Pittsburgh Guardrails Was: [Re: Johnstown PCC Scans & a Pittsburgh Fantasy]

[Jim Holland]

Greetings!

Charles Brown wrote:
> showed some sections with 4 rails where
> there wouldn't be any need for guard rails nor were they the right
> spacing for such.

	Actually, this type of construction was very common on PRCo, 
especially bridges.  On page 81 of Harold Smith's *Touring Pittsburgh by 
Trolley* (that's a  t-h-i-r-d  b-o-o-k  I am checking  f-o-r  y-o-u; you 
darn well better be checking the reason for the Ultra-Wide-SCSI, I mean, 
track gauge in Baltimore!), the lower photo shows PCC 1234 inbound on the 
Palm Garden trestle with two inner rails.  They wouldn't be very useful 
as guard rails when the car derailed for they were spiked only every 3-6 
ties!.  Also the photo of 1654 coming down the ramp into W. Liberty Ave 
shows that girder guard rail with a high guard on it is used for the 
inner and outer running rail while a third rail is spaced about a foot 
from the inner curve rail.  The two extra guard rails were used on the 
trestles in Beechview as well.

	It is interesting to note that PRCo used a high guard on both the 
rails in a turn 90-95% of the time.  Most people think that all wheels 
press against the outside rail of the curve but this is not true.  Each 
truck acts like an automobile in that the rear axle does not want to 
follow in the same path as the front axle during a turn.  So the outside 
wheel of the back axle is pressing against the guard rail while the 
inside wheel of the back axle is pressing against the rail head; it is 
just the opposite for the lead axle - the outside wheel is pressing 
against the rail head while the inside wheel is pressing against the 
guard.  That is why the inside railhead and guardrail is shiny on both 
rails!  This caused excess friction in a turn but did not give any other 
problems.  While PRCo greased/oiled its switch points, they did not 
grease the guard rail in a turn!
	Additionally, it was common for PRCo to use a high guard on the 
tangent for *about* a truck length before and after each curve.  Once the 
front axle moves into the turn, the back axle wants to make a turn while 
it is still on the tangent so having the extra guard is good; having the 
extra guard coming out of a turn would allow the truck to stabilize on 
the tangent before the *guard is let down!*
	Think PRCo might be one of the few or maybe ONLY system that used 
a high guard on both rails of a turn.   SFO didn't and doesn't and there 
never seemed to be a problem.
	
-- 
James B. Holland
       PITTSBURGH RAILWAYS COMPANY (PRCo), June of 1949 -- June of 1953
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