[sustran] Re: Bombay request for information

[SUSTRAN Resource Centre]

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). 

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..... 

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. 
PLEASE NOTE NEW 8 DIGIT TELEPHONE/FAX NUMBER

Dr A. Rahman Paul BARTER
Sustainable Transport Action Network for Asia and the Pacific (SUSTRAN)
P.O. Box 11501,  Kuala Lumpur 50748, Malaysia.
TEL/FAX: +60 3 2274 2590
E-mail: sustran at po.jaring.my
(old address tkpb at barter.pc.my has been cancelled)
Web: http://www.geocities.com/RainForest/Canopy/2853/

The SUSTRAN network promotes and popularises 
people-centred, equitable and sustainable transport 
with a focus on Asia and the Pacific.