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Roundabouts were the magic bullet against dangerous intersections, but now they’re becoming increasingly clogged. New solution: the traffic light.
Many regions in Switzerland know the dilemma: the population is growing, the economy is booming – but traffic is increasing as a result. Traffic jams in the morning and in the evening are programmed. Sursee in Lucerne is also affected. That is why the canton is now resorting to a means that makes people sit up and take notice: Various traffic roundabouts are to be dismantled and replaced by intelligent traffic lights.
Roundabouts are dismantled
Sursee is an example of why certain roundabouts have had their day. The community has grown at an above-average rate in recent years – with corresponding effects on settlement development, says cantonal engineer Gregor Schwegler. «The development of Sursee could not be foreseen exactly. That’s why the roundabouts are designed for a direction that is no longer quite correct today.”
Now a total of seven roundabouts are to be dismantled and replaced by the latest generation of traffic lights. Cost point: up to 60 million Swiss francs. These modern traffic light systems are controlled by algorithms.
The green phases are therefore not permanently programmed, but the system calculates flexibly how traffic can be handled most efficiently, says Schwegler. “It can look different in the evening than in the morning.” Depending on the traffic load, the traffic light changes phases. Specifically, this can mean that buses are preferred at certain times.
Lucerne has tested intelligent traffic lights
With a pilot project, the city of Lucerne recently showed that intelligent traffic signal systems can reduce waiting times for all road users. Such a system was installed on Tribschenstrasse. Sensors built into the road surface measure how many cars are currently on the road, and cameras monitor what is happening at the intersection.
The system registers when a bus is approaching or a pedestrian presses the red button at the traffic light. An algorithm then calculates the best course for the traffic flow. The pilot test is a success, according to the city. The waiting time has been reduced by a third. Experts also confirm the potential of intelligent traffic light systems. However, they warn: In order to improve the flow of traffic in an urban area or community, it takes more than one such system.
The federal government is also aware of the problem
The Federal Roads Office Astra is also interested in such solutions. Because the traffic gets stuck in the roundabouts, it sometimes backs up onto the nearby freeways. A problem that does not only exist in the canton of Lucerne, says Astra director Jürg Röthlisberger. “We know this problem with practically all motorway connections in the Mittelland in the evening and in larger agglomerations also in the morning.” The entrances and exits are affected.
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This traffic light system on Tribschenstrasse in Lucerne is controlled by an algorithm. Experts warn, however, that more than one intersection would have to be upgraded to ensure good traffic flow.
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For its part, the Astra is also examining ways in which congestion could be reduced. Various motorway exits are to be temporarily extended to the emergency lane and at peak times, a speed limit of 80 will soon apply on certain sections. The no longer functioning roundabouts occupy all levels of government: municipality, canton and federal government.