Traffic Lights on slip roads.

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Mr. B

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Time for a whinge.

Not sure if this topic has been covered before so here goes.

Does anybody have anything positive to say about traffic lights positioned towards the bottom of m/way entry slip roads ?

They have been around for a number of years now and I just don't get it.

I understand the general idea in that they are designed to asssit traffic entering a congested m/way but in my experience they just don't work.

Having worked on the m/way network for a number of years I have come to the conclusion that they are a total waste of time and money.

They are only in operation at peak times but how can they assist traffic joining an already busy m/way ?

If lane 1 is already congested what difference are traffic lights going to make ?

Some traffic lights are quite amusing to watch because by the time they have changed to green and you have selected first gear they are changing back to amber.

So in a nut shell I just get them especially the ones that I have seen over the years.

Opinions anybody ?

Whinge over - off to bed.
 
Designed by a committee in Europe because some ministers brother had a job lot to get rid of perhaps?

Seriously though I don't get it either, they have them at Reading and as far as I can see they don't work.
 
Well, they dont offer a complete solution, that's for sure.
However, by releasing traffic at very short bursts (normally the green doesn't last more than 5s), the idea was to (believe it or not) improve traffic merging between motorway and slip road.

I have seen this work and work quite well, the only time it fails is when the main drag becomes badly congested on its own - then it makes no difference at all.
 
The installed them on a couple of junctions of the M27 to aid traffic flow. They didn't work and after a while they removed them
 
They still have them at J11 on the M27, I rarely meet them on green.
 
Traffic lights such as this are usually used where there are more than one lane of joining traffic, but there is limited space for extending the slip road.

If used when conditions don't require them, them I can see why some may see them as pointless. However the real benefit is when traffic is moving on the motorway, say 40/50 mph, but traffic is very densely packed on both the mptorway and slip road.

In these conditions there is a high risk that a vehicle joining from the slip road has correctly adjusted it's speed to join without inconveniencing drivers on the motorway, but cannot merge in, and must abort by braking hard or sharply moving into a neighbouring lane.

The vehicles either side, and especially the vehicle behind, will also be travelling at 40/50 mph and importantly will be watching their side mirrors closely, and so may not anticipate or even see a sudden manoeuvre in front of them until it's too late.

Of course, ensuring there's safe space all round and anticipating the manoeuvre would prevent that happening, but sadly most drivers don't.
 
They still have them at J11 on the M27, I rarely meet them on green.

Not at the bottom of the slip roads as you come on they don't- Just at the top of the slip road coming off the motorway and on the roundabout itself.
 
I regularly use junctions with these on and while it first appears annoying to have to wait then go, it does mean there is only a small amount of traffic joining the already saturated motorway.
 
And that traffic has been slowed down by the frequent light changing so is at a much better speed for merging with the congested lanes.
 
They are known as b*ll-ache lights in the Johnsco household.
 
I agree that the lights on slip roads are a bad idea, but most of the problem on traffic joining a busy motorway stems from the fact that usually two lanes of traffic come down the slip road and have to then get into one already full lane on the main carriageway.
And no one moves across to let the joiners in.............


fetching coat (and hard hat!!!)
 
flying haggis said:
I agree that the lights on slip roads are a bad idea, but most of the problem on traffic joining a busy motorway stems from the fact that usually two lanes of traffic come down the slip road and have to then get into one already full lane on the main carriageway. And no one moves across to let the joiners in............. fetching coat (and hard hat!!!)

And of course it slows down the idiots who charge down the slip road and aim directly to lane 3 or 4.
 
Little video showing how the lights work and that thanks to them there was no congestion between main carriageway and the slip road.

There was congestion on that stretch, but it was caused by something else further down the road and backed up.

[YOUTUBE HD]LgkmTu0nMjs[/YOUTUBE HD]
 
I agree that the lights on slip roads are a bad idea, but most of the problem on traffic joining a busy motorway stems from the fact that usually two lanes of traffic come down the slip road and have to then get into one already full lane on the main carriageway.
And no one moves across to let the joiners in.............

I hate them but they do seem to work. And it's not always about two lane slips either - there's one that I pass with just a single lane and the lights basically throttle the traffic flow make sure the taffic merges more smoothly.

Really they shouldn't be necessary - but an awful lot of drivers seem to find it next to impossible to understand how to control speed, space and merge - and the idea that if they were more strategic that traffic flow wouldn't brake down in the first place and everybody would benedfit.

:doh::mad::wallbash::crazy:
 
Even the lights on roundabouts under A roads and motorways are a PITA, although often not much option

Many a happy moment at the M25/A1 junction, watching numpties doing drag races followed by brake tests
 
I think they're great, helps the flow on the main road which tails back if too much traffic is trying to join. They're not for the joining traffic.

They have them in the states a lot as well as car pool lanes for cars with more than 1 person in them.
 

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