Roads Must Be Forgiving of Mistakes

Jun 2017

Infrastructure

Vehicle technology and the human factor are the two central pillars of road safety. A properly functioning and efficient infrastructure is important, too. The challenge here is to implement road construction and traffic management measures designed to eliminate factors that contribute to accidents and to make hazardous sections of roads safer with the aim of mitigating as far as possible the severity of accidents. When it comes to infrastructural measures, factors such as speed monitoring at accident blackspots, rescue services and the maximum possible standardization of traffic regulations should not be forgotten.

Whether traveling in a vehicle or by foot, anyone who goes out on the roads to get from A to B wants to reach their destination safe and sound. The infrastructure plays a key role here. The variety of needs that road users have, the often limited financial resources available for planning, maintaining, building and upgrading roads, aspects concerning conservation and environmental protection as well as geographical, geological and climatic conditions all pose huge challenges for planners. At the same time, however, improvements in the field of intelligent transportation systems and the potential of variable lane usage open up whole new possibilities.

Infrastructure and traffic route planning is fundamentally possible only with a long-term approach. New technologies combined with the ever more rapid changes in our mobility behavior and the associated changes in our vehicles inevitably lead to problems. One example is the increasing use of bicycles in urban areas. In addition to increasing environmental awareness and the desire for exercise, this trend can be attributed above all to the fact that it is often simply quicker to travel by bicycle in urban areas than it is by car. The promotion of urban cycling is, therefore, in many respects a good thing. The Netherlands has for a long time been a pioneer in Europe when it comes to urban cycling and today can point to a solid cycle path network complete with the necessary accompanying legislation as the result of its efforts.

Potential for conflict between cyclists and motorists

The fact that expanding the cycling infrastructure in response to current trends sells well in many places has not gone unnoticed by local politicians in Germany. However, the lack of a big-picture concept combined with an overarching desire simply to build as many kilometers of cycle paths as possible for as little money as possible in as short a time as possible are frequently counterproductive to the aims of making cycling more attractive, encouraging a spirit of partnership and, ultimately, making our roads safer. Clear regulations stating the minimum requirements that cycle facilities are to meet and where such cycle facilities are to be situated ensure clarity among all stakeholders and, in turn, enhance safety. The physical separation of cyclists and motorists is not possible everywhere. At the very latest at crossroads and junctions, cyclists and motorists are forced to share the same space – with all the potential for conflict that this entails. The following aspects must be taken into account here:

  • Cycle lanes must be suficiently wide and also able to accommodate cargo bikes;
  • A safety distance must be maintained from parked vehicles to minimize the risk of cyclists colliding with car doors that suddenly open in front of them;
  • Road lanes must be wide enough to allow motor vehicles to overtake cyclists at a sufficient distance from the side of the vehicle;
  • The surface of cycle lanes must be suitable and that (i.e. no storm drains or cobbled curbstones).

If it is impossible to ensure the safety of cyclists with dedicated cycle lanes, a speed limit commensurate with the volume of road and bicycle traffic may have to be introduced. Often, however, problems can be solved in other ways that do not necessarily involve integrating bicycle traffic with motor vehicles along main roads. A suitable cycling infrastructure on parallel side roads where cyclists enjoy clearly managed priority can improve safety for all road users. At the same time, systematically punishing violations will ensure that the cycle path infrastructure not only remains unobstructed by parking offenders and delivery vans/trucks, but is also used properly by cyclists themselves.

Positive experiences with barries an 2+1 roads

Differences when it comes to accelerating ability, maneuverability and speed are critical to safety not only in mixed traffic situations where motor vehicles, cyclists and pedestrians share the same space, but also in situations where the only road users are motorists. This is especially the case on country roads where the speed of vehicles can be high but it is either impossible or nearly impossible to overtake safely. Just how dangerous this can be is demonstrated by an example from Portugal, where – among other places – one particular section of the IC 2 linking Lisbon and Porto was a notorious accident blackspot. In 10 years, 77 people died on a section of road just three kilometers in length. In response, an action plan was devised at the end of 2015 aimed at improving the signage and widening the lanes. The central measure of this plan was to construct a protective concrete barrier in the middle between the two lanes. The result? While eight accidents with two fatalities, two seriously injured persons and three persons with minor injuries were recorded along this stretch of road in the first half of 2015, in the same period of 2016 no one died. Ten accidents were recorded, with seven people suffering “only” minor injuries.

Barriers have helped to make roads safer elsewhere, too, including the USA – in Missouri, for example. Between 1996 and 2004, around 380 people were killed in collisions with oncoming traffic on just three highways; 2,256 people were injured. In response, work began on constructing reinforced steel cable barriers in the middle of these highways. These measures proved highly successful: According to the Missouri Department of Transportation, the number of people killed in accidents involving collisions with oncoming traffic fell from an average of 18 to 24 per year to 1.

The ideal way to prevent accidents involving collisions with oncoming traffic would be to construct all roads in the form of a four-lane divided highway with both sides separated by a physical structure, but this would of course be impossible for a number of obvious reasons – conservation, the amount of space required, cost and the actual need for such a measure. But there is no doubt that for busy roads – especially those frequently used by commercial vehicles – this solution would offer the greatest potential for improving safety simply because it would make overtaking virtually risk-free.

The concept of 2+1 roads, which was developed in Sweden in the early 1990s, has proved successful in situations where it is either undesirable or impossible to upgrade to a four-lane divided highway, but safe overtaking opportunities are to be ensured nonetheless. This road design consists of two lanes in one direction and one lane in the other, alternating every few kilometers. The conventional 1+1-lane configuration in the intermediate sections varies in length from an immediate transition to a stretch covering several kilometers over which drivers are forbidden from overtaking.

Experience of roads constructed in this way has shown that the number and severity of accidents are reduced and drivers are more likely to observe the ban on overtaking in the intermediate sections. 2+1 roads are popular not only in Sweden, but also in the USA, Australia, New Zealand and Germany. In Sweden, the two sides of the road are often additionally separated by steel cable barriers. Although this road design reduces the risk of front-end collisions, concerns raised about the potentially higher risk of injury to motorcyclists have prevented this system from being introduced in many other countries.

A modified form of 2+1 roads is also ideal on sections of road that are heavily used by commuter traffic in the morning in one direction and, in the evening, in the other direction. By ensuring that the middle lane is utilized according to demand, the flow of traffic can be optimized with minimal land usage. Either electronic display systems or mobile separators are used to indicate the direction of traffic. The most prominent example of the use of mobile lane separators is the Golden Gate Bridge between San Francisco and Marin County. Here, the six lanes can be divided up into a 4+2, 3+3 or 2+4 configuration, depending on requirements. Since the separators are moved automatically, lane usage can be configured very quickly, traffic guidance is clear and safety is very high. The system is ideal not only for bridges, but also for longer stretches of road.

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