Green Man Authority

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  • https://usa.streetsblog.org/2018/07/23/n­ew-traffic-signals-in-london-will-to-giv­e-pedestrians-the-green-light-by-default­/

    This popped up in my Twitter feed today. Not cycling infra but looks good.

    Does anyone know if LCC has been consulted over this to make sure that the traffic detection system is going to pick up cyclists?

  • Brilliant idea.

    Most traffic lights can detect cyclists. That shouldn't be a problem.

  • Most isn't enough. I know of a handful on signed cycle routes that don't and its ridiculous enough having to wait for a car to come along and trigger them. Or to have to shuffle back because you've realised you've pulled up too far out in the ASL to be spotted.

    For a trial like this, absolutely everything should be spot on?

  • That is unusual in London. Elsewhere quite common unfortunate

    Worth notifying the LA where this is the case.

  • Can't say I'm that enthused by the idea. In quiet spots it's not needed, it's already quiet. In busy spots there will be enough cars to make it an issue of time allocation, as it already is.

    I think I've missed the point somewhere...

  • The design of light-controlled crossings almost universally communicates to drivers that they have a default priority over any pedestrian interest in crossing the road. For as far as line of sight is available there is a green light indicating that they can travel up to as close to the speed limit as other traffic and road furniture allows. This naturally creates a hierarchy that tells people in cars that they are more important in that space than people not in cars. This in turn contributes to the attractiveness of private vehicles as a mode of transport. Light controlled crossings tell pedestrians that they are expected to wait on a pre-defined and limited inconvenience of motorists.

    This change in operation of the lights inverts that priority. Pedestrians are always told that they can cross without waiting unless told otherwise. In the meantime, motorists approaching the crossing are told by a red light that they are expected to slow down and wait, like pedestrians usually are, until they are given permission to proceed.

    You're right that they probably are of limited effectiveness in quiet spots, but then quiet spots are more likely to be served by zebra crossings anyway. But traffic flow anywhere already varies according to time of day and demand for local facilities. So even in a busy spot there will be times where traffic flow diminishes and the green man authority comes to the fore and puts pedestrians first.

    For some people, a road that isn't that busy is one that will be crossed regardless of whether there's a green man or a red man showing. You might not even push the button, just wait for an appropriate gap in the traffic and walk across. But for others, perhaps less able-bodied or encumbered by a pram, they're a lot more likely to wait for an indication that motor traffic is being told to wait for them. Something like this makes that crossing space a lot more equal for them.

  • I do wonder how this will work with visually impaired people. Presumably anyone pushing the crossing button while it's in its default green mode will simply trigger an audible crossing alert.

  • Does anyone know if LCC has been consulted over this to make sure that the traffic detection system is going to pick up cyclists?

    It would be cheaper to move to a"red means yield for bikes" rule like the one in Paris.

  • How does that work?

  • I really don't see how this will help at all.

    In quiet spots its hardly needed anyway because there will be sufficient gaps in traffic to cross.

    In busy spots the lights will constantly sense vehicles approaching so will remain red for pedestrians just as much as they do now. Any other setup on a busy road would never be allowed, because the traffic capacity would be severely compromised

    What am I missing?

  • Yup, it smells strongly of Khan's politics. Grand gesture that means next to nothing in terms of what happens in reality.

    If he wants to make a difference then explicitly state the tfl will amend their modelling goals to allow more green man time. But that's politically difficult so I won't hold my breath.

  • In quiet spots its hardly needed anyway because there will be sufficient gaps in traffic to cross.

    I think that depends on whether you have any impairments on your mobility such as disability, or being a older and not quite as quick on your toes as someone under the age of 60, or maybe walking along with a small child or pushing a pram. Fuck those people apparently.

    And I'm confused by this notion of either quiet or busy. Maybe things have changed since I was last in London but near where I live traffic volumes don't suddenly shift from cul-de-sac in a residential neighbourhood at 3am and fast flowing dual carriageway during rush hour. There's quite a lot of space in between those two and I can easily think of many roads that fill them.

  • Backstop:

    Can't say I'm that enthused by the idea. In quiet spots it's not needed, it's already quiet. In busy spots there will be enough cars to make it an issue of time allocation, as it already is.

    I think I've missed the point somewhere...

    inappropriate_bike:

    In quiet spots its hardly needed anyway because there will be sufficient gaps in traffic to cross.

    In busy spots the lights will constantly sense vehicles approaching so will remain red for pedestrians just as much as they do now. Any other setup on a busy road would never be allowed, because the traffic capacity would be severely compromised

    What am I missing?

    Well, a number of things. Firstly, it's a lot harder to detect pedestrians than vehicles, which are generally in the carriageway. Pedestrians appear 'suddenly', from shop doorways, from subways, etc., they walk along the street on the footway in parallel to the carriageway and then want to cross the carriageway at a pedestrian crossing. The latter means that they take a 'sudden' small turn of about 90 degrees towards the carriageway. It will give them a big advantage if at that time the light is already green and they don't have to check themselves and wait, a big increase in walking comfort. Also, as for 'there will be sufficient gaps in traffic to cross'--sure, that's possible in London and most people do it. But think of parents with small children or nervous adults, e.g. people with mobility difficulties or elderly people, who might take a long time to cross the carriageway and who prefer to cross at a formal pedestrian crossing with a green man. Also, a small number of tourists might come from jurisdictions where crossing on red is unlawful, e.g. Germany, and who would otherwise wait until the lights turn green.

    Secondly, remember that the main issue with through motor traffic in London is in the morning peak hour and to a lesser extent in the more spread-out evening peak hours. Basically, most of the nervousness about design and carriageway space and signal timings is mainly because of peak hour traffic volumes. At other times of the day, even 'busy' streets will have large gaps between vehicles and some that take high peak flows will even be fairly quiet. It's not as if 'quiet' and 'busy' streets are contraries, and there's plenty of scope for these measures to make a big difference even on main streets. (Clearly, there are streets like the A501 Inner Ring Road that are far more busy with motor traffic than they are ever quiet, and I don't expect that these measures will be introduced there, but most middle-ranking A-streets certainly qualify.)

    Thirdly, a very important aspect of the success of such traffic signals will undoubtedly be whether they cut off large pedestrian flows too soon (i.e., as a vehicle approaches) or whether there will be some way of allowing for large numbers of walkers (e.g., people emerging from an Underground station) to be detected and for the signals to change only when the pedestrian flow has slowed to a trickle or all have crossed. That seems to me the most technically difficult aspect. I imagine that TfL probably envisage that this problem will be managed by either/both intergreen time or/and 'pedestrian countdown' (although the latter would make signal operation much less flexible in the event of a vehicle being detected). I'm not sure how that would work.

    Fourthly, London's essentially a walking and public transport city, and the vast majority of Londoners get around in this way (and as walking is our default mode of transport, we all benefit, even if cycling, e.g. when you're looking for a parking space and only spot too late that the only available one is on the other side of the street), so that this will undoubtedly be beneficial to a vast number of people.

    Finally, at the moment this attention-grabbing measure is actually only envisaged in ten locations. The vast majority of TfL's work is taken up with SCOOT, which isn't new but fairly old hat by now. Pedestrian SCOOT was trialled in 2014:

    https://tfl.gov.uk/info-for/media/press-­releases/2014/march/tfl-to-launch-worldl­eading-trials-of-intelligent-pedestrian-­technology-to-make-crossing-the-road-eas­ier-and-safer

    @skydancer, cyclist SCOOT began to be trialled a year later:

    https://tfl.gov.uk/info-for/media/press-­releases/2015/june/new-pioneering-trials­-to-detect-cyclists-at-junctions-begin-i­n-london

    I don't know how far this has been rolled out by now, but I expect that there are still plenty of SCOOT systems in London that don't detect cyclists.

    Now, I think that SCOOT is a mixed bag. It's obviously appreciated by many people if delays are reduced in this way, but I believe it can also serve to, over time, increase the flows it detects. I don't have evidence for that, but generally where better provision is made for flows that are already high, these flows will increase in volume, as per predict-and-provide; here, 'detect-and provide'. The biggest problem in transport policy is to do with unevenness of flows (i.e., providing for very high flows and dealing with the consequences of where flows are extremely small and don't sustain economic activity while the places with high footfall and wheel-roll benefit disproportionately), and I think SCOOT is very likely to exacerbate it, even where pedestrian flows are concerned. But, as I say, I have no evidence, it's just a logical consequence. Clearly, economic well-being depends to some extent on concentration of activity, but we have long passed the point where this is sustainable or otherwise advisable.

  • ^ Some of that was already said by @The_Seldom_Killer but I only just saw his post.

  • @Oliver Schick - I always find these discussions fascinating; could you recommend any resources on urban (transport) design that give a good overview of the basics (textbooks? CROW manual?)?

  • Well, there are lots of 'introduction to highway engineering' or 'introduction to traffic management' books and books on transport policy about, but I wouldn't recommend any of those that I know, which is partly why I've been writing my own for some time. You can definitely read some of them, but if you want to gain an understanding of the issues, there's nothing better than becoming an activist. The books won't tell you that unless you then embark on a related career and gain actual experience.

    On the cycling side, the best book (out of a bad field, it has to be said) is undoubtedly 'Bicycle Transportation' by John Forester, but I wouldn't recommend it, either, as it's outdated (came out in the 70s and hasn't aged well, I think), the writing style is turgid (very repetitive and rather obsessive), and it always brings people out in fisticuffs because of Forester's controversial conclusions (some of which I agree with and others of which I don't agree with). He's very good on some things, less good on others.

    A good recent book, but more of a history book and not what you're looking for, is Oldenziel et al., 'Cycling Cities: The European Experience'.

  • What about the LCDS?

  • I'm not sure you've said anymore than when it's quiet it's quiet enough to be unneeded and and when it's busy it comes down to tfl priorities. Unless there's some concomitant desire to improve the importance of pedestrians this won't change anything...

    We don't need fancy grand ideas, we need Khan to say to tfl, lower the importance you give to motor traffic in junction design. Until and unless he does that, nothing has happened except some headlines...

  • I'm not sure you've said anymore than when it's quiet it's quiet enough to be unneeded and and when it's busy it comes down to tfl priorities.

    Haha, no, I've said considerably more than that.

    Unless there's some concomitant desire to improve the importance of pedestrians this won't change anything...

    Er? Where has it not been clear that this is precisely Khan's desire?

    We don't need fancy grand ideas, we need Khan to say to tfl, lower the importance you give to motor traffic in junction design. Until and unless he does that, nothing has happened except some headlines...

    This measure isn't a 'fancy grand idea', it's a perfectly sensible, workmanlike step that will most certainly change the pedestrian environment for the better. Obviously, it's still limited in its scope with only ten locations, but once rolled out more widely it'll be seen as important.

    As for junction design (in the peak hour, and along the various routes into Central London), you won't get a different approach until network-wide problems are addressed, as I keep banging on ad nauseam: reduce the need to travel by evening out activity and not having the vast majority of economic activity taking place in just a small area of Central London (and yes, that's what needs to happen first; it's a case of redirecting investment, and it needs to be in the London Plan). Even were that to happen, the (Boris Johnson-'era') threat of the Roads Task Force-style massive expansion of motor traffic capacity around the perimeter needs to be fought off.

    Anyway, that's getting very far away from what we're talking about.

  • I don't think you have... how is it going to improve conditions? Given that there is no headline about how actual tfl modelling will be adjusted it's just yet more Khan hot air and I'm not impressed.

  • Thanks, Oliver - I look forward to the book! For the moment, is there perhaps anything available in German or Dutch? I was aware of the Oldenziel, but haven't got round to tracking down a copy; will have to see if my OH can get it through her institutional library. Same for the Forrester, as well; I've not read any of his books, and mainly know him by reputation as the segregated cycle infrastructure enthusiast's kryptonite...

    Unfortunately I don't have a local local cycling campaign, but I should really try and get involved with some of the other ones in the West Midlands - will have a look online to see about meetings etc.

  • As for junction design (in the peak hour, and along the various routes into Central London), you won't get a different approach until network-wide problems are addressed, as I keep banging on ad nauseam: reduce the need to travel by evening out activity and not having the vast majority of economic activity taking place in just a small area of Central London

    That just ends up with people living in A and working in B, and vice versa, all committing through C which used to be a nice village but which is now in the way of a shiny new bypass. For example look at cities like Houston. Because economic activity is spread out it is very easy to build direct road links over huge distances - nothing valuable is in the way.

    By comparison, extreme centralisation:

    • has economic benefits (specialisation)
    • drives up land value and density making it too expensive to build roads compared to high capacity public transit
    • allows people to select where they irrationally want to live and still get to the center of economic activity without using a car
    • allows people to meet to their friends (who have probably moved to another district) without relying on cars as they can meet in the middle or connect public transport there

    High rise cities should also benefit cycling because everything is closer together.

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Green Man Authority

Posted by Avatar for The_Seldom_Killer @The_Seldom_Killer

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