Variable-message signs for cyclists by right-turning trucks

| January 17, 2011

Traffic accidents involving cyclists and right-turning have severe consequences. Because of the tragic traffic accidents related to cyclists and right-turning trucks, the Municipality of Aarhus and COWI have made a project, where the aim was to find a solution, which can reduce the number of casualties by right-turning accidents.

Although it is the truck that must wait for the cyclist, initiatives to make cyclists more aware of the right-turning trucks have been developed. In Aarhus variable-massage signs have been placed at critical signalized intersections, and the signs light up and alert the cyclists, when a right-turning vehicle is in the right-turn lane.

At the selected intersections two variable-massage signs were placed. The first sign is placed at the stop line for the cyclists, and the second is placed at the beginning of the right-turn lane. Beside the two variable-massage sign, a passive sign informs the cyclists about potential danger by right-turning, large vehicles. The passive sign is placed about 100 m before the variable-massage sign located at the beginning of the right-turn lane, as the figure illustrates.

In order to evaluate the effects of the variable-massage signs, the behavior of the cyclists has been registered by use of a video camera and a roadside interview survey has been conducted. The recorded conflict situations between cyclists and right-turning motorists have been divided into three different categories:
• Close (to an accident) conflict: A situation where the cyclist is forced to slow down or stop and go around the vehicle. An accident may happen.
• Serious conflict: A situation where the cyclist is forced to change his/her course and go right or left around the vehicle.
• Minor conflict: A situation where the cyclist feels insecure and thus alters his/her course and goes right or left around the vehicle.

When looking at the cyclists’ behavior, more cyclists rotate their head after the establishment of the variable-message signs compared to the situation before. The number of cyclists, who did not orient themselves was halved. This may indicate that the variable-message signs have the desirable effect, since more cyclists are aware of the potential danger and looked to the left going into the intersection.
In the conflict situations fewer cyclists were registered as being involved in “Close (to an accident)” conflicts, and this number was nearly halved.

The roadside interview survey showed that 86% of the interviewed cyclists expressed that they would prefer to cycle through the intersection with variable-message signs and that the perceived safety is improved and that the signs result in a sufficient awareness of the right-turning trucks among cyclists. Besides that 40% of the interviewed cyclists believe that there will be fewer dangerous situations, while only 1% believes that there will be more.
The registration of the behavior of the cyclists and the statement expressed in the roadside interview survey indicate that the variable-message signs improve the conditions in order to avoid right-turning accidents.

The project will be followed the coming years to register if the accidents will increase or decrease.

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Category: Infrastructure, ITS and Signing

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