Roads Should Be Self-Explanatory

12 May 2022 Infrastructure

In addition to vehicle technology and the human factor, a functional and efficient infrastructure is also of crucial importance for road safety, not least for young people. The priority here should be, through road construction and traffic regulation, to eliminate factors that could lead to accidents and also help to mitigate hazard zones in such a way that any consequences would be as minimal as possible in the event of an accident.

Accident statistics from numerous countries show that approximately two thirds of 18-24- year olds who lose their lives in road accidents do so on inter-urban roads. There are many reasons for this. Excessive speed and driving under the influence of alcohol and drugs play just as much of a role as overconfidence and not yet having a particularly well-developed ability to correctly anticipate the course of the road and any possible sharp bends and to adapt the driving style accordingly. A analysis of the data from the road safety screening developed by the Baden-Württemberg Ministry of Transport (a tool that is still the only one of its kind in Europe) paints an interesting picture with regard to the importance of infrastructure for accident statistics, especially when it comes to young drivers. The data analyzed for this report come from the years 2016 to 2020 and concern accident statistics in non-built-up areas without freeways, i.e. on federal, inter-urban, and district roads. According to this report, around 20 percent of the people at the wheel of a car who caused an accident on these roads in Baden-Württemberg were part of the 18 to 24 age group. By way of comparison, in the much larger 25-64 age group, the total was just under 60 percent.


If you break down the accident statistics for the given period, it can be seen, among other things, that young people at the wheel of a car were involved in accidents resulting from a loss of control of the vehicle about twice as often as 25 to 64-year-olds (28.6 compared to 14.5 percent). A breakdown by road type shows a significantly higher proportion of such driving accidents for young people (30.9 as compared to 14.9 percent), in particular for inter-urban and district roads. The reasons for this are obvious: inter-urban and district roads, which make up 22,167 kilometers of the road network in Baden-Württemberg (federal roads account for 4,202 kilometers) contain a higher proportion of roads with narrower lanes which therefore also have tighter curve radii. This means that inexperienced drivers in particular have more problems following the course of the road with their vehicle. Due to their greater importance in the road network and their subsequently higher traffic volume, federal roads are generally of a higher standard.
Young people were involved in accidents with a turning or crossing vehicle in non-built-up areas (excluding freeways) in 25.3 percent of cases (compared to 25 to 64-year-olds in 33.3 percent of cases). Accidents in parallel traffic with vehicles in the same or opposite direction were caused by young people in 26.4 percent of the cases (25 to 64 year olds in 27.5 percent of the cases). Inappropriate speed or breaking the speed limit was attributed from two and a half to five times as often to young people as a proportion as to 25 to 64 year olds, depending on the type of cause of the accident and road category. About one out of three accidents caused by young people took place during the night – for 25 to 64 year olds this was “only” one out of four accidents. The road category had no influence on the value. In a third of the accidents involving young people, the road was either wet or covered in dirt or by snow – for 25 to 64 year olds this was the case for 28 percent of the accidents. Here, too, the road category had no influence on the corresponding value.


Even though the data in question is confined to Baden-Württemberg, it is likely to be representative of comparable road accidents in many other countries around the world. It is not without reason, for example, that the EU Commission sees infrastructure as a key policy area for improving road safety. This does not just entail new construction projects, but also, above all, the targeted increase in the safety level of existing roads, as underpinned by EU Directive 2019/1936 of October 23, 2019 amending Directive 2008/96/EC on road infrastructure safety management. Among other things, factors such as the condition of the road surface, the predictability of the road’s layout, the ability to see the road clearly, the design of the sides of the road, road markings, the design of intersections and junctions, and the creation of opportunities for evasive maneuvers and overtaking are also of great importance.
In fact, in addition to the condition of the road surface, the ability to see the road ahead and distinguish individual lanes in different light and weather conditions is a key factor for road safety on inter-urban roads. Conventionally, road markings, road reflectors, roadside guide posts and direction signs placed in front of bends are used to guide the driver. The roadside area design of inter- urban roads plays an major role both in avoiding accidents and in reducing the consequences of accidents. It serves as an initial guide for the driver as to how the road will continue. At the same time, it creates expectations about the condition of the road ahead and thus has a direct influence on the choice of speed, for example. Discrepancies between the course and condition of the road that are suggested and the actual road must therefore be categorically avoided.


Planting trees on the side of the road is a controversial topic that is brought up again and again. When it comes to indicating the course of the road ahead, an avenue is almost unbeatable. However, trees by the side of the road, regardless of whether they are planted in a row, at the edge of a forest, or individually, pose a very high risk to road users in the event of a collision. In addition, they present obstacles to visibility. Wild animals can suddenly run out from behind trees or bushes onto the road, junctions may be seen too late, and the interplay between light and dark means that pedestrians and cyclists, as well as other vehicles that are unlit, only become visible at a much later point in time.
Obviously, cutting down countless trees along inter-urban roads is not possible for a variety of reasons. On the other hand, it makes no sense whatsoever that young trees are still being planted right next to inter-urban roads. Bushes and shrubs are another ecological and safety-sensitive option for road design. When they are present, vehicles are brought to a halt over a large area and relatively gently. Traffic barriers and crash cushions can offer possible solutions at specific points which are known to be potentially dangerous due to trees that cannot be relocated. When drivers lose control of their vehicles, traffic barriers help to keep them on the roadway and thus prevent them from colliding with the obstacles behind. The system’s energy absorption and shape all attempt to slow down impacting vehicles with as little stress as possible for the occupants, without allowing them to “bounce off” into oncoming traffic. Special protective measures must be taken for motorcyclists, lower rails, for example.


Another problem associated with accidents on inter-urban roads is that overtaking maneuvers can often end in head-on collisions or skidding off the roadway. Insufficient visibility, misjudging distances and speeds, and impatience are just some of the reasons for the often fatal decision to overtake. Especially on inter-urban roads which see more traffic from trucks, there are significant differences in speed between vehicles and many car drivers want to overtake as quickly as possible. Suitable options need to be created here. The optimal solution would be to widen inter-urban roads to four lanes, with structural separation of the roadways, as has been the practice in Sweden for years now. Road safety on inter-urban roads can also be increased by using overtaking lanes in sections in combination with prohibitions on overtaking and speed limits. However, the mere ordering of maximum permissible speeds does not lead to an increase in safety. The desired effect can only be achieved if road users also obey the rules. There must therefore be a risk that speeding will be identified and punished. In the Netherlands, there is a system in place involving designing the road in such a way that you automatically drive at the speed that is intended there. Intelligent road design can thus reduce the need to monitor the speed limit.
What is clear is that road safety costs money. Measures to improve the infrastructure are often particularly cost-intensive. However, reliable and safe infrastructure is also the backbone of a country's economy, as well as individual mobility and thus quality of life. Long-term planning and a safety-oriented use of funds can help to save money in the long run. If you don't plant the tree right next to the edge of the road today, you won't have to pay for an expensive traffic barrier in front of it tomorrow. If you renovate and freshly mark the road surface over a large area, this is more economical than constantly repairing damage that is penetrating deeper and deeper into the road structure. In the end, the goal must always be the self-explanatory road that mitigates accident consequences. In other words, the user should intuitively recognize the type of driving behavior and what speed is required of them based on the road design alone. It should be possible to identify dangerous spots. At the same time, the road should offer sufficient safety margins so that a driver can quickly regain control of their vehicle after a mistake and, if possible, no accident would occurs or the consequences of the accident would be less serious.