From: adrian@ntmtv.UUCP (Adrian Brandt)
Subject: Re: Alliance for a Paving Moratorium (Alert)
Organization: Northern Telecom Inc, Mountain View, CA
Date: Tue, 5 Jan 1993 19:18:26 GMT

In article <1993Jan5.004707.15935@pbhya.PacBell.COM>, whheydt@pbhya.PacBell.COM (Wilson Heydt) writes:
|> Now let's *both* look at reality.

Okay, but I thought I already was.

|> You've assumed two things--first that trains *will* be run at the
|> kind of headways you're talking about.

Yes, *and* I assumed the freeway lane would be running at maximum
practical throughput for an *entire* hour (no congestion, no big gaps
between cars, optimum speed and a generous AVR of 1.11).

|> While you are (no doubt) correct that CalTrain (per your example)
|> *can* run 5 minute or less headways--do they?

Nope, but we're talking about comparing the practical carrying capacity
of a rail line to a freeway.

|> I seem to recall complaints about 2 *hour* headways at some times of
|> the day...

From 5 am to 8 pm, the maximum headways are the hourly midday trains.
Some folks like to vaguely (and misleadingly) claim "CalTrain still has
two-hour headways" because there is a 2 hour gap between the 8 pm and
10 pm trains.  I suppose if for some reason there was a 2 am train, the
same folks would say CalTrain had 4 hour headways...  Sheesh.


|> The second issue is that, while you have cited *average* occupancy for
|> cars, you've cited full seat occupancy for the trains.  If I took the
|> daily ridership on CalTrain and divided by the number of trains--the
|> figures for trains would be lower, and I assumed that every car seat
|> is full (say--an average of 5 per car?) the freeway value would be
|> much higher.

While assuming full seat occupancy for the train is being somewhat
optomistic (to say the least!), it is important to remember that the
fudamental nature of auto and train seat occupancy are very different.
Trains (for the purposes of this discussion, anyway) are open to the
public and run on fixed (hence predictable) schedules along a known
route.  The idea is to allow and encourage people to come and fill
them up.  Autos, as you well know, are quite different.  They are
typically owned by one person who typically exercises total control
over how and when it is used.  As many statistics and real-world
observations will show, auto owners generally don't like to carpool.
So people don't/won't share an auto much.  Besides, it generally not
easy to do, even if you want to.  So forget 5(!) per car.  I doubt
we'll ever even see 2 per car (average, of course).


|> In addition, the need to run trains back to the start point empty in
|> many real-world scenarios ties up rolling stock, uses energy, wastes
|> crew time and has to be accounted for in the headways.

Oh, really?  Since we were talking about CalTrain, why don't you describe
this in a little more detail for me--especially the part about how it
"has to be accounted for in the headways".  Be as specific as you can.


|> At least with the car--the don't 'dead head' half the time.

Well, it seems that since cars typically have no passengers and only
have *the* crew-member aboard, that they're "dead-heading" damn near
100% of the time :-)  Or to view it another way, we could say the
typical SOV keeps it's single "passenger" so busy doing the "crewing",
that it renders him/her a dead head for the duration of the trip...


|> (Yes--I know that CalTrain simply stores many of the trains at one
|> end of the line for long periods of time--but that's the equivalent
|> of parking cars which Mr. Vandeman deplores so often--and much more
|> valuable cars--each--at that.)

Yeah, all vehicles should avoid parking at all cost.  Keep 'em all
moving all the time!  Seriously though, many of us *do* deplore that
so much CalTrain equipment is "parked" when it could be making more
runs to help fill out the CalTrain schedule.  (Lack of equipment is
NOT the problem in reducing CalTrain headways to a half-hour maximum
ALL day long...  Lack of demand is NOT the problem either...  Grade
crossings and safety aren't it either...  It's politics!)

-- 

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