AdamW said:
1) There are many people in this country who appear to believe speed limit signs include an offset of -10 (i.e. they drive at 40 in a 30, 50 in a 40 etc). So, a speed limit of 80 would mean people would actually drive at 90-100.
That's true. And there are also those who seem to think that some law of average applies - derestricted country road, fool in front bumbling along at 45mph, come to a village with a 30mph limit, and they just blindly carry on at 45mph. I slow down, and then not far out of the village, back up to 60, find them still bumbling along at 45mph. (When I used to have a 2-compressor, 5-trumpet airhorn and nearly 1000W of lighting on the front of the car I could usually persuade them to move over though.
)
The serious answer is a better use of technology to have variable speed limits that are realistic, so that people respect them more, and better enforcement as the quid pro quo. You talk about an 80mph limit - there are times when the limit could be twice that.
2) Our traffic is far too dense, and people don't appreciate correct inter-vehicular distances with our 70mph limit as it is. Ever tried to keep a 2-second or even 1-second gap on the M25? Some bu**er jumps into it within seconds... I've even had the car behind pull in, undertake, then cut into my gap. Many people would drive just as close at 90mph. We would see an increase in rear-end shunts on the motorways.
My #1 bugbear. It is also instructive to work out the gap in slower traffic needed for someone to pull into to allow faster traffic to pass without them being forced to slow down or drive too close.
For once our bizarre distance measures make life easy - 1mph is within 2.2% of 0.5 yards per second, so for practical purposes, a 2 second gap is 1 yard for every mph.
Say for argument's sake you are doing 80mph in the RH lane, the traffic on your left is doing 60mph, and the guy behind you wants to do 90mph. If you do the sums, you'll find that if you are not to be made to drive too close to the person in front of you, or the driver behind too close to you, or you to be made to slow down, you need a gap in the traffic on your left of 380 yards to be able to pull over - nearly ¼ of a mile.
That's the system I work to, and if you come up behind me, and there isn't a big enough gap to the left, I won't move over.
BTW - yes, I do maintain a 2 second gap (3 if it's raining) on the M25, and all motorways - at least in front of me, but there's not much I can do about the person behind me. Except brake firmly if someone pulls in front of me and I need to get the gap back to 2 or 3 seconds.
