PRR Interlocking Diagrams: Altoona to Pittsburgh Main Line

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Help me guess the meanings of tower Morse Code designations!

Key for present guesses: [X = ?] clue; [X ??= Y]...possible; [X ?= Y]...probable; [X = Y]...likely to certain.

Main Line -- Harrisburg to Pittsburgh

[Starts in Altoona with ALTO and SLOPE interlockings: see the Harrisburg to Altoona page.]

The interlocking diagram index indicates a Sheet 1, "Altoona, West of 'GY'", which is missing from the copy I borrowed for scanning. If anyone has this in their collection, please email me. Numbers in brackets below are sheet numbers.

[2] MG, above Altoona, Pa.

42K, 200 dpi
[MG = middle of grade] A very remote interlocking and tower. In recent days (?and in PRR days) it was open only when there was track maintenance. The access road is long and arduous, and likely impassable in winter.

[3] BF, SF, AR, UN, Tunnelhill and Gallitzin, Pa.

131K, 200 dpi
[BF ?= Benny (Bennington) Furnace; SF = ?; AR = AllegRippus; UN = ?] [thanks to Derrick Brashear] At the crest of the Allegheny Front, southwest (RR-west) of Altoona. SF is where the New Portage Branch joined. This branch was a bypass of the main line, passing around the Mule Shoe Curve to Hollidaysburg and WYE interlocking.

[4] MO, Cresson, Pa.

50K, 200 dpi
[MO = MOuntain] [Sean McDonnell] Junction of the Cresson Secondary, which soon splits into several area coal branches.

(For sheets 4A, 4B, see Branches and Yards page.)

[5] BC, NY, Portage, Pa.

72K, 200 dpi
[BC = Ben's Creek; NY = ?]

W, SO, South Fork, Pa. (101K, 200 dpi) [6]

[W = Wilmore; SO = South Fork (of Conemaugh River)] Location where the South Fork Secondary branched to the south. This branch served mainly local coal fields.

This map was quite badly faded at both ends, especially so at the eastern (right) end. Anyone with a good original, please email me. Questions: 1) is the lower marker of 2613-3 filled in? 2) what about signal 2678-3? (I suspect both are "typos".) 3) The signals for eastward traffic on the same signal bridge as the 2637 signal, are they 2636 or 2638? 4) Signal 2612-3 has no lower vertical arm on this drawing, where it clearly has one on the drawing of BC-NY above. Much of the 2612-2613 bridge was reconstructed from the BC-NY map, though the originals clearly differ.

AO, east of Conemaugh, Pa. (43K, 200 dpi) [7]

[AO = After Oxbow; Keystone v22 #2 p21; thanks to Jean Gagne]

C, JW, Conemaugh (Johnstown), Pa. (97K, 200 dpi) [8]

[C = Conemaugh (River)] This tower is on the far eastern side of Johnstown, easily seen from the nearby road bridge over the Conemaugh River. C controls access to the Conemaugh Yard area.

SG, SQ, Sang Hollow (Johnstown), Pa. (83K, 200 dpi) [9]

[SG ?= Sang Hollow; SQ = ?]

JD, New Florence, Pa. (56K, 200 dpi) [10]

[JD = ?]

Junction, westward, of the Conemaugh main line.

JD--DR, [New Florence--Derry], 1957, G.O. 312
Map of changes accompanying removal of #1 track from JD to DR. This also shows the many intermediate signals, on this remote stretch of line, not shown in the interlocking diagrams. (The line is remote because it is coursing through the Johnstown Narrows, bypassing the Laurel Ridge, Laurel Highlands, and Chestnut Ridge, before exiting onto the plateau in the Derry-Latrobe area.)
(Index at front of book contains a scratched-out reference to BH at Torrance as being (having been) sheet 11.)

DR, MILLWOOD, Derry, Pa. (72K, 200 dpi) [12]

[DR = Derry]

KR, Latrobe, Pa. (67K, 200 dpi) [13]

KR = Kenner (after a Latrobe neighboorhood; a park still bears the name) [Derrick Brashear]
Latrobe is the town famous (?) for Rolling Rock beer and Arnold Palmer. The Unity Secondary and Ligonier Valley RR join into the mainline. Note that the western sub-interlocking has a switch and signal numbering scheme that is different from that of the eastern sub-interlocking. The western section was apparently controlled by the mechanical machine (?). Note the separate numbers for upper and lower arms of interlocking signals.

SW, Greensburg, Pa. (129K, 200 dpi) [14]

[SW = Southwest Secondary] Divergence point of the Southwest Secondary Branch which ran to Youngwood and Connellsville, Pa., partially paralleling the westernmost end of the Western Maryland in the process. This region was rich in coking coal. The Monongahela Division main line from Pittsburgh ran through Brownsville Jct. and joined the Southwest Branch at Redstone Jct. The new tunnel was 'daylighted', i.e., the hill above it was blasted away, in the 1960s as I recall, to allow more clearance for cars.

The alignment for the old tunnel is visible from the west as a train next to a carpet store; from the east one can see the old abutments for a bridge over a road, just east of the hill. [updated by Derrick Brashear] The duckunder is also not easily visible, or gone, at present.

RG, Radebaugh (Greensburg), Pa. (82K, 200 dpi) [15]

[RG ?= Radebaugh, or Radebaugh Grade]

CP, Larimer, Pa. (61K, 200 dpi) [16]

[CP = ?]

(For Pitcairn Yard, see Branches and Yards page.)

SZ, UJ, Trafford, Pa. (83K, 200 dpi) [17]

[SZ = ?Stewartsville [sugg. by D. Brashear]; UJ ??= Union [RR] Jct.] Western end of Pitcairn Yard.

WG, PERRY, Wilmerding, Pa. (87K, 200 dpi) [18]

[WG = Wilmerding]

R, U, East Pittsburgh, Pa. (53K, 200 dpi) [19]

[R = ?]

WK, Swissvale, Pa. (38K, 200 dpi) [20]

[WK = entrance to Wilkinsburg Yard (thanks to LIBCTR@...)]

CM, East Liberty, Pa. (16K, ? dpi)
Large (147K) version.
1913 version.
Version sized to be similar to others on this page (82K) [21]

[CM = ?] In northeastern Pittsburgh. Main line to the east (right). Brilliant Branch, a freight bypass around the congestion of the downtown passenger station and local freight tracks, north (up). This branch crossed the Allegheny River, where a connection was made with the "West Penn" (now Conemaugh Line). The (main) passenger station is southwest (RR-west) of CM.

1913 version thanks to Geoff Lambert. First and large version from maps supplied with The Pennsylvania Railroad in the Steel City published by the Pennsylvania Railroad Technical & Historical Society, Pittsburgh Chapter. "Sized" version is reduced 66% from the large version to match approximately the size of the other maps.

DV, West of Shadyside (Pittsburgh), Pa. (42K, 200 dpi) [22]

[DV = ?]

BU, UF, US, PH, Pittsburgh, Pa. (27K, ?dpi) [23]
Large (236K) version.

[BU = ?; UF = ?; US ?= Union Station; PH ?= Pittsburgh or Panhandle] Pittsburgh Union (Pennsylvania) Station and surround. These 4 interlockings were later consolidated into one, PITT, sometime before 1961. PITT sported a 367-lever Union Switch & Signal Model 14 interlocking machine.

The reader may also be interested in this map (2095x2050, 48K) of the routes that freight trains took through Pittsburgh. The map is based on the 1960 freight schedules (on this site). Thanks to Henrik Hornb&ae;k Thomsen of Denmark for creating the map. Note that, since the freight schedules are not completely explicit about routing, some details on the map could not be confirmed. Confirmation is being sought from other sources.

Mark's Railroad-Related Stuff
A Pennsylvania Railroad Home Page
PRR Maps
PRR Interlocking Diagrams
Altoona to Pittsburgh: Main Line

Mark D. Bej
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