From: adrian@ntmtv.UUCP (Adrian Brandt)
Subject: Re: Cost of transit systems vs highways
Organization: Northern Telecom Inc, Mountain View, CA
Date: Fri, 28 Aug 1992 22:28:26 GMT

In article <1992Aug28.175138.23709@s1.gov>, lip@s1.gov (Loren I. Petrich) writes:
|> In article <9208281421.AA05078@asia.fai.com> vaughnw@asia.fai.com (Vaughn Wolffe) writes:
|> >Bay Bridge, it carries over 250,000 vehicles a day at an average 
|> >occupancy of 1.13 per vehicle. Considerably less than half use BART.
|> 
|> 	250,000 vehicles/day??? That strikes me as a bit much.
|> 
|> 	It's a ten-lane bridge, and if one vehicle/s managed to pass
|> through each lane, then they would take 7 hours for all of them to
|> make it.

The max sustained lane throughput I've heard thrown around a lot is 1,800
to 2,000 cars/hr., or a car every 1.8 to 2 seconds.  A 10-lane bridge
(5 on each deck) would have to run all 10 lanes at full bore (maximum
throughput) for 12.5 to 13.9 hours to do this.  Since there are 24 hours
in a day, it seems the 250,000 vehicle per day figure is *possible*.



|> 	How well does CowTrain, er, CalTrain work???
|> 
|> 	It is much _less_ successful than BART in getting people out
|> of their cars.

No less succussful than BART would be with the *same* frequencies on
the *same* tracks.  Based on various average speed calculations I have
done for BART lines that are similar to the CalTrain line, I'm certain
BART's average speeds would be only a few mph better.



|> 	And your proposed BART clone can be had only at the expense of
|> buying _lots_ of extra rolling stock, to say nothing about upgrading
|> the stations to make them look like BART-clone stations.

Loren, please explain in detail why "_lots_ of extra rolling stock
would be necessary.  Sure, *some* would be needed, but not lots.  Once
equipment reaches the end of the line it can be run back the other
way.  Once you have enough equipment to fill the whole line at a certain
"train density" (or headway), you don't need much more for spares, etc.

For example, I calculated that to fill the roughly 50-mile SF-SJ part of
the line with trains spaced at 15 min intervals in both directions at
a 40 mph average speed (a train every 10 miles on each of two tracks),
you'd only need 10 trains.  CalTrain already has 20 locos and 73 cars.
This means you could have 10 spare locos being serviced or standing
by, while 10 were out on the line each pulling 6 car trains.  Each
one of these trains would have seating for about 870 people, so you
get a people moving capacity of 3,480 people per hour per direction,
for a total of almost 7,000 per hour.  That's roughly equivalent to a
four lane freeway's max throughput.


|> 	What's this grudge against BART that you seem to have?

I won't speak for Vaughn, but I think it's s too expensive and too
politicized for starters.  After that, I'd say it isn't compatible
with much of anything and if it ever (god forbid) actually replaced
CalTrain's tracks (I doubt it), you'd lose the ability to bring
other trains like a future LA-SF TGV-style high speed rail service,
or Amtrak passenger trains, or freights down the peninsula and into
or near the city of SF and its airport.


-- 

Adrian Brandt (415) 940-2379
UUCP: ...!ames!ntmtv!adrian
ARPA: ntmtv!adrian@ames.arc.nasa.gov