South Hills Tunnel -- Street Track Centers & Spiral Easement Request

[Jim Holland]

Greetings!

	Absolutely fascinating information about the tunnel - glad you
specifically sent this to Bob to encourage him to build this in HO!!! 
Will be looking for photos of his efforts in *Trolley Talk* some day!

Fred Schneider wrote:

> The gauge line of the inner rails was 5'-0".  Because we are converting to
> standard gauge for models,

	We am?!?!  Not in "O" Scale!  With 1.25 inches between the rails in "O"
Scale we are almost perfect Pennsylvania-Pittsburgh Broad Gauge (one
must add about 0.06 inches, or *almost* 1/16th inch, to the 1.25 inches
to be perfect gauge in "O" Scale.)  So the actual distance between two
PRCo PCCs in the tunnel is about 22 inches!  It might be close to 26
inches betwen two of the older cars.

> this left a rather abundant devil strip of about 26" depending on
> car width

	On some streets in Pittsburgh, the distance between the inner side of
the two inner rails was 4 feet 4 inches leaving about 14 inches between
two PCCs or more than 0.25 inches but less than 5/16 inches between two
PRCo "O" Scale PCCs.  That's mighty close for modelling purposes.

	Do you have any information on spiral easements used by PRCo to head
into and out of turns on the inside track of a double track turn? 
Similar was used when switches were involved in the turns.  Of course,
there were some turns so tight that even this was not possible - many
turns were strictly NC - Non-Clearance - and two cars could not pass in
a turn!  In many instances, rulebooks forbade passing on turns, anyhow,
even if built for that possibility!

James B. Holland
------- -- ---------
        Pittsburgh Railways Company (PRCo), June of 1949 -- June of 1953
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