A question for everyone that speeds.

[SafeSpeed]

There should not be any traffic lights in 60 or 70 mph zones. Ever. I don't know if this is in the rules anywhere or not, but we used to be very good at ensuring that traffic lights were only in 30s and 40s.

I think we have discussed this before, but in Cheshire there are plenty of traffic lights at junctions of NSL 60 and 70 mph roads (e.g. A49/A533, A540/A550, A34/A537 etc) and most have them have been there for as long as I can remember. It's not a recent phenomenon.

Yes, you're right, and thanks for reminding me. Nowhere that I've ever lived has had traffic lights on 60 or 70 roads.

If we do calculations on the approach speed of a green light in unknown condition (i.e. we haven't just see it change to green), and allow ourselves 0.75 seconds of reaction time and 0.45g (i.e. half effort) braking, then the maximum safe approach speed is 44mph. See figure 6 on page:

http://www.safespeed.org.uk/braking.html

Note the point (3, 44) on the line.

If we are able to get away with trafic light systems on 60 and 70mph zones, I don't really know how we do it. If I was a traffic engineer "forced" to install traffic lights in a 60mph zone I would insist on a 2 second all-red phase, and I wouldn't accept that we could use a red light camera.

[PeterE]

Yes, you're right, and thanks for reminding me. Nowhere that I've ever lived has had traffic lights on 60 or 70 roads.

I think they are particularly prevalent in the North-West. The prime example must be the A580 East Lancs Road referred to above, which has at least 10 signal-controlled crossings in its 70 mph section, and which is a near-straight road which some drivers do treat as "a bit of a racetrack".

I think it may now be officially recommended that traffic lights are not designed in to new NSL roads (not that many of such are built anyway )

If we are able to get away with trafic light systems on 60 and 70mph zones, I don't really know how we do it. If I was a traffic engineer "forced" to install traffic lights in a 60mph zone I would insist on a 2 second all-red phase, and I wouldn't accept that we could use a red light camera.

I think it's the phenomenon we've remarked on before of a bit of give-and-take making the best of a solution that falls some way short of the ideal.

And I would say a signal-controlled crossroads between two NSL A-roads is in practice likely to be much safer than a totally uncontrolled crossroads where one road has priority, given comparable traffic volumes.

[PeterE]

I've raised the question of signals on NSL roads on the SABRE roads forum, which resulted in this thread which you may find interesting, particularly message #8 from a professional highway engineer.

Provided drivers act sensibly and don't put the hammer down when approaching a green light I really don't see that they represent a safety problem.

[Homer]

Yes, you're right, and thanks for reminding me. Nowhere that I've ever lived has had traffic lights on 60 or 70 roads.

I think they are particularly prevalent in the North-West. The prime example must be the A580 East Lancs Road referred to above, which has at least 10 signal-controlled crossings in its 70 mph section, and which is a near-straight road which some drivers do treat as "a bit of a racetrack".

A64 York bypass had two sets in the NSL dual carriageway. Both have now been removed.

Worse than that, the M606 now terminates at a set of traffic lights, just beyond a slight crest.

[Roger]

Aren't there slip roads on to motorways with traffic lights somewhere - to reduce allowed traffic merging? Or am I thinking of abroad and telly? Never (knowingly) negotiated any myself I hasten to add.

[PeterE]

Aren't there slip roads on to motorways with traffic lights somewhere - to reduce allowed traffic merging? Or am I thinking of abroad and telly? Never (knowingly) negotiated any myself I hasten to add.

There are traffic lights at some of the M6 junctions in the West Midlands to control access on to the motorway - however these are probably at locations where the non-motorway road is only a 30 or 40.