[Seth-Trips] Petition to keep Bart open late

Nick Moffitt nick at zork.net
Fri Nov 14 20:58:59 PST 2003

begin  Praveen Sinha  quotation:
> > 	They spend every minute of downtime on maintenance as it is!
> > The BART curfew is an unhappy necessity caused by design decisions
> > made in the 1960s.  To keep late-night service, they'd have to add
> Do you know what these design decisions were out of curiosity?

	The big one is the lack of any express or backup tracks.
Shutting down a section of rail shuts down the entire system, since
there's no way to route around it.  It's like having nothing but a
single two-lane road in your town: you have to wait until midnight to
fill in all the potholes.  There are actually NO SIDINGS whatsoever in
San Francisco: disabled trains have to limp to Daly City or Oakland
before they can be moved out of the way!

	The other is the all-seeing all-knowing computer control
system.  Take that down, and everyone's at a complete loss.  No train
can run without the thing.  A proper rail network has a backup system
that operates (albeit more slowly) as a collection of cellular automata
providing signals (two, actually -- proper rail signals tell you what
the NEXT light will be as well as the current one, hence "red over
red" for a full stop).

	Here's a pretty good page describing the classic English
distributed signaling system:


	And here's the one they use in the Tube trains:


	The Key Transit system had the ATP signals wired to an
override circuit in the power sources -- it was electrically
impossible to maintain velocity without sufficient headway!

	But BART has *NO SIGNALS AT ALL*!  Without the computer
control in the early super-broken days (1972), they had station agents
CALLING AHEAD ON THE TELEPHONE to see if the track was clear!

	Finally, they just didn't know how to be good consumers of
rails and rolling stock.  The rails need regular grinding, since
degradation causes "rail howl": irregular corrugations act like the
grooves in a phonograph record, and the wheels provide the stylus!
Enough howl and you generate sufficient vibration to interfere with
system equipment.

	I don't know what sort of lubrication or construction they
needed to prevent this, since it's tough to maintain a single stretch
of underwater track that's designed for 80MPH at full loads.  

	There's a great saga of the BART/Westinghouse/HP/LBL feuds in
the early 1970s up at http://www.pushback.com/Wattenburg/bio/BART.html
if you have the time.  Wattenburg was a crazy inventor, and even
showed how the ticketing machines could be fooled with a tampered
ticket into providing unlimited rides (he followed good security Full
Disclosure practices, but the flaw remained so long that he eventually
went to the Chronicle with the technique!).

"Forget the damned motor car and build cities for lovers and friends."
	-- Lewis Mumford


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