[sustran] Re: Bombay request for information

[Eric Bruun]

I have a few additional comments below. Eric Bruun


On Mon, 27 Sep 1999, SUSTRAN Resource Centre wrote:

> At 19:22 23/09/99 +0530, you wrote:
> >Secondly do you know what is the ideal car to road ratio.  Is there any
> measure for Bombay?
> 
> Sorry, there is no "ideal" ratio of numbers of vehicles versus road length.
> There are too many complicating factors (lane kilometres would be better
> than road km, arterial capacity is more relevant than small streets, and
> traffic mix, traffic management, etc.... all make a difference). 
> 
 Also, vehicle OWNERSHIP is not a reliable method of determining vehicle
use. Off the top of my head I think Germany has between 500 and 600
vehicles per 1000 citizens whild the US has about 700, yet the 
annual urban vehicle-kilometers travelled in the US is twice as 
high. Just because people own cars doesn't mean that they use them
for every trip.

> There is also a danger from focusing on vehicle to roads ratios. The danger
> is that some people will conclude that the only obvious solution is to
> build more and more roads as quickly as possible. 
> 
> Having said that, let's look briefly at some simple numbers on this issue.
> Below are data for 1990. The first column is total vehicles per km of road
> (including local streets) for the whole metropolitan area. These numbers
> are derived from the Kenworthy, Laube, et al. data set (the 1990 update of
> the Newman and Kenworthy data set). The second column is passenger
> car-equivalent units (PCU) per km of road. They are based on the same data
> set's raw numbers and using some simple assumptions. 
> 
> By the way, Passenger Car-equivalent Units (PCUs) are a way to take some
> account of the fact that differnt kinds of vehicles use different amount of
> road space (e.g. in this case for argument's sake I just used a very very
> simple assumption that 1 motorcycle = half a pcu, 1 car = 1 pcu and all
> other vehicles = 1.5 pcus). 
> 
> I have dropped most of the cities from the list, leaving only a few to
> comment on, including all of the cities which had high numbers of vehicles
> per length of road. 
> 
> 	Vehicles/km of road		pcu/km of road
> 		
> Perth		63			68
> Canberra	61			64
> Phoenix	78			81
> ...
> Tokyo		195			215
> ...
> Munich		295			299
> ...
> Jakarta	371			306
> Hong Kong	284			333
> Surabaya	618			433
> Paris		456			? (>~460)
> Bangkok	538			499
> 
> Unfortunately this little exercise suggests that these ratios are NOT
> particularly useful, although they are not totally meaningless either.  
> 
> Cities with very low ratios do indeed have very free-flowing traffic. And,
> of the 5 cities with the highest pcu per road ratios, 4 are indeed
> notoriously congested throughout the day. BUT Surabaya is not particularly
> congested even though it's high ratios suggest that it should be.  Also I
> have heard that Tokyo's arterial roads and expressways are clogged
> throughout the day. But Tokyo's ratios were NOT up among the high figures.
> As I said above, there are many other factors..... 
> 
  The space consumption for parking gets huge when cities become
based on autos. This, in turn, starts to ruin the pedestrian atmosphere
and increase travel distances for the non-motorized modes. Then it
causes even more people to want to drive. Just look at what has
happened to most US cities. One can not walk or bicycle safely 
even if one would prefer it.


> NEVERTHELESS, maybe we could use these numbers as a very rough "RULE OF
> THUMB" to suggest that a figure of 300 or 400 vehicles per km of road means
> a city is probably heading for big trouble from congestion, especially if
> vehicle numbers are still rising quickly and especially if there are not
> many motorcycles. You will need some recent data on roads and vehicle
> numbers for Bombay (careful that the roads and the vehicle data are BOTH
> for the SAME area which should be the whole metropolitan area if possible -
> Greater Bombay say). You could also try to look at trends to see how soon
> Bombay will reach these "high" ratios.
>   
> 
> >Also in Bombay alot of the public transport like taxis, autorickshaws and
> buses cause a great deal of air pollution.  This needs to be regulated.
> How do we do that?
> 
> A very big question. There is lots of literature on this. You could start
> by consulting the World Bank's Urbair document that Walter Hook recommended
> to you. I am sure it would have a few simple suggestions. Sometimes a
> simple requirement for a yearly vehicle inspection for all commercial
> vehicles brings a substantial pollution reduction, provided corruption is
> not too rampant among those responsible for inspecting the vehicles. I
> don't have references handy on this issue.. any experts on this on
> sustran-discuss??
> 
> >What do you mean by gridlock?
> 
> Gridlock is a colloquial way to say "bad traffic congestion". 
> 
> I hope this helps. 
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> 
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> Sustainable Transport Action Network for Asia and the Pacific (SUSTRAN)
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