CityCyclingEdinburgh Forum » Infrastructure

The scandal of the 30mph buses

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  1. Instography
    Member

    Sorry. Let's say there are only three speeds available - 10mph, 20mph and 30mph. You measure before speeds and find that 5% of people drive at 10mph, 90% drive at 20mph and 5% drive at 30mph. The average speed is 20mph.

    You measure after speeds and find that 5% of people drive at 10mph and 95% drive at 20mph. The average speed is 19.5mph. It looks like you've achieved nothing much - a reduction of 0.5mph. Oh how the opponents laugh.

    But what matters is that the reduction in the mean is achieved by reducing the speeds of those whose before speed is above the mean. It might only have affected 5% of drivers but it affected all of the ones that matter.

    Posted 12 years ago #

  2. wingpig
    Member

    When people generally don't read entire manifestoes before choosing for whom to vote, they're going to choose those whose broad-brush principles/politics/trumpeted policies are least unfavourably aligned to their ideals.

    Who was it collected/summarised the various MSP-candidates' cyclist-pertinent policies prior to the Scottish Parliament elections? That was sort of helpful, but some of the paragraphs quoted looked much less decisive/meaningful when taken in the context of the whole manifesto (where "we should blah blah cycle blah" was then often preceded by "we ABSOLUTELY MUST blah blah something else blah", making the quoted bit look very tacked-on and soppish).

    Posted 12 years ago #

  3. Morningsider
    Member

    Instography - nicely put. I think such an effect is quite common when you reduce speed limits. People who speed are still quite likely to do so - however, they are still likely to go slower in a 20mph zone than a 30mph zone - even if they are still exceeding the limit. I have seen research to this effect - but don't have the time to track it down just now.

    Posted 12 years ago #

  4. amir
    Member

    That makes sense. Instead of the mean, it would make sense to calculate the proportion of drivers exceeding a particular "safe" speed.

    There is a duty on policiticians to use statistics properly and not in a misleading fashion.

    Posted 12 years ago #

  5. wingpig
    Member

    Do those little solar-powered speed-stating LED panels (like the one on Maybury Road) ever record the speeds they detect, particularly where the speeds detected are above the speed limit?

    Assuming that some speed-limit-breaking drivers are trying to stay in the window between the unreasonably-low-posted-limit and the higher speed-above-which-prosecution-would-be-likely-if-caught (whatever the modern equivalent to the anecdotal (([speed limit] * 1.1) + 2mph) is) then this also drops in the event of the posted speed limit dropping.

    Posted 12 years ago #

  6. Dave
    Member

    Instography - is that what is behind the 85th percentile speed reading that we get given? I've never quite grasped why that is used.

    Posted 12 years ago #

  7. chdot
    Admin

    @ anth "Count me in for helping with that."

    Thanks, think it could be fun...

    @ Instography if the apology was for me, no need. Just saying I have forgotten the differences between mean and median etc.

    JUST GLAD you haven't and are thinking (usefully) about this!

    @ Wingpig "they're going to choose those whose broad-brush principles/politics/trumpeted policies are least unfavourably aligned to their ideals"

    Sounds about right. Party manifestos 'disappear' when in office - 'oh we didn't realise the last lot had left things this bad', 'well it's all a question of priorities - we won't be able to do ALL the things in the first 4/5 years (so please vote for us again)'.

    Asking individuals to tick a few boxes means a slightly higher degree of 'commitment'.

    Presumably the views of Cllr. Barry aren't entirely Party policy. But some voters would have appreciated an insight before they voted for him - and before next year's election...

    @ Morningsider "I have seen research to this effect - but don't have the time to track it down just now.'

    We can wait!

    Posted 12 years ago #

  8. crowriver
    Member

    @wingpig Who was it collected/summarised the various MSP-candidates' cyclist-pertinent policies prior to the Scottish Parliament elections?

    That would be Spokes.

    If anyone here is not yet a member, please consider joining. Spokes is the best organised, most useful lobby we have.

    Posted 12 years ago #

  9. Wilmington's Cow
    Member

    "Spokes is the best organised, most useful lobby we have."

    This is, sort of, one of the reasons I haven't joined (which may sound odd). I think Councillor Barry's derogatory reference to the 'cycle lobby' sums a lot of it up. The lobby is good, certainly, at raising issues and representing voices, but I think it can also create a 'target' of sorts to fight back against - a lot of good ideas or arguments may be ignored as they may simply seen as being 'lobbying'.

    Whereas an upswell of individual public opinion has the disadvantage of being disparate and perhaps contradictory, but comes across as the 'ordinary' people. And in our current set-up I think 'ordinary' outranks 'lobby' for our councillors and MPs/MSPs because 'ordinary' votes, whereas 'lobby' is a blob that irritates and politicians can't see the people behind.

    Or something. That might not make sense.

    Plus I've disagreed with various Spokes policies in the past - although I guess being a member would give a better voice to discuss that. Hmmmm.

    Posted 12 years ago #

  10. Instography
    Member

    @Dave

    As I understand it, the 85th percentile speed starts from the assumption that left to their own devices and in circumstances where they can do what they want, people will adopted a speed that they consider safe. This is the speed that is implied by the road and its surroundings. If you want to set a speed limit that will secure automatic compliance, the 85th percentile will get you close to that. It doesn't mean that speeds above are necessarily unsafe but you'll get mass compliance with a limit based on the 85th percentile because that's what most people will do anyway.

    It leads to the idea that roads explain themselves to drivers and where there is widespread speeding the problem most probably lies in the engineering of the road rather than the drivers. Conversely, limits that appear too low to the bulk of drivers will be routinely ignored. The important thing is that it starts by assuming that most people are sensible.

    The classic Edinburgh example is the road from Western Corner past the zoo. It's at least a 40mph road i.e. its width, straights and sweeping curves, its lack of parked cars and its four lanes all say "go!" and before the camera and now at points either side of the camera, it is probably in practice a 40mph road when traffic volumes allow it. The 30mph limit is 'wrong' for the road and so needs to be enforced by a camera.

    Posted 12 years ago #

  11. Morningsider
    Member

    Anth - I think politicians need to hear from both groups like SPOKES and individuals. SPOKES, which is probably Scotland's best entirely voluntary campaign group, does lots of the "heavy lifting" - annual funding survey, cycle counts etc. which provide a sound evidence base for lobbying. Individuals add weight to this and provide a view from outside the lobbying field - which is also valued by politicians.

    Posted 12 years ago #

  12. crowriver
    Member

    @ anth - I can't help but notice that motorists have their own lobby groups (eg. AA, RAC Foundation, etc.) as do road haulage operators/drivers. They are not only listened to by politicians, they are quoted incessantly by the media spouting off on various issues.

    The more members Spokes has, the more representative the cycle lobby is seen to be, and therefore politicians have to listen. Simples.

    Posted 12 years ago #

  13. chdot
    Admin

    "and therefore politicians have to listen"

    If only life was so simple.

    "Fears over pavement cyclists"

    Posted 12 years ago #

  14. Wilmington's Cow
    Member

    @crowriver - absolutely, but as has been discussed before driving is 'establishment', an outgroup lobby group is something entirely different. Think about the public/media representation of the AA and RAC (knights of the road, legitimate concerns over petrol prices etc) compared to, say, Spokes and Friends of the Earth (bearded, sandled, tofu-eating hippies).

    Like I say, I've swithered for a wee while about Spokes, I'll swither some more. :)

    Posted 12 years ago #

  15. Wilmington's Cow
    Member

    Sorry, just realised I'm out tonight, so it will be Thursday for my more informed soapboxery.

    Posted 12 years ago #

  16. chdot
    Admin

    "Sorry, just realised I'm out tonight"

    Sorry, can't wait.

    .

    Oh well all right then...

    Posted 12 years ago #

  17. Klaxon
    Member

    I'm glad that by being deliberately brash with my first post I've pulled the discussion back towards why 20 limits are/are not a good thing as opposed to how awesome our counsellors are. I'm not keen on the way politicians work however it's for another time :-)

    Some time tomorrow when I am feeling less fatigued I'll take a good look over the large and comprehensive report on Portsmouth that Morningsider has kindly linked. Until I do so, I shan't pass any farther judgement on that specific matter.

    Instography sums up quite well exactly my feelings on speed, Glasgow Road being a good example. I'd like to think that from a driver's point of view the limit between approx the Murrayfield Hotel and the junction for Pinkhill could be 40 - lowered to 30 through Costorphine and probably even 20 would be appropriate in the 'town centre' from where the bus lane disappears going west. That's what seems safe and sensible given the current layout. I've mellowed recently however it used to frustrate me enormously driving or being driven on the clear section at 30.

    An alternative would be to redevelop the street as a European style bike corridor, with a wide single lane of traffic to allow cars to pass stationary buses and pavements widened to have unidirectional cycle lanes. To that end, Balgreen Road would likely need signalised or an innovative solution to give westbound cyclists correct priority. If this were introduced, 30 for the length would seem normal.

    So that draws me back to Newington. For the population density along Nicolson and Clerk St, narrow pavements pervade as do the part time bus lanes. The road experience is poor for drivers, cyclists and pedestrians. Lowering the limit to 20 and doing nothing more wouldn't seem to me to assist anybody in their journey. The daytime speed is probably close or lower than 20 anyway.

    Again I would support slower posted limits if the road were narrowed to a wide single lane and segregated cycle paths were introduced. However now I'm the one in a dreamy soapbox world, I've just proposed two flagship public realm projects comprising a total of 3 miles of pavement reconstruction. But just zoom in on this wonder that is 4.5 miles of cycle bliss in Berlin. The number of lanes for traffic is irrelevant, Edinburgh wasn't bombed to the ground in the 40s. There's never going to be more than a single lane of effective traffic over the bridges. So why not share the space better? :-)

    Posted 12 years ago #

  18. Instography
    Member

    Klaxon says:

    Lowering the limit to 20 and doing nothing more wouldn't seem to me to assist anybody in their journey. The daytime speed is probably close or lower than 20 anyway.

    But Klaxon, the argument that applies to Glasgow Road also applies to Newington Road. If the layout of Newington Road, its pedestrian traffic, parking and traffic volume is leading to an average speed (or an 85th percentile speed) of around 20mph in normal conditions then that suggests that a limit of 20mph would be entirely appropriate. Such a limit could only be a restriction on people who would try to exceed the speed that the typical driver would voluntarily choose.

    Posted 12 years ago #

  19. chdot
    Admin

    As I said earlier there's a by-election soon.

    "
    melaniemain:

    City Centre By-election canvassing.  Great to hear that though voters disillusioned with the ‘main’ parties say they will still vote. #edcc

    Original Tweet: http://twitter.com/melaniemain/status/98860337020936192

    "

    SO -

    Is that Green, independent or just voters telling canvassers what they want to hear?

    Posted 12 years ago #

  20. Klaxon
    Member

    Instaography, I'm referring above specifically to the section between South Bridge and the jn with Salisbury Road. The majority of which, having just checked, isn't even in the consultation. The outer length of Newington Road is a wide boulevard. Grange Road has in my experience only sporadic on street parking, light traffic volume and is wide. I wouldn't be surprised if speeding is common on each with the limit set at 30.

    The 20 area seems sensible as proposed. Imagine if between Cameron Toll and Blockbuster you had a 20 limit... then that went up to 30 just as you reach the busiest bit of Southside!

    In your OP referring to bus speeds Dave, have you included time spent stationary in the time spent at <20mph?

    Posted 12 years ago #

  21. Kirst
    Member

    Yes, there's a by-election soon, and a hustings has been organised at the City Chambers on Monday 15th August 6-8pm. All welcome.

    Posted 12 years ago #

  22. Dave
    Member

    In your OP referring to bus speeds Dave, have you included time spent stationary in the time spent at <20mph?

    No. There was a further 02:40 spent completely stationary on the trip, so overall it took:

    14:45 for 3.1 miles (true average: 12.6mph)
    12:06 in motion (moving average: 15.4mph)
    02:43 above 20mph (saving 24 seconds over 20mph)

    I suppose it's germane that the 24 seconds "lost" would largely have been recovered in reduced waiting time at several sets of lights. I wasn't sure about this point because obviously you will sometimes miss the lights if you're even a split second slower, although everybody's main recollection of being in Edinburgh traffic is waiting at reds regardless.

    The point put to the committee was based on the length of time spent above 20mph though (which is all that would change with a change in the posted limit). A bus in a stop isn't really influenced by the speed of passing traffic (I suppose they'd be able to get out more easily in a slower limit).

    Posted 12 years ago #

  23. amir
    Member

    Klaxon - with respect to the A8 (in town), there is room for different opinions here. Whilst this is a wide main route into town, it is still a residential area. Walking alongside this road is not a pleasant experience due the noise of the traffic. Crossing the road is difficult other than at the widely spaced crossing points. It is difficult to get the balance right, and as a car driver I can understand the frustrations of having speed restricted.

    Posted 12 years ago #

  24. Klaxon
    Member

    Dave, if you want to come back at Lothian then point out that early in the morning (pre 7am) their buses cruise at 20mph with clear roads in front of them, and still sit at bus stops because they're ahead of schedule!

    Posted 12 years ago #

  25. Instography
    Member

    Is it possible to see the submissions made by LRT and the Police, partly to take issue with them directly and partly to question the Council's acceptance of them.

    Posted 12 years ago #

  26. Dave
    Member

    The consultation response is linked up thread (or on one of the other topics about this in Infrastructure), I think.

    Posted 12 years ago #

  27. ruggtomcat
    Member

    @klaxon the road in berlin you linked too was made long before the city was bombed and was originally a dyke built through a swamp so the king could get to Potsdam (was my local history lesson last night).

    Posted 12 years ago #

  28. Wilmington's Cow
    Member

    I am planning on coming back to this. Honest!

    Posted 12 years ago #

  29. chdot
    Admin

    "I am planning on coming back to this. Honest!"

    It's alright - we'll let you turn it into a major .citycycling investigation...

    Posted 12 years ago #

  30. chdot
    Admin

    And have a look at http://citycyclingedinburgh.info/bbpress/topic.php?id=3577 - seems to have raised some controversies!

    Posted 12 years ago #

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