3[wtpp] Bus lanes & Moore's Law revisited
- Jan 8, 2000I 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?
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.
ecopl@n ___ technology, economy, society ___
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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
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
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
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
1 McFarlane Street, Wellington 6001, New Zealand
Phone + 64 4 971 5549