Traffic Lights Fail - Traffic Flows Better

[Crossover]

Has anyone experienced this sort of thing? I heard on the radio this morning that a set of lights had failed on a junction I travel through on the way to work. Great, I thought, the traffic may not be quite so bad. Indeed, on arriving at said junction, the traffic wasn't backed up as far as normal, and very rapidly got through the junction at which the lights were out - certainly in comparison to yesterday when it was "situation normal" it probably took 5 mins to do what took me 1 min today.

The junction in question is actually a roundabout anyway, so really, the normal rules of using a roundabout were coming into play.

The junction in question is this:
https://www.google.co.uk/maps/@53.6...4!1siyCNyS7yWCLsCkVd_Y0tLA!2e0!7i13312!8i6656

On a typical day, the traffic is backed up to the Y junction a few hundred yards back:
https://www.google.co.uk/maps/@53.6...4!1sHsN9NJqPj3OBJHO4guvvAA!2e0!7i13312!8i6656

Invariably, when the lights on the Y junction change, traffic has nowhere to go thanks to the lights further down causing tailbacks and it can be quite a mammoth job to get through at times.

I did read recently somewhere that roundabouts work best with one leg not on traffic light control - though this being not much more than a mini roundabout, may not have quite such success with such a scheme

 

[Bletchleyite]

Has anyone experienced this sort of thing?

Yes, a number of times. Traffic lights do not exist to improve traffic flow - by definition they cannot do this, because there is a short period in each cycle when no traffic is flowing.

They exist either for safety or to *balance* flows (on roundabouts more likely the latter, as a roundabout on its own is safe enough).

I did read recently somewhere that roundabouts work best with one leg not on traffic light control - though this being not much more than a mini roundabout, may not have quite such success with such a scheme

That setup does mean that slightly less flow time is lost.

 

[carriageline]

I had this convo with someone the other day. The problem is, I'm sure during peak times it would make getting onto the roundabouts a lot harder.

 

[me123]

I did read recently somewhere that roundabouts work best with one leg not on traffic light control - though this being not much more than a mini roundabout, may not have quite such success with such a scheme

I'm sure you've read that on here!

It can happen, but it's also worth remembering that a failed set of traffic lights may improve the flow for the main flow, but traffic on the side street might be building up! That's exactly why they are a compromise solution. It's possible that one of the three arms of your roundabout had much worse traffic than it would otherwise have had. Of course, at a roundabout you have an already existing set of rules that people can and will automatically revert to - that would not be the same at a crossroads where the priorities could be a little less clear.

It's also not unknown for road planners to realise they've not come up with the best solution in the first place when something goes wrong, and change things based on that. For example, the Kingston Bridge segregated some Eastbound traffic during road works to improve the flow at the time of disruption. This was so effective at improving flow of traffic that it's now a permanent solution and remains in place to this day. So if the loss of traffic lights improved things for everyone, it's not impossible that it's been noted somewhere.
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I had this convo with someone the other day. The problem is, I'm sure during peak times it would make getting onto the roundabouts a lot harder.

Part time traffic lights would be the answer. They're used here in Livingston, and also in East Kilbride and a busy junction near Hamilton (to name but three places) - and they tend to work!

 

[deltic]

A lot depends on whether the traffic signals are dynamic or on fixed cycles. If the latter then they are optimised for a particular traffic flow which may not be the traffic flow in reality or at the time you travel through them. Roundabouts usually only need to be signallised when dealing with large volumes of traffic or the traffic flow is predominantly on a particular axis which as mentioned by others means that one traffic flow finds it hard to enter the roundabout.

Did some work on pushing the case for removing traffic signals, making them part time or moving to the continental system of flashing amber in less busy times. Some local authorities have removed signals but DfT are opposed to flashing amber signals due to the fact they exist on Pelican crossings and motorists will allegedly become confused by what they mean.

 

[Bletchleyite]

DfT are opposed to flashing amber signals due to the fact they exist on Pelican crossings and motorists will allegedly become confused by what they mean.

I'm not quite sure why that would be, given that both effectively mean "give way to conflicting traffic" in a sense.

 

[Tetchytyke]

I've seen it both ways. At the Milburngate roundabout in Durham years ago they had to put temporary lights in due to roadworks. Rather than the traffic carnage they expected, the flow worked better, so lights were permanently installed at the junction.

Roundabouts work well when all the traffic flows are roughly equal, meaning everyone gets a turn at getting out. They don't work when some traffic flows dominate. You see that issue at Haddricksmill junction in Gosforth. Traffic in a morning on the A189 southbound banks up for at least a mile as nothing can get on to the first roundabout, and this is because there's no traffic flow to balance out (and create a gap in) the cars heading westbound on the A191.

In your example, if the traffic flows on the A62 and A644 were equal you'd expect everything to move a bit more freely. The issue will come if one flow (e.g. turning right from the A644 on to the A62) dominated, meaning that nobody else could get out into the traffic.

 

[deltic]

I'm not quite sure why that would be, given that both effectively mean "give way to conflicting traffic" in a sense.

That would be my view as well but DfT saw it differently

 

[edwin_m]

No traffic signals means no timeslot for pedestrians and cyclists to cross safely. So if their time is available to other traffic it might flow more freely, but it's hardly fair on the more vulnerable road users.

 

[Busaholic]

In Truro, two roundabouts that had traffic lights installed but which were semi-permanently switched off had them activated and, in my experience, both have led to traffic jams at all times of the day that weren't there before, except in peak hours and,even then, to a lesser extent than now. One is the notorious Trafalgar roundabout, where the recently-installed offside lane bus lane had to be scrapped after three weeks.

 

[Kentish Paul]

Whenever the traffic lights failed on the roundabout at junction 10 on the M20 at Ashford the traffic moved far more easily than normal. Drivers would just filter in and out and things would move smoothly. It got rid of the cars waiting at the lights on a normal day.

 

[Bletchleyite]

No traffic signals means no timeslot for pedestrians and cyclists to cross safely. So if their time is available to other traffic it might flow more freely, but it's hardly fair on the more vulnerable road users.

Though if money is available, bridges and underpasses are best.

 

[me123]

^ Last time I suggested that on here, I was told that I was anti-pedestrian

 

[deltic]

Though if money is available, bridges and underpasses are best.

Best for who?

 

[me123]

(Right on cue...) Best for everyone, because all flows of traffic have a dedicated right of way. Cars don't have to stop to allow pedestrians to cross, pedestrians don't have to stop to allow vehicles through the junction.

 

[Bletchleyite]

Best for who?

Best for everyone, because the traffic flow is not interrupted, and the pedestrians are safer and never have to wait to cross.

There is a perception that underpasses are unsafe - the crime statistics in Milton Keynes (where there are a lot of them) do not bear this out at all, at least. I would expect that to be the same everywhere.

Make them well-lit with visible, obvious CCTV cameras, and ensure any vandalism is promptly removed, and they will feel safer, of course.

 

[Tetchytyke]

There is a perception that underpasses are unsafe - the crime statistics in Milton Keynes (where there are a lot of them) do not bear this out at all, at least. I would expect that to be the same everywhere

They're not unsafe but they're grotty and inconvenient. Look how few bridges have accessible ramps, rather than just stairs. Look how often underpasses- even in MK- end up flooded because of inadequate drainage.

Segregation is sometimes the answer but, actually, more often than not it isn't. I don't think it works in MK and I certainly don't think it works on the absolutely disgusting underpasses and bridges around the Central Motorway in Newcastle.

 

[deltic]

Best for everyone, because the traffic flow is not interrupted, and the pedestrians are safer and never have to wait to cross.

There is a perception that underpasses are unsafe - the crime statistics in Milton Keynes (where there are a lot of them) do not bear this out at all, at least. I would expect that to be the same everywhere.

Make them well-lit with visible, obvious CCTV cameras, and ensure any vandalism is promptly removed, and they will feel safer, of course.

It very much depends on the nature of the underpasses - those where there is a gentle slope down and up and clear sight lines are usually not a problem. Those that involve steps and or long ramps - where there are a multitude of exits and entrances are often a disaster and are often removed where possible. London's Elephant & Castle is a good example of this where all subways have been closed and crossings restored at street level. Sadly in London and other major cities subways have become sleeping places for the homeless and toilets for the anti-social and so are avoided where possible.

 

[Antman]

Whenever the traffic lights failed on the roundabout at junction 10 on the M20 at Ashford the traffic moved far more easily than normal. Drivers would just filter in and out and things would move smoothly. It got rid of the cars waiting at the lights on a normal day.

That junction is hell with or without lights, regularly delays ambulances on a blue light to William Harvey hospital.
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It very much depends on the nature of the underpasses - those where there is a gentle slope down and up and clear sight lines are usually not a problem. Those that involve steps and or long ramps - where there are a multitude of exits and entrances are often a disaster and are often removed where possible. London's Elephant & Castle is a good example of this where all subways have been closed and crossings restored at street level. Sadly in London and other major cities subways have become sleeping places for the homeless and toilets for the anti-social and so are avoided where possible.

Not just in London, I think subways are largely seen as a relic from the 60s and 70s and no longer fit for purpose. They've been filled in at many locations and replaced with better crossing facilities at street level.

 

[cjmillsnun]

Not just in London, I think subways are largely seen as a relic from the 60s and 70s and no longer fit for purpose. They've been filled in at many locations and replaced with better crossing facilities at street level.

Better in what way? Maybe they don't stink of wee and don't have graffiti all over them however street level crossings reintroduce the risk of getting run over and cause traffic delays. The very thing subways were designed to prevent. Footbridges also work but have their own issues as they have to be high enough to allow high vehicles and therefore need long ramps to allow for accessibility.

 

[edwin_m]

Better in what way? Maybe they don't stink of wee and don't have graffiti all over them however street level crossings reintroduce the risk of getting run over and cause traffic delays. The very thing subways were designed to prevent. Footbridges also work but have their own issues as they have to be high enough to allow high vehicles and therefore need long ramps to allow for accessibility.

So you'd be quite happy for the inside of your car to stink of wee and have graffiti all over it, because you consider that to be acceptable for people who don't happen to be inside a car, so that those that are can have a marginally quicker journey.

Give me a proper pedestrian crossing over a subway any day. Urban roads are for all users to share, not to create exclusive raceways for vehicles.

 

[Mojo]

So you'd be quite happy for the inside of your car to stink of wee and have graffiti all over it, because you consider that to be acceptable for people who don't happen to be inside a car, so that those that are can have a marginally quicker journey.

Give me a proper pedestrian crossing over a subway any day. Urban roads are for all users to share, not to create exclusive raceways for vehicles.

On the other hand, I hate vegetating for unspecified amounts of time at pedestrian crossings whilst cars zoom past.

 

[PermitToTravel]

The pedestrian crossing outside my house has recently been re-timed so that pressing the button will instantly turn the road traffic signals amber, as long as the crossing hasn't been activated in the past couple of minutes or so. It's brilliant.

 

[me123]

^ Yes. Obviously it only works in situations where the lights aren't synchronised with a junction further down the road, but it's brilliant. There's nothing more infuriating as a driver and pedestrian than pressing a button, waiting 30 seconds, traffic clears, pedestrian crosses anyway, then traffic lights turn red stopping the traffic for no reason. It's a common sense solution.

 

[Peter Mugridge]

There's nothing more infuriating as a driver and pedestrian than pressing a button, waiting 30 seconds, traffic clears, pedestrian crosses anyway, then traffic lights turn red stopping the traffic for no reason. It's a common sense solution.

This set https://www.google.co.uk/maps/@51.3...4!1s8m3ZqlHvPY3kj7tHFQ-ZfQ!2e0!7i13312!8i6656 when it was first installed would react instantly upon the button being pressed except when within 30 seconds of a previous cycle.

After a few months it was changed so that at all times except when no traffic at all is coming it will make you wait at least 40 seconds.

 

[underbank]

I wouldn't mind if traffic lights were set so that the busier road got priority, but many times, I've been stuck for 5 or 10 minutes in a stop/go traffic queue, only to reach the cause which is either a pedestrian crossing or junction where the cars on the side street or pedestrians only have to wait 30-60 seconds for the lights to change in their favour. Surely if the majority, i.e. cars on the main road, are having to wait several minutes, then the pedestrians and side street motorists should have to wait a similar amount of time and should not get priority of a far shorter waiting time.

 

[Bletchleyite]

I wouldn't mind if traffic lights were set so that the busier road got priority

On roundabouts, the *whole point* is that they don't. It can become impossible to get out of certain quieter roads at certain times.

 

[AM9]

I wouldn't mind if traffic lights were set so that the busier road got priority, but many times, I've been stuck for 5 or 10 minutes in a stop/go traffic queue, only to reach the cause which is either a pedestrian crossing or junction where the cars on the side street or pedestrians only have to wait 30-60 seconds for the lights to change in their favour. Surely if the majority, i.e. cars on the main road, are having to wait several minutes, then the pedestrians and side street motorists should have to wait a similar amount of time and should not get priority of a far shorter waiting time.

The whole reason that there is a queue of traffic is that there is too much traffic. Pedestrians don't take 10-15ft of road space, nor do they produce CO (or much Co2). Trying to make pedestrians wait more than about 1 minute would result in them crossing without the aid of lights/zebra crossing.
If the pedestrians were banned from crossing the road altogether, how much faster do you think the main stream of traffic would be?

 

[AndrewE]

This set https://www.google.co.uk/maps/@51.3...4!1s8m3ZqlHvPY3kj7tHFQ-ZfQ!2e0!7i13312!8i6656 when it was first installed would react instantly upon the button being pressed except when within 30 seconds of a previous cycle.

After a few months it was changed so that at all times except when no traffic at all is coming it will make you wait at least 40 seconds.

You are lucky - the ones directly outside Crewe Station top seem to make you wait 90 seconds (millionth note to self - I must stop exaggerating) in the dirty spray from road traffic, to the point where those waiting to cross block the path for other pedestrians. As I understand it they have a special feature that cancels the crossing request if it detects that people have already gone in a gap in the traffic - Nothing to detect a blocked pavement, or stationary traffic and give pedestrians priority, of course. You would think that the local authority are in league with Virgin in trying to discourage the use of Crewe Station...

What makes it more frustrating for the pedestrian is that in an attempt to reduce traffic on Nantwich Rd money has been spent on "traffic calming" and there is now a complete bypass round the south of Crewe.

 

[Crossover]

You are lucky - the ones directly outside Crewe Station top seem to make you wait 90 seconds (millionth note to self - I must stop exaggerating) in the dirty spray from road traffic, to the point where those waiting to cross block the path for other pedestrians. As I understand it they have a special feature that cancels the crossing request if it detects that people have already gone in a gap in the traffic - Nothing to detect a blocked pavement, or stationary traffic and give pedestrians priority, of course. You would think that the local authority are in league with Virgin in trying to discourage the use of Crewe Station...

What makes it more frustrating for the pedestrian is that in an attempt to reduce traffic on Nantwich Rd money has been spent on "traffic calming" and there is now a complete bypass round the south of Crewe.

The ones in Stafford were exactly the same when I was at uni there a few years back. It wasn't unusual for them to be at green for vehicles, when it was clear as far as the eye could see in both directions and then change to allow pedestrians to cross the second a car turned up. We used to play a game as to how far from the crossing we could get, after using it, before the lights would change...it was sometimes quite a few metres!

Some of the ones we have in the town where I currently live also tend to hang a bit, but there are traffic light controlled junctions either side (both also with pedestrian crossings) which is probably why. However, at least one of them seems to clear the crossing request if it detects the crossing and nearby pavement clear where someone has crossed out of sequence
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A lot depends on whether the traffic signals are dynamic or on fixed cycles. If the latter then they are optimised for a particular traffic flow which may not be the traffic flow in reality or at the time you travel through them. Roundabouts usually only need to be signallised when dealing with large volumes of traffic or the traffic flow is predominantly on a particular axis which as mentioned by others means that one traffic flow finds it hard to enter the roundabout.

It is the main junction between the M62 J25, the road to Huddersfield and the road to Dewsbury, so it is a hellishly busy junction (there is a real need for a bypass, but that isn't going to happen anytime soon). The lights feel like they are often on fixed cycles, but I think that is just that all legs are busy and need equal weighting at peak times, when I usually travel. In reality, I think they are dynamic as they seemed to change a lot quicker when I travelled in the run up to Christmas when the roads were much quieter. It may just be they need somehow better co-ordination with the "upstream" junction - however, as traffic can also be queued all the way back to this junction from the M62 and sometimes from Huddersfield too, there are likely to be bigger issues on traffic than this roundabout singularly.