SHJ Interlocking Tower

[Jim Holland]

Greetings!

Dietrich, Robert J. wrote:

> 1. The derail was changed to a single point standard street type point but
> with NO mate.  The left rail was T rail with concrete up to the flangeway.

	That stirs some memories - I remember the concrete being marked up as
well!

2-&-3.  2-aspect light becomes three.

> 4. I disagree about the type of switch unless you mean single point railroad
> switch.

	When operated by the switch tower, I believe that the outbound switch
was a pure railroad switch - 2 moveable points operated by a lever from
the tower - this would make sense.  If you were to look at the cover of
the 1994 PTM calendar, I think you would agree that - although
definitely at a distance - the turnout appears to be a double point RR
switch.  The tower still exists and is apparently in operation.
	When converted to US&S signalling and interlocking, the trackwork was
rebuilt as well.  The double point RR switch would be converted to a
single point and mate - very long ones - for operation from an overhead
contactor.
	Do you mean a single point RR switch and mate after conversion to US&S
signalling?  If I remember correctly, this was a standard street-type
point in the 1950s.  I seriously doubt that they would make it a single
point RR switch and mate.  The street type comes with a built in toggle
for holding the turnout when it is thrown to either direction.  The
toggle action is not in the switch machine motor as it is in the
models.  With a single point RR switch, a special toggle would need to
be built.  Additionally, a single point RR switch would have much more
movement than a single point street type switch.  The point is needed to
guide the opposite wheel through the mate so a RR type point would not
be good for this; a single point RR switch is not designed this way.  It
could probably be done, but it would take some very special designing.

> The far left rail is girder rail all the way to the switch point.
> Compare this to the picture in
> http://www.voicenet.com/~dietrich/SHJ/interloc.htm taken in 1939.

	Yes - this is for the conversion to overhead contactor operation of the
turnout - the 2-point RR switch is converted to point and mate.

> Originally this was T rail with, I guess, double point switches and guard
> rails in the appropriate places
> http://www.voicenet.com/~dietrich/SHJ/oldover.htm

	And this is what I was saying - the original installation and the
operation by lever from a tower had a double-point-RR turnout outbound
at the South end of the tunnel.

> A couple more details:  The railing bounding the pedestrian area stayed, it
> was there since the mid-teens, as did the concrete walkways to the front  of
> the tower.  The area between the inbound rails from that railing to the
> derail was paved in 1947 http://www.voicenet.com/~dietrich/SHJ/bv5.htm but
> ties showed in 1968  http://www.quuxuum.org/~joekor/pittsburgh/1550020.gif.
> PRCo kept the public informed with that dirty sign hanging on the railing
> showing downtown routing.

> My favorite detail on this picture is the bar across the tunnel entrance
> that keeps tension on the overhead when modules are broken down for
> transport.

	Is that what PRCo used it for as well?!?!<VBG>  What was it for in the
prototype.

>  -----Original Message-----
> From:   Jim Holland [mailto:pghpcc at pacbell.net]
> Sent:   Saturday, April 22, 2000 6:21 AM
> To:     PRCo -- WP -- JTC -- The Big *3* --
> Subject:        SHJ  Interlocking  Tower

> Greetings!

>         The 1994 PTM calendar cover shows a DE-low-floor car on 48-Arlington
> entering the tunnel and a SE-low-floor on the 44-Knoxville exiting the
> tunnel with a clear view of the double-story interlocking tower in the
> triangle between the two-track wye!  The photo is taken just beside the
> Char-Wash-38-39-40-42 track lead into the tunnel.

>         Some interesting details are noted here:::::::

>         1)--The derail is a single-point RR switch without mate!
>         2)--2-aspect signal light beside the derail.
>         3)--On the line pole immediately in front of the tower is what
>                 looks like a small yellow light with DERAIL
>                 written vertically below it.
>         4)--The outbound turnout out of the tunnel appears to be
>                 a railroad switch - ala the turnouts for the sidings
>                 on the interurbans.
>         5)--Piping from the tower lever throw for above mentioned
>                 turnout is clearly visible!
>         6)--The tower controls five turnouts:
>                 a)--Outbound out of tunnel
>                 b)--Derail for 44-48
>                 c)--Derail for Interurbans-38-39-40-42
>                 d)--Turnout from Interurbans-38-39-40-42 to 44-48.
>                 e)--Turnout from 44-48 to track behind Admin bldg.

>         The photo must be pre-1939 when this junction was converted to
> automatic interlocking.  ALL the above would be changed:::::::

>         1)--Derail changed from one RR point to standard street-type
>                 point and mate.
>         2)--2-aspect signal light beside derail becomes 3-aspect.
>         3)--The DERAIL sign with yellow light is removed.
>         4)--The outbound turnout out of the tunnel is changed from
>                 an RR switch to standard point and mate type.
>         5)--Piping to throw the switch from the tower is removed.
>         6)--ALL the switches controlled by the tower converted to
>                 electric switch operated by trolley contactor.

>         And of course, the tower itself was removed!

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