Potomac Yard clearance limitation, or was it the Baltimore tunnels?

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Subject: Re: Potomac Yard clearance limitation, or was
it the Baltimore tunnels? 
Date: Fri, 1 Jul 2005 13:22:28 -0400 

Frank

Certain vertical clearance "high and wide" traffic
moving through the Pot Yd Gateway was always
conditional and was governed by each of the tenant 
lines most restrictive controlling structure in the
cars route north and south of PY.

On the Southern the most restrictive controlling
structure on the Wash Division was an overhead bridge
just north of Charlottesville which limited vertical
height to about 18 feet or so as my old Sou Ry
Clearance chart shows. This structure is still there
but the NS undercut the track to permit a clear
vertical height operation at 19'1"  (always with a 6"
clear margin) when they started operating thru trains
via the Weed Line. Sometime in 1977 Sou also undercut
the tracks under the RF&P OHB at CR Tower to handle 
Plate F 17'0" box cars.

North of DC the PRR PC and CR (now CSXT) have always
been governed by the most restrictive structure which
is Va Ave Tunnel in DC. In 1977 all of the major
RR's on the east coast agreed to improve all
clearances on all main and secondary mains to permit
the operation of Plate F cars (17'0") between
Canada and Miami and to the southwest via Atlanta etc.

In the 1977 clearance improvements project the Va Ave
tunnel was undercut enough to just get a 17'0" x 10'8"
wide at the top height box through and trailers or
containers at 17'6" x 9'0" in the crown. That was the
absolute max that they could get and is still the
controlling structure on the east coast via CSX.
Howard St Balto can handle 19'1" but the poor old B&P
is still Plate B unrestricted (14'6").  B&P can handle
Plate C 15'6" and trailers at 16'2" but trains must
run 2 and the G at John St and Pennsylvania Ave dating
from the 1917 PRR initial clearance improvement
project.

In 1977-78 all of the trolley wire and cat system
support wire from electrical ops were removed in Va
Ave  and at other locations just enough to get an 18
ft clearance. All Pot Yd wire was always High Wire
Territory with the wire at 22'0" ATR. So there was
never a problem in PY except at RO where the wire came
down to 19 ft to cross the bridge.

As a note some of the old 1904 trolley wire supports
on the Pot River Br that was still there was used by
the PRR to hang the 1936 wire installation.  Check out
the old supports and hangers under Commonwealth Ave
Br.  The Ford, Chrysler and GM traffic to PC and CR
points was restricted to 19'1" acct that's the max
that AMTK could get at Newark Del, Linden and Metuchen
for fully enclosed racks. 20' 2" can still only be
handled at Oak Island and on the Lehigh Line - RDG via
Trenton-Woodbourne-Hbg until the NS undercut the
Plattenburg tunnel on the Lehigh Line in 2001 east of
Allentown permitting 20'2" cars to go direct Oak
Island - Conway.

Jim


July 1, 2005

Thanks for the informative reply, Jim.

Have an excellent 4th,

Frank



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