an 8% reduction on roads with sharp horizontal curves. (Khan, Abdel-Rahim & Williams, 2015).Intersection/junction crashes:

  • The provision of lighting at rural intersections in Minnesota reduced the incidence of fatal accidents during the hours of darkness (Isebrands, Hallmark, Li, McDonald, Storm & Preston, 2010).

  • Wisconsin’s Department of Transport have found that transverse bar markings installed on the approaches to rural intersections can cause drivers to reduce speed earlier and to a greater extent. This can significantly reduce the numbers of those types of accidents most susceptible to correction by transverse bar markings, including rear-end collisions and frontal impact crashes (Wisconsin DoT Transport Synthesis Report, 2007).

  • In Australia, cost-effective measures at intersections include measures to reduce speed and speeding and the injury consequences. These include speed perception measures, roundabouts, traffic signals, grade separation, channelisation, signing to clarify priority, removal of sight distance obstructions, provision of medians, skid-resistant pavements and limited access from side roads and driveways (Corben et al., 2005).

Head-on crashes:

  • Head-on crashes are generally among the most severe of all vehicle crash types. This crash type occurs when one vehicle leaves its path and comes into the path of another oncoming vehicle. In some instances this type of crash results from a steering wheel overcorrection, e.g. a driver veers to the roadside, instinctively turns the steering wheel to return to the road and travels across the carriageway. Therefore, ways to treat this crash type include treatments in the centre of the road, but also at the side. The chance of over-steering will be increased if there is a drop off between the road and the roadside or shoulder (an 'edge drop'), making it more difficult to return to the roadway. Excessive drop offs should be avoided (iRAP, 2010).

  • In rural areas central hatching can be used with longitudinal rumble strips or pavement markers to alert drivers when they are leaving their lane, achieving a 10-25% reduction in crashes (iRAP, 2010).

  • Median barriers physically separate opposing traffic streams and help stop vehicles travelling into opposing traffic lanes. Research has shown that they can reduce head on collisions by up to 60% (iRAP, 2010). (iRAP, 2010).

  • A study carried out in the USA investigated the effectiveness of centreline rumble strips in reducing lane departure crashes (either head-on crashes or accidents involving a vehicle crossing into the wrong lane) on undivided rural roads. The two locations, Mendon-Killington and Sheldon, both saw a decrease in the number of crashes. In Mendon-Killington there were 189 crashes in the nine years prior to the installation of the rumble strips, with head-on crashes accounting for 48% of these. In the five years after the installation there were 77 crashes, 47% of which were head-on crashes. While the proportion of head-on-crashes remained fairly similar across both time conditions, the average head-on crash total decreased from 12.86 to 7.2 crashes per year, showing a 46% decrease in annual rates of head-on crashes and a 43% reduction in annual rates of overall crashes. In Sheldon, there were 65 crashes in the eight years prior to the installation of the rumble strips, 32% of which were head-on crashes. In the four years after the installation, there were 41 crashes, nine of which were head-on, showing a 10.3% decrease in head-on crashes. The average head on crash total per year decreased from 2.63 to 2.25, while the average overall crashes per year increased from 8.13 to 10.25 (Ellis, 2015).

Technology

  • Recently the European Commission approved the development and implementation of eCall technology and infrastructure required for the handling of e-calls. The system will allow for emergency calls to be generated either manually or automatically from a crashed vehicle immediately after a collision has occurred. A study carried out to measure the effectiveness of this in-built technology found that it would lead to a 50% rescue time improvement in rural areas, representing a net gain of approximately ten minutes in rural areas. While this system is still in its very early stages, its development could have a significant impact on the number of collisions leading to fatalities or serious injuries on rural roads (ETSC, 2013).

[1] Bicycle tracks: Reserved space specifically for cyclists along a road, this allows for physical separation from vehicles, parking lanes and pavements:

  • Date Added: 03 Apr 2012, 08:04 AM
  • Last Update: 30 Jan 2017, 12:45 PM