From: lip@s1.gov (Loren I. Petrich)
Subject: Re: Is car pooling for real? (was Re: Are bikes really less polluting?)
Organization: LLNL
Date: Thu, 23 Jul 1992 00:45:37 GMT

In article <Brsryo.BxL@watserv1.waterloo.edu> rlbell@babbage.waterloo.edu (Richard Bell) writes:
>In article <4xdmd6h@dixie.com> jgd@dixie.com (John De Armond) writes:

::Cheaper is debatable.  Safer, surely not.  I'd like to see you justify
::your claim of "environmentally friendlier", whatever that means.

:Mass transit may, or may not, be cheaper (it is for me but your mileage
:may vary), but it is definately safer.  I was in a GM bus that was rear ended
:by a compact.  The bus had stopped to let off some passengers.  There was a
:barley detectable thump, and the confused passengers and I watched the driver
:exit the vehicle, instead pulling into traffic.  People outside staring at 
:the bus clued us in to what had happened.  The car had its right front crushed
:in by a collision none of us felt.  10 tonne (metric) buses winn collisions
:with almost any object not set firmly in concrete, they are driven by people
:who have had rigorous training (the only license harder to get than a bus
:drivers license is a schoolbus drivers' license [in ontario]).

	I once looked up some accident figures, and buses and trains
-- and even commercial airplanes -- did a lot better than cars in
fatality and injury rate per passenger per distance traveled, by at
least a factor of 10.

	I don't have figures on many mass-transit systems but I can
cite one example: there has been only one death due to an accident in
the BART system in all its 20 years of operation, and that was of a
fireman who was putting out a train fire. There have been no passenger
deaths in all that time; in that fire (the worst BART accident ever),
some passengers did have to be treated for smoke inhalation. Taking
the annual highway death rate and extrapolating it to BART's
ridership, I estimate that 200-400 people would have died if BART was
as safe as our highways.

	Furthermore, BART survived the Loma Prieta earthquake without
any serious damage, while there was some serious highway damage -- the
collapse of much of the West Oakland segment of I-880, the fall of one
of the spans of the Bay Bridge, and some damage to the Embarcadero
Freeway. Now which is more earthquake-safe?

	Intercity trains? On two modern system, the Japanese Bullet
Trains and the French TGV, the passenger death toll has been VERY
small, in both cases, due to "outside" causes -- for the Bullet
Trains, a truck falling off of a bridge, and for the TGV, the
explosion of a terrorist bomb.

:"Environmentally friendlier", a bus can easily carry 40 people (and if I
:were shorter, I might even say comfortably) a non-carpooling vehicle seats
:one.  Compare one bus versus forty cars: unless they are all chevy sprints,
:or worse, they use more materials to build, collectively burn more fuel than
:the bus, and definitely take up more space if not recycled.  I do not know
:if a bus lasts longer than a car or not.

	I _would_ like to point out a number of things that work
against buses in practice.

	First of all, a lot of times, local buses are simply not very
heavily used. This is an inefficiency comparable to a car carrying
only one person.

	This inefficiency holds up also for a bus that picks up or
drops off passengers along a route, no matter how full it is when
finishing or starting. However, this inefficiency is reduced if the
bus is doing express service, traveling a relatively long distance
without passengers either getting on or getting off.

	Second, buses have to be driven from and to their parking lots
when they go in or out of service.

	Third, buses often have to do a lot of stopping and starting,
in addition to stopping for traffic signals.

	Fourth, when waiting for some scheduled departure time, buses'
engines are often left on.

	These inefficiencies leave the average city bus not too much
better than a car.

	The first, second, and third of these are also typical of rail
transit systems, though the first can be reduced by having yards at
the ends of lines, as is the case for BART.

	The fourth inefficiency can be eliminated by using electricity
as the motive power; the bus draws power only when it is moving.
Electric buses draw their power from overhead cables, like a trolley
does. Of rail systems, all except some commuter systems are electric,
and these also get rid of inefficiency #4.

	Electric cars have not been very practical, due to the low
power density of typical batteries, but improved batteries may change
that situation. Improved batteries would also allow electric buses to
travel away from overhead lines; easily rechargeable ones could be
recharged if the bus is currently traveling under overhead lines.

	The third inefficiency can be reduced considerably if a good
means of temporary energy storage could be developed; a vehicle would
use dynamic braking, where a motor acts like a generator, the electric
energy would somehow be stored, and this stored energy would be tapped
for re-acceleration. Flywheels are one proposed system for performing
this storage, though I don't know how well-developed they are.

/Loren
Newsgroups: sci.environment,sci.geo.meteorology,sci.skeptic