"PC Paul" wrote in message
Just do the maths. A mile of traffic travelling at 10 mph at one vehicle apart (1 second) contains 188 cars and at 2 vehicles apart contains 120 cars. A mile of road at 70 mph and 2 seconds apart contains 24 cars. The difference is the space wasted by the 2 second gap which is proportional to speed.
Every minute the cars in the 10 mph queue move forward 1-6th of a mile, which is 31 cars at 1 second spacing and 20 at 2 second spacing. Every minute the cars at 70 mph move forward 1 1-6 miles which is 28 cars. Volume of traffic and speed are different.
Incidentally, if the cars in the 10 mph queue are trying to keep the queue jumpers out and are at 1 second gaps, the overall length of the queue in that lane has reduced by more than a third compared to the 2 second gap alternative.
Interesting document, thanks for the link. I note that they reckon that merge in turn is only suitable for dual carriageways forming one lane, not multiple lanes and where the speed limit through the single lane is no more than 50 mph. They also consider it is only useful if the queue would otherwise stretch so far back as to affect another junction.
That item is about Mobile Lane Closures (MLC).
I haven't picked random figures out of the air. A typical car in the UK is about 14 feet long and that is what I have based my figures around. I haven't considered the effect of adding longer vehicles into the traffic flow as I admitted before. The distances apart I have used are based upon the 2 second rule from the Highway Code.
Ian
