Thought of the Day - Traffic Management Idea

Last week i was sitting waiting in a traffic jam caused by road works and it occurred to me that traffic management is not run in the most efficient way.

If you consider the bottleneck in the process to be the physical bottleneck in the road and the number of vehicles passing as throughput, then it is clear that the bottleneck is grossly underutilised. As the traffic is running in opposite directions, it is clear that the bottleneck can never be fully exploited as you must wait for the last car in one direction before you can move in the opposite direction. However i think there are still significant improvements that could be made.

Firstly as soon as the last car clears the obstruction in one direction the next car should be moving in the opposite direction. Secondly the speed of the cars should be maximized past the obstruction to increase throughput. Finally the time taken for the cars to move off when the light goes green should be minimised.


So what might my traffic management system look like? I would set the lights back from the obstruction by the same length as the obstruction and have the lights change in the reverse direction based on when the last car leaves in the forward direction. This would allow the cars moving in the reverse direction to move off and get up to speed before the obstruction maximising throughput and minimising wasted time. This eliminates the lag in the system for the cars to move off, it also maximises speed through the obstruction meaning the bottleneck is maximally exploited.

There are 3 issues i can see with this system:
The first is if you get a boy racer at the start of the second set of traffic who screams past the lights and then has to jam on the brakes to avoid the oncoming traffic. This would disrupt the traffic behind and impair the throughput.
The second is if you had a very slow vehicle (crane, lorry or little old lady) they would act as a further bottleneck that would reduce the throughput. Unfortunately almost every traffic management system would retain this problem and by giving the vehicle time to accelerate before the obstruction the problem is minimised.
The final problem is that you cannot always see the full length of the obstruction, in this instance if there was a very slow vehicle passing the obstruction the two traffic flows could meet in the middle and come to a stalemate causing chaos. Unfortunately it is not possible to have good visibility on all roadworks so this may limit the locations where this system could be applied. It would also be possible to have an 'emergency stop' sign just prior to the obstruction to prevent this from happening if all of the traffic had not cleared the obstruction.

All of the above issues could be somewhat mitigated through public eduction either via signs or media sources and completely removed if you introduced two convoy vehicles to pace and control the traffic. While the latter option would greatly increase the cost of traffic management it could be used in high profile or high volume situations where throughput was critical.


While i'm sure every motorist would love spending less time in traffic jams and technically they are the end customer. In reality they don't control the cheque books and the cost of the additional equipment might discourage companies from using it. After all the because the motorists aren't paying, best case is that the company gets less complaints. But as with the Heroes Vs Planners debate they are unlikely to get positive feedback, there will still be a delay and the motorist won't know how bad the delay could have been if the system was not used.