Good signals – for safety’s sake

| December 20, 2011

The City of Copenhagen has high ambitions when it comes to cycling: The goal is that by 2015, 50% of all transportation to and from place of work or education will be conducted on bike. In addition, it is to be safe and secure to cycle in the city. Thus, the number of seriously injured cyclists is to be reduced by 50% in the period 2007-2015.

By Claus Rosenkilde and Anne Eriksson, Traffic Department, City of Copenhagen

The city works systematically to improve the safety on our streets, particularly at intersections. Two-thirds of all accidents registered by the police in Copenhagen happen at intersections. Therefore, better traffic safety at intersections is one of our areas of priority in our action plan for traffic safety.

One of Copenhagen’s most busy intersections is located by the lakes: here, Nørre Søgade & Vester Søgade meet Gyldenløvesgade. On a weekday, about 100,000 vehicles and 50,000 bicycles pass through this intersection, and many pedestrians who walk or run along the lakes also pass through it. The intersection connects several of the large radial roads leading into the city centre and is characterised by right- and left-turning car traffic.

For many years, this intersection was the most dangerous in Copenhagen. In 2006, it was redesigned at a cost of approximately six million DKK in order to improve the level of safety. Prior to the reconstruction there was an average of 5.3 serious injuries per year. Now, this number has decreased to 3.4 per year. For the cyclists, the number of serious injuries has been cut in half. Prior to the reconstruction there were 3.5 serious injuries on average involving cyclists; a number that has now been reduced to 1.8.

We cannot say that it is now completely safe to pass through this intersection. But we have halved the risk that cyclists will get hurt crossing it. At the same time, the reconstruction has meant an improvement for the other road users as well, and that must be said to be a success.

Prior to reconstruction, the three most dangerous situations while crossing the intersection were:

  • Left-turning cars from Gyldenløvesgade to Nørre Søgade who ran into oncoming cars or bikes going straight.
  • Right-turning cars from Gyldenløvesgade to Nørre Søgade who ran into oncoming cyclists going straight (the so-called right-turn accidents).
  • Left-turning cars from Nørre Søgade to Gyldenløvesgade who ran into oncoming cars, cyclists, and pedestrians.

There were many things to be considered when redesigning the intersection. It had to be safe but also had to have room for the large traffic flows without turning the fine parks around the lakes into a freeway-style interchange. So the reconstruction combines a number of different solutions: turn arrows for left and right turns, forbidden turns, and a “prison-island” solution. In case this sounds like a catalogue from the Prison and Probation Service, here follows a short explanation:

Turn arrows: This is when a turning traffic flow has its own signal, i.e., red/yellow/green arrow. The right-turning cars from Gyldenløvesgade to Nørre Søgade have their own signal, so now they do not have a green light at the same time as the cyclists going straight.

Gyldenløvesgade drejepil

At their own green light, cyclists cross the lane for right-turning cars stopping at the red light.

Forbidden turns: Cars can no longer turn left to and from Vester Søgade. The left-turning traffic did not result in many accidents, but the solution was chosen in order to best direct the overall traffic in the intersection.

Prison-island solution: When cyclists are going straight ahead from Nørre Søgade to Vester Søgade, they first have to cross a car lane where the right-turning cars are stopping at a red light. Then the cyclists come to an “island” where they await the green light for the straight through traffic (both cars and bikes).

Gyldenløvesgade fangeøen

From the prison island, cyclists safely proceed straight ahead while the car can turn right at its own green light without risk of hitting the cyclists.

The intersection has now been adapted to match the traffic flows as best as possible and to prevent the conflicts the previous design caused, and the traffic lights have been set specifically for traffic in this intersection. Thus, here it has been great to design the intersection with good signals – for safety’s sake.

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Category: ITS and Signing, Newsletter 5, Safety

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