Speed--Tunnel

[Jim Holland]

Greetings!

Fred Schneider wrote:
> 
> Seems to me that it took in the neighborhood of 30 minutes from South
> Hills Junction through the city and back out.

	Generally true!  While the trolleycars had mucho traffic downtown to
contend with in addition to traffic signals  --  depending on the time
frame  --  there was also a tremendous amount of traffic in trolleycars
themselves which would slow operations.
	The 1950 Char and Wash interurban schedules list betwen 25-minutes
roundtrip SHJ-Pgh-SHJ to 27-min in the PM peak.  The 1957 interurban
schedule is not that specific about running times, but the 1964.04.26
schedule lists 22-minutes roundtrip.
	The 38-39-42 used a slightly different route but their 1961.07.23
schedule lists 22-min. round trip SHJ-Pgh-SHJ weekdays, 19-minutes for
the same on Saturday, and 18-minutes on Sunday schedules.
	The 42/38 schedule effective 1964.04.26 for SHJ-Pgh-SHJ lists
20-minutes for the AM rush, 22-minutes for the PM rush, and 19-minutes
off-peak weekdays; 19-minutes Saturday; 17-minutes Sunday.

> While the traffic lights
> and general congestion did consume a lot of time, I'm inclined to agree
> with John that at least 6 to 8 minutes of the total was between the
> north bank of the river and the south end of the tunnel.

	That would be roundtrip or 3-4 minutes each direction.

> My earlier
> guess of 100 seconds was based on car balancing speed up hill ...  my
> memory of balancing speed ... I was thinking in terms of 25 mph but it
> might be closer to 20 mph on a 6 percent up hill gradient ... that works
> out to 29 feet per second.

	A paper by H.G. McClean, B.Sc., M.I.E.E., M.I. Loco.E, Manager,
Crompton West Traction Bureau called  ""The American P.C.C. Car""  was
published in the 1945.12.14 issue of the British  *Passenger Transport
Journal* and includes the following quoted information on PCC
speed:::::::

	""The maximum speed is 42 m.p.h. on level tangent track, with a maximum
safe speed downhill of 50 m.p.h.; . . .""  (pg. 348).  The included
chart reveals that in 60 seconds the car could reach about 38 m.p.h. on
level tangent track after travelling about 2700-2800 feet.

	""Smooth multi-notch acceleration is obtained, fully automatic by pedal
control, the driver selecting the rate of acceleration between limits of
1.5 and 4.75 m.p.h.p.s.""
	""The normal service brake is the electric rheostatic brake and this
provides a contribution of 3.5 m.p.h.p.s. of the maximum brake rate of
4.75 m.p.h.p.s.""  I believe the track brake provided the balance of the
*service brake rate* as the track brake had two settings - minimum and
full application of the track brake, the latter used in emergency
braking (pg.-348-349).

	""The maximum speed is 42 m.p.h.; balancing speed is 28.5 m.p.h up a 6
per cent. gradient.""  (pg-349, second column, under heading *Start.*

	According to a mid-60s map of the interurbans, 42/38, and 39 lines
which I obtained from PAT, the official length of the tunnel is 3,498
feet.  At 28.5 m.p.h. up a 6% grade, that is 44 feet/second, or 79.5
seconds for the outbound trip through the Mt. Wash trolleycar tunnel. 
But the car doesn't enter nor leave the tunnel at that speed, so 90-100
seconds would seem reasonable.

> Inbound was probably slower unless you had
> an idiot for a motorman, and there were a few of them around.  The other
> issue is that rail cars always tend to be noisy, particularly in
> confined spaces, and tend to make one think they are going a lot faster
> than they really are.

	This is what I, too, had deduced originally.  Outbound in the Mt.
Washington trolleycar tunnel, it is very easy to put the
*pedal-to-the-metal* and maintain a very constant and relatively fast
speed uphill.  That is more difficult to do inbound and I believe that
the inbound ride was slower  --  most of the time!

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