Bus controlled traffic lights

brynpoeth
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Re: Bus controlled traffic lights

Postby brynpoeth » 17 Mar 2019, 8:23am

Many French towns have built new tram systems in recent years, even Paris
Cycling-of course, but it is far better on a Gillott
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wjhall
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Re: Bus controlled traffic lights

Postby wjhall » 18 Mar 2019, 11:14am

'We' are not letting go of bus lanes, but taking them over, remember, this is a cycling group, I think.

The point is that the signals would be optimised to blow the whole half mile congestion plug through with the bus. On a 20 mph road this would take 90 s after which some other optimisation would resume, probably weighted for a while against the bus route, until the next bus bearing plug appeared. Eventually, with frequent enough buses, this would completely close side roads, but since in many places we are talking about 5 minute intervals as suitable for trams, this will be some way in the future.

Closing side roads seems to be the basis of the current Bristol proposals for the A4018, but by repainting road markings rather than traffic light sequencing. Being well beyond what would be needed for any plausible bus frequency suggests that the real purpose is to accommodate a much increased flow of general traffic from new developments to the north of the city, bus lanes being used as a cover for this.

Bus lanes have the effect of speeding buses from one congestion point to another, after which, without bus control, they could get stuck for up to a light cycle.


The railway analogy is useful. Consider the way in which regulation and control are used to allocate priorities and trains between loops, fast/main and slow/relief lines.

The situation described in Leeds seems to be a good example of creating something that is apparently designed to favour buses and cyclists, but not sufficiently actually to have much effect.

I am currently reading a paper about systems in Melbourne (3) drawn to my attention on another forum. Interestingly it is dated 2018, suggesting that these systems are fairly novel, despite the technology being well established. I had expected to be deluged with comments on the lines of 'surely you know this has been done everywhere for ages'.

(3) Bus & tram priority in Melbourne – conference paper
http://www.jctconsultancy.co.uk/Symposi ... tralia.pdf

Bmblbzzz
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Re: Bus controlled traffic lights

Postby Bmblbzzz » 18 Mar 2019, 12:23pm

wjhall wrote:'The point is that the signals would be optimised to blow the whole half mile congestion plug through with the bus.

That would require half a mile (more in fact, if the cars are to be moving) of uncongested road beyond the signals. That's not going to happen with current vehicle usage.

Closing side roads seems to be the basis of the current Bristol proposals for the A4018, but by repainting road markings rather than traffic light sequencing. Being well beyond what would be needed for any plausible bus frequency suggests that the real purpose is to accommodate a much increased flow of general traffic from new developments to the north of the city, bus lanes being used as a cover for this.

Interesting and highly plausible idea.

Bus lanes have the effect of speeding buses from one congestion point to another, after which, without bus control, they could get stuck for up to a light cycle.

Yes. As a start we could at least make bus lanes continuous. Signal optimisation would help too, but without dedicated bus lanes it just means the lights are optimised for one set of congestion over another.

Pete Owens
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Re: Bus controlled traffic lights

Postby Pete Owens » 18 Mar 2019, 5:40pm

wjhall wrote:'We' are not letting go of bus lanes, but taking them over, remember, this is a cycling group, I think.


Not only do we already use bus lanes – but these are the ideal cycling environment (even from a segregationist perspective). They present a virtually motor traffic free environment – Not only are buses relatively infrequent, they also make progress at approximately cycling speed; even if you were to ride the entire length of a bus lane on a busy bus route you are unlikely to encounter a single bus.

Unlike a cycle path you will not find your passage obstructed by trees, bollards, fences, bins, or other objects – and if the route is following a bus route then you can guarantee that you will find bus stops en-route. Unlike a cycle path you will not have to give way at every side road or private drive. Unlike a cycle path, a bus lane is guaranteed to be of adequate width. And when you reach a set of traffic lights you will get a stage in the lights that will enable you to clear the whole junction, rather than hop from cattle pen to cattle pen at times to suit the convenience of motorists.

So yes, what you are advocating is giving up the best cycle facility there is and replacing it with something that will almost certainly be vastly inferior. And that is without considering the loss of utility to bus passengers. People have very little incentive as it is to take the bus. If you cause them delays then some will switch to cars.

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mjr
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Re: Bus controlled traffic lights

Postby mjr » 18 Mar 2019, 6:23pm

Not only do we already use bus lanes – but these are the ideal cycling environment (even from a segregationist perspective). They present a virtually motor traffic free environment – Not only are buses relatively infrequent, they also make progress at approximately cycling speed; even if you were to ride the entire length of a bus lane on a busy bus route you are unlikely to encounter a single bus.

Anybody tempted to believe that should go ride Euston Road or the bits of CS7 that are still only bus lanes. Then compare with the bits of CS6 or CS3 which are built to recent standards (so no obstructions by trees and so on, priority over side roads and adequate width).

There's simply no comparison between enjoying a proper cycleway and riding along trying to sprint to keep ahead of the following bus, wondering whether the next motorist to put your life in danger will be a bus, a black cab, a chancing-it minicab or simply a regular motorist not looking before pulling into the bus lane.

And when you reach a set of traffic lights you will get a stage in the lights that will enable you to clear the whole junction, rather than hop from cattle pen to cattle pen at times to suit the convenience of motorists.

Aren't bus advance start phases still really really rare? Most of Norfolk's bus lanes evaporate before the lights, dumping you in amongst a load of turning motorists with at best and Advanced Stop Line if you're lucky to get a half-second start on the motorists behind. The one I can think of which goes all the way up to the lights, outside King's Lynn Rail Station, is not available for cycling (and it's not particularly needed, with a 3.5m cycleway next to it).

So yes, what you are advocating is giving up the best cycle facility there is and replacing it with something that will almost certainly be vastly inferior. And that is without considering the loss of utility to bus passengers. People have very little incentive as it is to take the bus. If you cause them delays then some will switch to cars.

I think there should be bus lanes - but they're very poor cycle lanes and should be as well as, not instead of. They might be OK on low-priority routes, which seems to be how most of central London is going, with the cycle route network slowly developing to avoid bus lanes on bus roads. They're available if you like the extreme sport and big roads, but you're not often directed to use them any more.
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Bmblbzzz
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Re: Bus controlled traffic lights

Postby Bmblbzzz » 18 Mar 2019, 7:11pm

mjr wrote:
And when you reach a set of traffic lights you will get a stage in the lights that will enable you to clear the whole junction, rather than hop from cattle pen to cattle pen at times to suit the convenience of motorists.

Aren't bus advance start phases still really really rare? Most of Norfolk's bus lanes evaporate before the lights, dumping you in amongst a load of turning motorists with at best and Advanced Stop Line if you're lucky to get a half-second start on the motorists behind. The one I can think of which goes all the way up to the lights, outside King's Lynn Rail Station, is not available for cycling (and it's not particularly needed, with a 3.5m cycleway next to it).

Pete Owens will be along sooner or later to explain, but where do you get this idea of bus advance start phases from? They are, as you say, really rare and he certainly didn't mention them. I presume he was just referring to the normal traffic light phase, which gives enough time to clear the whole junction. I'd note that, at least outside London, cycle advance start phases are also really rare, as are cycleways which maintain priority over side roads -- hence being forced to jump from pen to pen.

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Re: Bus controlled traffic lights

Postby Bmblbzzz » 18 Mar 2019, 7:18pm

Pete Owens wrote:
wjhall wrote:'We' are not letting go of bus lanes, but taking them over, remember, this is a cycling group, I think.


Not only do we already use bus lanes – but these are the ideal cycling environment (even from a segregationist perspective). They present a virtually motor traffic free environment – Not only are buses relatively infrequent, they also make progress at approximately cycling speed; even if you were to ride the entire length of a bus lane on a busy bus route you are unlikely to encounter a single bus.

It's a car type of cycling speed though. The average speed from origin to destination may be similar but the peaks are significantly higher and there's far more standing time. Cycling in a bus lane means being continually overtaken by one or two buses and passing them when they're at stops; probably preferable to the same with a multitude of cars though.

Unlike a cycle path you will not find your passage obstructed by trees, bollards, fences, bins, or other objects – and if the route is following a bus route then you can guarantee that you will find bus stops en-route. Unlike a cycle path you will not have to give way at every side road or private drive. Unlike a cycle path, a bus lane is guaranteed to be of adequate width. And when you reach a set of traffic lights you will get a stage in the lights that will enable you to clear the whole junction, rather than hop from cattle pen to cattle pen at times to suit the convenience of motorists.

All true, sadly.

So yes, what you are advocating is giving up the best cycle facility there is and replacing it with something that will almost certainly be vastly inferior. And that is without considering the loss of utility to bus passengers. People have very little incentive as it is to take the bus. If you cause them delays then some will switch to cars.

Yep, bus lanes are for buses and their passengers (and indirectly therefore beneficial to everyone who eg breathes).

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mjr
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Re: Bus controlled traffic lights

Postby mjr » 18 Mar 2019, 7:25pm

Bmblbzzz wrote:
mjr wrote:
And when you reach a set of traffic lights you will get a stage in the lights that will enable you to clear the whole junction, rather than hop from cattle pen to cattle pen at times to suit the convenience of motorists.

Aren't bus advance start phases still really really rare? Most of Norfolk's bus lanes evaporate before the lights, dumping you in amongst a load of turning motorists with at best and Advanced Stop Line if you're lucky to get a half-second start on the motorists behind. The one I can think of which goes all the way up to the lights, outside King's Lynn Rail Station, is not available for cycling (and it's not particularly needed, with a 3.5m cycleway next to it).

Pete Owens will be along sooner or later to explain, but where do you get this idea of bus advance start phases from? They are, as you say, really rare and he certainly didn't mention them. I presume he was just referring to the normal traffic light phase, which gives enough time to clear the whole junction.

"you will get a stage in the lights that will enable you to clear the whole junction" - if it's just the normal stage (phase means something different in traffic light jargon) then you're getting no time to clear the junction before conflicting turning vehicles are present, plus they are currently timed for motorists and often don't give sufficient time for cycling across a large junction from a stop, so cyclists can easily be caught out mid-junction when cross-traffic is released.

If that's what was meant, it's another disconnection of the bus lane fantasists from the reality on our roads.
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Re: Bus controlled traffic lights

Postby Bmblbzzz » 18 Mar 2019, 8:15pm

So what's the difference between stage and phase in this context?

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Re: Bus controlled traffic lights

Postby mjr » 18 Mar 2019, 10:05pm

Bmblbzzz wrote:So what's the difference between stage and phase in this context?

If I remember correctly, a phase is a movement controlled by a signal IIRC so if there are independent left turn, right turn and straight ahead arrows from a direction, for example, that's three phases, but they might all be lit green together and that's a stage. A different combination of greens would be another stage. And so on.

There are better explanations online, even in the traffic signal manuals, but they're longer as well as more precise.
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