BobFuck wrote:In number of deaths / car.km the roads limited to 90 (departmental ...) are much more dangerous than the highways, and the accidents are not mainly caused by excessive speeding compared to the limitation! .. .
Yes it's right.
Little reminder:
Speed is an aggravating factor on two main points:
1) The power believes in the square of the speed:
Recall that if the speed increases, the kinetic energy increases squared of this one either: Ec = ½ m × v2
By doubling the speed, the impact power increases by 4, therefore past a certain threshold, and those despite passive or active safety technologies, the laws of physics greatly reduce the chances of survival of the passengers.
2) Braking distances: direct consequence of point n ° 1, if the speed increases, the distance traveled per second increases in proportion to this, so the faster you drive and the more time it takes to stop; where the need to respect the safety distances to the letter.
To these there must be added the state of the driver: reflexes related to fatigue, alcohol, drugs, the degree of nervousness, age, sex etc ...
Now, speed alone does not explain all the problems, because it is often a question of multi-factorial accidents. (See above + weather conditions, traffic conditions etc ...)
For example, it is less dangerous to drive on a motorway at 130 km / h on a Sunday morning than to drive at 80 km / h on a Friday evening on a so-called "fluid" ring road.
But in any case, the speed
don't fix anything, hence the efforts to reduce it for years ...
On the motorway, three quarters of the journeys are on straight or almost straight lines allowing a clear vision favoring anticipation, this is not always the case on national roads, which tend to follow the landscape more.
In addition, the highways are closed (except the ramps) and fenced around the forests, which is not yet the case for RNs.
Overall, the highways are equipped with better infrastructure and more information ...
On the other hand, if we reduce the speed AND the number of vehicles, and sprinkle the whole with a program of prevention, deterrence and road repression as well as technologies that go well with it, we would arrive at a fairly good result. satisfactory.
"Engineering is sometimes about knowing when to stop" Charles De Gaulle.