merge in turn 1548Uno Hoo! Your logic is faulty. If only a set number of vehicles can pbutt 'point...
"Uno Hoo!" wrote in message
merge in turn with physicsThat's right, but I think we should still try to spread the correct message as best we can. That way we at least have a chance of moving things in...
If you look at it mathematically this is all about road capacity. If you consider a road with standard size cars of 14 feet length which are travelling at the recommended 2 second interval, the traffic flow per minute at 60 mph is 27.8 and at 30 mph it is 25.9 cars-min.
If road is a dual carriageway and one lane becomes blocked the other lane can only end up with about 26 cars per minute however the traffic forms into one line before a queue starts to develop. As the speed drops in the open lane the road capacity drops. At 20 mph it is 23.7 cars-min, at 15 mph it is 22.75 cars-min, at 10 mph it is 20 carsmin and at 5 mph it is down to 15 cars-min.
If the cars in the open lane want to help cars in the closing lane merge they will need to provide slightly more than a 4 second gap if they want to maintain the overall minimum of a 2 second gap when everyone has moved into the single lane. To achieve this at 60 mph reduces capacity in the single lane to 14.4 cars-min. That buttumes we end up with a 14 foot long car sitting in a gap with a 2 second gap ahead and behind. For 30 mph the figure is 13.89 cars-min.
Thus if the flow of cars in the open lane is more than the above figures it is not possible to zip merge safely. The best option is for everyone to form into one smoothly flowing queue at the back without the need to merge at all as that will maintain a higher speed and greater road capacity.
Once speed drops below 10 mph the physical gap between cars travelling at a 2 second gap is less than 2 car lengths and even if the traffic jams closely together the merge is going to be difficult. At 5 mph the gap is down to 1 car length and zip merging is impossible unless the traffic in the open lane comes to a virtual halt.
merge in turn 1550Uno Hoo! I agree it is the method of choice and more efficient and less stressful provided that everybody knows the rule and obeys it. Sadly I don't think that UK drivers are...
merge in turn 1551Alistair J Murray" wrote in message Both of the above links are to articles by the same guy. The big difference between fluid dynamics and traffic flow is that molecules in a...
Longer vehicles such as large cars, vans, buses and lorries just make the situation worse.
The only advantages to using both lanes and zip merging near the obstruction is that the queue will be shorter in both lanes. This may mean that the queue doesn't backup to cause problems at another junction. Otherwise it isn't the panacea that most think it is in the NG.
Ian
