A reader proposes to assign a different speed to each of the three channels of the device. Risky, responds the State
“It wasn’t that long ago that the bypass was two-lane and 110 km / h, and it worked. Why did we switch to three lanes and 90 km / h? Instead of considering four lanes at 70 km / h, would it not be possible to try an experiment with right lane at 90, central lane at 110 and left lane at 130 and closed to trucks? »(Christian Mourguiat, in Bordeaux). To respond, we asked the various government services that manage traffic in Gironde. These recall that the passage to 90 on the ring road – as elsewhere in France – responded to an imperative of safety, reduction of noise pollution and also served to increase the “capacity” of the ring road: the reduction in speed makes also reduce the inter-distances between vehicles, do not increase the flow.
And why can’t we assign a different speed for each of the lanes? The shear effects should be too great between vehicles entering or exiting lanes, especially if they are traveling at varying speeds. In short, the risk of accidents would be too great.