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3[wtpp] Bus lanes & Moore's Law revisited

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  • eric.britton@ecoplan.org
    Jan 8, 2000
      I guess that since Kerry Wood posted this here (and for those who may not
      have Kerry's notes in front of you I have (exceptionally) logged in the
      whole thing below) it's cause comments and perhaps useful ideas and
      reflections are in order. Let me have a shot, but first a word from our

      Kerry, it is a splendid thing indeed to see so much good sense making its
      way into halls of transport counsel (and of course better yet when they make
      their way into transport practice). For a long time, these were for most
      cities marginal ideas, so far out of the mainstream of what was perceived to
      be possible and desirable that they never even began to get a hearing. How
      rewarding it is, therefore, after a couple of decades to see such ideas
      starting to shape the mainstream. We still are a bit of a way from that
      accomplishment of course, but it strikes me that we are now beginning to be
      well on our way. All it takes is more work, more imagination and more
      examples on the ground which are just so extremely striking that they can no
      longer be denied (thanks, Zurich, Curitiba and eventually hundreds of other
      cities, mainly in Europe, which are starting to change the rules and our
      perceptions of what works and what most evidently does not).

      Observations on the draft:

      1. "...speeding up ALL traffic by making public transport faster and more
      I am afraid that a tremble at the hypothesis so stated, as I am sure you do.
      But permit me to carry on for a moment on this. The advantage of putting it
      this way of course is that it pre-empts the cars-first crowd, by suggesting
      to them that what's good for the system will also be good for them. That may
      be cagey politics but it's dangerous and I think ultimately quite wrong.
      Dangerous, because it may give them more rope to go out and make THEIR
      traffic hustle along even faster, which of course gives all the other modes
      the short end of the stick... once again. And wrong of course because as
      Wood and others have abundantly pointed out, the only way to make any sense
      out of the system is to render the environment steadily, each day a little
      more, somewhere between unfriendly and inimical to the good old private car.
      In the sustainable city, you will see the odd solo-driver car here and there
      during the day, just like you see the old Spotted Owl, and it will set you
      to wondering "Whatever is THAT doing HERE?"

      2. "...raise bus lanes.."
      Ouch. This strikes me like a first-generation "solution", for which one can
      understand all the reasons and thinking behind it but which one still needs
      to pop right into the dustbin. This is not to toss out the problem of lane
      clearing, which I think can be solved (later), but it is to suggest that
      anything more than a thick stripe of plastic paint or whatever is both
      potentially dangerous and unfriendly to others out there on the street.
      They also tend to be quite ugly, even threatening, and I do think that we
      already have enough ugly and threatening things in most of our cities not to
      consciously opt for more.

      3. "...bus gate..."
      broadly as above.

      To conclude: Bus lanes are a terrific way to start to organize thinking and
      practice on sustainable transport in cities, because they are concrete, they
      now come complete with a growing number of convincing demonstration sites
      (meaning that you can just haul your politicos and traffic mavens over to a
      selection of places so they can see for themselves.... perchance to dream),
      because they do not require enormous gobs of hard earned taxpayer dollars,
      and because it's something that any city can start to move toward, say,
      beginning tomorrow morning. All you have to do is find a way to sell the
      idea, and then, with proper preparation, it should simply sell itself.

      A final wrinkle and observation: Think of bus lanes and all that goes with
      them (including the SurfaceMetro concept, pace Curitiba) as today being
      still in theory and in practice in very early stages of their evolution.
      Say, the on-street equivalent of an Apple II on your desk in 1977 and just
      about everyone who passes asks you why ever would you waste your time with
      that. Filing recipes?

      Conclusion: Let's get together and see if we can apply Moore's Law to
      transport in cities. Wouldn't you say that 18 months is just about the
      right amount of time to demonstrate that we too can double and half? Might
      we think about that together too?

      Eric Britton

      P.S. If I can have the author's permission, we would like to post his
      completed article as the Essay of the Month on the @Access on the Web site
      at http://www.ecoplan.org/access . The idea is to encourage both
      distribution of leading edge thinking on these matters, as well as
      discussion. The author would be in good company, if you check it out - the
      present resident of that slot being Peter Drucker.

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      From Kerry Wood [kerry.wood@...] on 08/01/2000
      I am in the middle of a paper on speeding up ALL traffic by making public
      transport faster and more efficient. Here are some bits from it (sorry, it
      has diagrams which get messy on e-mail)

      ISTP data shows that cities with low car use have low overall transport
      costs. (I have used their figures for operating cost of non-freight

      For as long as the debate is about road building for cars, it is not so much
      about improving transport as about how quickly it will get worse.

      Huge figures for the cost of congestion are meaningless in a policy context
      because there is no prospect of realizing the savings: Mogridge (1997)
      refers to 'ghost city' traffic flows. They can also be used to support any
      option, and so cannot discriminate between options.

      It has been known since the Buchanan report (1963) that full motorisation is
      impracticable in a large city - especially if that city has a high density.

      Speeding up motor traffic is self-defeating in four ways:
      * If the car-carrying capacity of the road is increased, the cost curve for
      cars is flattened. The result is that some passengers switch from passenger
      transport to car use. More cars quickly offset the savings and costs return
      to their old level (the cost curve is very steep in congested traffic, so
      mode switching does not have to be on a large scale). However, passenger
      transport costs increase because there are fewer passengers: fares may rise,
      the operator may take off some services, or the service may even close.
      Higher costs encourage more passengers to switch to car use, so car costs
      rise until they reach the new passenger transport costs. When the
      readjustments are complete the point where the cost curves for passenger
      transport and cars cross is at a higher cost than before the capacity
      increase: the road 'improvement' has increased costs for everybody.
      * Capacity increase in an urban area simply releases suppressed demand.
      This accounts for the common observation, first made in the 1930s, that a
      new urban highway does not reduce traffic on the old route (SACTRA 1994).
      SACTRA's explanation is that new capacity induces new traffic on an
      important scale, which is not allowed for in most transport modelling.
      * Urban design effects. For example, good car mobility allows supermarkets
      to drive local stores out of business, frustrating accessibility and needing
      more mobility to meet the demand created
      * Buses are slowed down in four ways. They have greater difficulty in
      re-entering a faster traffic stream after a stop, or in crossing fast
      traffic to reach a right turn lane; they consistently miss traffic lights
      set to give motor traffic a 'green wave' through several junctions, because
      of the need to stop for passengers; they suffer long delays at traffic
      lights set to maximise traffic capacity by using long phases; and they often
      follow a more circuitous route to pick up passengers.

      Suppressed demand is usually a smaller economic problem than excess demand.
      SACTRA (1999) studied the economic impacts of reducing traffic, and
      "The external costs arising from road transport provide a rationale for
      traffic reduction insofar as it arises from the alignment of marginal
      benefit with marginal social cost. (7.125)
      "..a more efficient allocation of resources might result from well?targeted
      reduction measures. There is a strong case for correcting market failure
      since marginal social costs appear to exceed marginal benefit on many
      journeys." (7.126)

      Reducing capacity also has little effect on speeds. Cairns and her
      co-workers (1998) found 47 traffic reduction schemes where usable data was
      available, with an average area-wide reduction of 25% of the capacity of the
      altered streets. Crucially, they could not find any example of capacity
      reduction causing 'traffic chaos,' beyond a short adjustment period (it will
      be alright by Friday), even when there were catastrophic reductions due to

      Road building making the situation worse is called the Downs-Thomson effect.
      Thomson (1977) describes the process like this:
      "If the decision to use public or private transport is left to the free
      choice of the individual commuter, an equilibrium will be reached in which
      the overall attractiveness of the two systems is about equal, because if one
      is faster, cheaper and more agreeable than the other there will be a shift
      of passengers to it, rendering it more crowded while the other becomes less
      so, until a position is reached where no?one on either system thinks there
      is any advantage in changing to the other...
      "Hence we derive one of the golden rules of urban transport: the quality of
      peak?hour travel by car tends to equal that of public transport."

      Studies of door-to-door travel speeds in several cities show that speeds on
      public and private transport are remarkably similar, and studies of
      household travel surveys show that about 15% of commuter cars are not used
      every day: there is mode switching going on.

      Zurich is one of several European cities that have pursued a policy of
      improving public transport for some years. It is a particularly interesting
      example because excellent results have been achieved at comparatively low
      cost, with few subways and some surprisingly old vehicles. The head of VBZ,
      the Zurich transport authority, claims:
      "The only way to reduce traffic problems is to promote public transport

      "Our strategy has been promoting public transport, reducing non-essential
      car traffic, funneling traffic onto trunk roads, reducing parking provision
      and encouraging pedestrians and cyclists." (Heierli 1996)

      Cost/modal split diagrams (following Mogridge) show that speeding up
      passenger transport also speeds up cars EVEN IF SPACE IS TAKEN FROM CARS TO
      MAKE ROOM FOR PASSENGER TRANSPORT. This is what has been done in Zurich, as
      well as many other European cities. It seems to boost rather than depress
      the economy.

      ISTP data includes in-vehicle speeds for private and passenger transport for
      a range of cities, as well as the proportion of journeys to work by car.
      Plotting these gives a clear boundary line, which seems to represent the
      Downs-Thomson effect: all the cities quoted by Mogridge are on on close to
      this line.

      Mogridge (1997) mentions sample calculations suggesting that in central
      London average traffic speeds could be doubled by favouring passenger
      transport: clearly this would being major commercial benefits. Trucks have
      to be considered, but they do not necessarily need more road space - they
      are usually only about 10% of a traffic stream.

      A common assumption is that business people need car access, but what they
      really need is good access. Heierli (1996) says:
      "Zurich has... succeeded in giving its public transport operators the image
      of modern companies with a clear customer focus, which... results in a very
      positive image. The outcome of this is that there is no stigma attached to
      travelling by tram in Zurich; indeed, anyone who does not use the tram tends
      to be regarded as out of touch.
      "Our politicians make regular use of public transport (not just at election
      times) and leading figures from economic and academic life would not
      consider commuting in any other way."

      Buchanan, C (1963) Traffic in Towns. London: HMSO
      Cairns, S; Hass?Klau, C and Goodwin, P (1998) Traffic impact of highway
      capacity reductions: assessment of the evidence. London: Landor.
      Heierli, R (1996) European Lecture: Public transport in Zurich. Proc Instn
      Civil Engineers, Transport 117, November Mogridge, MJH (1997) The
      self?defeating nature of urban road capacity policy. Transport Policy 4 (1)
      pp 5?23 Thomson, JM (1977) Great cities and their traffic. London: Gollancz.
      Quoted in Mogridge (1997)

      I like the idea of running bus lanes in the 'wrong' direction to keep cars
      out of the lane. Thanks Lake.
      Another approach is to raise bus lanes about 80-120 mm above the general
      traffic lanes (or about 150 mm with a beveled kerb), so that motor vehicles
      can use them at low speed in emergency, but not just to save a few seconds.
      Brussels uses a thing like a painted broken line, but the 'paint' is
      concrete and 100 mm high.
      A good design for a 'bus gate' to keep other traffic out of a bus lane is a
      narrow section of road, between kerbs, with a level surface where the bus
      wheels go but a dip where the narrower car wheels go. It doesn't matter if
      the inner wheels on the back axle of the bus are unsupported. The dip can
      be enough to slow cars down, or deep enough to stop them, and a ridge (low
      enough to clear the bus differential) stops them from going over the dip too
      fast for their wheels to drop in. The trouble is that it is comparatively
      expensive, because the dip needs separate drainage.

      Kerry Wood MICE MIPENZ MCIT
      Transport Consultant
      1 McFarlane Street, Wellington 6001, New Zealand
      Phone + 64 4 971 5549