Belgium has opened a 'turbo traffic square' on the R4 around Ghent, reported VRT News. However, its construction and implementation has lead to confusion, including what a 'turbo traffic square' even is.
Viewed from the air, it looks strange. Unlike at a classic intersection, traffic that wants to go left has to make a large turn on a three-lane road and sometimes wait for traffic lights. It seems like a roundabout, but it isn't because it's not possible to drive in circles. In fact, one might initially question why the government chose to design an intersection like this.
"A first solution was to redesign and renovate the existing intersection, but then you still have traffic jams," explained Marijn Struyf of De Werkvennootschap, the organisation renovating the Ghent ring road on behalf of the Flanders government.
"A classic roundabout would have led to even longer traffic jams. That's why we have opted for a turbo traffic square that can handle up to 25% more traffic than the traffic that is already there today. It is a solution that works well in terms of traffic flow."
Turbo squares to handle traffic
Turbo squares are based on the design of turbo roundabouts. Before entering a turbo roundabout, drivers already know which lane to choose, instead of changing direction on the roundabout. That is also the case with a turbo square.
A turbo square is created where a normal turbo roundabout no longer functions because there is too much traffic. These intersections can include roads with two lanes or more. In theory, a turbo square can process 11,000 vehicles per hour, while an ordinary intersection can only handle 8,000 vehicles.
Moreover, there are fewer collisions on the turbo square because drivers have to choose their direction before entering. Further to this, the square itself ensures that drivers slow down, which has a positive effect on road safety compared to intersections with traffic lights.
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In order to realise the full benefits of a turbo square, it is necessary to provide clear signage for drivers at least 400 meters before arriving at the junction.
Dutch research firm TNO shows that drivers wait an average of 45 seconds less for a red light at a turbo square. But that requires enough detectors on the road to measure traffic. At the moment, Flanders doesn't apply Dutch standards, with four detectors per direction.
The possibility for confusion
The same Dutch study shows that people find navigating a turbo traffic circle complicated at first. But after drivers have passed through it a few times, they understand and appreciate the more efficient traffic flow. Yet there is a chance that one-time passers-by get lost or even drive the wrong way.
TNO advises "being cautious in applying this type of intersection shape and only considering its application if the traffic capacity for heavy crossing traffic flows really makes it necessary."
In addition, cyclists need separate paths and tunnels under the lanes for cars, which Ghent has implemented.
