German Insurance Association Nr. 44 Prevention of overtaking accidents on rural roads Compact accident research Insurers Accident Research 3 Content Content Preliminary remarks 4 Introduction 5 Methodology 5 Accident occurrence 5 Effect of prohibiting overtaking and setting up a speed limit 6 Effect of bends, cambers and sight distances 7 Detailed analysis of the accident occurrence 9 Detailed analysis of overtaking behavior 10 Summary and recommendations 11 References 12 4 Compact accident research 44 | Prevention of overtaking accidents on rural roads Preliminary remarks Preliminary remarks 9% of the people killed on roads outside of built-up areas are the victims of overtaking accidents. These accidents are thus among the accidents with the most serious con- sequences on roads outside of built-up areas. The purpose of this now completed UDV research project was to ascertain the infrastructure-related, traffic-cont- rol and traffic-related factors influencing overtaking be- havior and overtaking accidents in order to be able to identify suitable measures to prevent these severe acci- dents. 500 sections of road in five different German federal sta- tes that were found to have the highest numbers of acci- dents served as the basis for this study. It was ascertai- ned where overtaking was prohibited (by means of road markings and signs) and what speed limits were impo- sed. On 100 of these sections of road, the sight distances at the accident locations were ascertained and included in the analysis of the accidents. In a detailed investigati- on, overtaking maneuvers were recorded on video and analyzed. This compact accident research report summarizes the findings of this study. You can obtain more detailed infor- mation from research report no. 24, entitled „Untersu- chung von Maßnahmen zur Prävention von Überholun- fällen auf einbahnigen Landstraßen“ (a study of measures designed to prevent overtaking accidents on single-car- riageway roads outside of built-up areas). You can down- load this report free of charge at www.udv.de. Insurers Accident Research 5 Introduction • Methodology • Accident occurrence horizontal and vertical plan, and the sight distances were ascertained, in order to analyze any effect they might Introduction have on the accident occurrence. Finally, in a total of 50 selected stretches of road with conspicuously high Around 75,000 accidents involving injury on roads out- numbers of accidents, a microscopic detailed analysis of side of built-up areas were reported to the police in 2012. overtaking behavior was carried out by means of video 2,151 people were killed in them, and a further 25,766 peo- observations. ple were seriously injured. Around 6% of these accidents and 9% of the fatalities occurred as a result of an overta- king maneuver. Overtaking accidents are thus particular- ly serious. The UDV therefore carried out a scientific investigation Accident occurrence to find out how, where and why overtaking accidents happen on single-carriageway roads outside of built-up The analysis of the accident occurrence consisted of a areas, and whether these accidents happen despite the nationwide analysis of the structure and consequences fact that overtaking is prohibited or in areas in which of overtaking accidents on roads outside of built-up are- overtaking is permitted [1]. Above all, the aim was also to as in 2009 and a detailed analysis of the accident oc- ascertain what can be done to prevent these accidents. currence in five federal states from 2007 to 2009. On 58,269 kilometers of single-carriageway roads outside of built-up areas, there were 85,345 accidents involving in- jury and serious property damage (category 1 to 4), inclu- ding around 6,200 overtaking accidents. Methodology The results can be summarized as follows: • Two-thirds of the overtaking accidents involving The basis of the study was a comprehensive analysis of injury were accidents in longitudinal traffic, a further sections of road outside of built-up areas where a dispro- 21% were turning-off accidents, and the remaining portionate number of overtaking accidents in five se- 10% were driving accidents (i.e. the driver lost control lected German federal states occurred. The road informa- of the vehicle). tion databases and accident databases were prepared • In half of the overtaking accidents the driver overtook and combined with this purpose in mind. Based on the despite the fact that there was oncoming traffic or the calculation of the accident indicators, 500 sections of traffic situation was unclear. 24% of the overtaking road were identified in the area covered by the study that accidents involving injury were frontal collisions, a were most affected by overtaking accidents. A survey ve- further 24% were side-on collisions with vehicles hicle was driven along these sections of road. The sec- traveling in the same direction, 14% were rear-end tions where overtaking was prohibited (by means of road collisions with the vehicle in front, and 11% were markings and signs) and speed limits were set up were accidents with vehicles turning into or crossing a road. ascertained. The overtaking accidents were assigned to • 76% of the people involved in the accidents who these different sections of road. In addition, for the 100 were partially responsible for the accident were sections of road with the most conspicuously high driving passenger cars, 16% were riding motorcycles, numbers of accidents, the axes were redesigned both in and 8% were driving trucks. 6 Compact accident research 44 | Prevention of overtaking accidents on rural roads Effect of prohibiting overtaking and setting up a speed limit The accidents that occurred in these sections were ana- lyzed, and the following results were obtained: Effect of prohibiting overtaking and • 74% of the overtaking accidents occurred in sections setting up a speed limit where overtaking was not prohibited. • 72% of the overtaking accidents occurred in sections with a speed limit of 100 km/h. As a result of further filtering, 500 sections of road out- • There was a lower risk of accidents occurring on side of built-up areas with a conspicuously high number stretches of road where overtaking was prohibited, of accidents and a total length of 2,235 kilometers were and the accidents were less serious (lower accident identified, on which a total of 1,557 overtaking accidents rate and accident cost rate). had occurred. These 500 stretches of road were driven in • There was an even lower risk of accidents and lower order to ascertain whether the accidents occurred on accident severity on stretches of road with speed sections where overtaking was prohibited. limits of less than 100 km/h (Figure 1). On average, overtaking was prohibited on 31% of the stretches of road driven. If overtaking was prohibited in both directions, this was generally indicated by a broken middle marking line (in 56% of cases) or by traffic signs (in 22% of cases). However, the combination of a broken middle marking line and the traffic sign, which is actually not permissible, was also frequently found (in 22% of cases). On around a third of the sections of road included in the study, there was a speed limit of less than 100 km/h. Risk and consequences of overtaking accidents on two-lane rural roads by speed limit Overtaking regulation Accident rate Accident cost rate Accident rate Accident cost rate [A/(106•veh•km)] [€/(1000•veh•km)] [U/(106•veh•km)] [€/(1000•veh•km)] Figure 1: Accident rate and accident cost rate 0.12 19.0 0.09 14.5 depending on over- taking regulations and speed limits 0.09 15.8 0.06 8.9 1) 0.10 12.0 0.07 9.4 0.07 13.9 0.07 9.7 1) partly removal slow vehicles Insurers Accident Research 7 Effect of bends, cambers and sight distances 100 s 90 80 97 n = 333 overtaking accidents included* 67 70 Bend to the right 60 Bend to the left 47 50 37 40 23 Figure 2: 25 28 Overtaking accidents Number of overtaking accident 30 22 by bend radius and 13 20 12 13 13 direction of bend 30 9 8 24 5 7 10 6 15 10 12 7 7 3 2 5 2 *It notovertaking accidents was possible to pinpoint of five the location 0 3 7 0 0 0 ∞ 20 ≤ > 1,800 201 – 400 401 – 600 601 – 800 801 – 1,000 1,001 – 1,201,201 – 1,4001,401 – 1,601,601 – 1,800 Bend radius [m] ted at over two-thirds (71%) of all cambers at which a cons- picuously high number of accidents occurred (Figure 3). Effect of bends, cambers and sight distances Figure 3 shows whether signs and what kind of road mar- kings were in place at typical accident locations on roads outside of built-up areas. Overtaking accidents also oc- The axes of the 100 stretches of road with the most cons- curred at intersections, and overtaking was not prohibi- picuously high numbers of accidents were redesigned ted in around half of these cases. for this detailed analysis. It was possible to pinpoint the locations of 333 overtaking accidents over a total road Around 70% of the overtaking accidents occurred in loca- length of 350 km. In addition, on the basis of the redesign tions where the sight distances were shorter than those the sight distances around the accident location were stipulated for safe overtaking in the guidelines for the ascertained. design of roads outside of built-up areas [2]. Moreover, 24% of these accident locations had shorter sight di- Around 71% of the accidents occurred within the sphere stances than the limit values stipulated in the guidelines of influence of bends. The tighter the bends, the more for the road markings [3].