Symbol index

These are the most common symbols (and a few not-so-common ones :-) that are used in these track diagrams. I wrote an explanation of how to interpret the signal symbols as well.

Automatic block signal.
Automatic block signal.
Interlocking signal.
Semi-automatic interlocking signal.
Interlocking dwarf signal.
Phase break signal (position-light style).
Signal bridge. This structure is not a part of the catenary system. These are either the PRR-style signal bridges or newer I-beam construction.
Signal bridge that is part of the catenary support structure. Typically, a cross beam mounted on catenary poles.
Slide signal indicator. Like the image shows, it is a plate mounted on the signal mast with the letters "SP". If the signal displays a "stop and proceed" indication, the engineer must assume that it might be due to the slide fence being broken (along with any other reasons why the stop-and-go could be displayed -- another train in the block, etc.).
Dragging equipment and hot journal detectors. These show bi-directional indicators; if a detector operates for movements in one direction only, one side is shown to the right (engineer's) side of the track it governs. Dragging equipment and hot journal indicators can be located together, or independently of one another.
Electrically locked hand-operated switch. A controlled electric lock will also show a lever number that corresponds to the operator's machine lever.
Hand-operated switch, not electrically locked. Generally not found on main tracks, for good reason!
Milepost. Typically, these are not 5280 feet apart from one another! They are usually close, though. One blatant exception: Milepost 69 and Milepost 70 at Cork are about 1200 feet apart -- I thought I did the "fastest mile" when I walked the west end of the interlocking! The present Lancaster station was built in the late-1920s, with the right-of-way on a new alignment that skirted the central business district of the city. MP 68 is measured from Broad Street Station Philadelphia, MP 69 is on the new alignment and is also effectively measured from Phily, but MP 70 is measured from Broad Street Station via the original alignment. There were numerous other ROW realignments made over the years (many as part of the electrification project) that have caused similar "short" miles -- but none as extreme as this example.
Highway grade crossing with flashers and gates; I can't think of any grade crossings on the division that aren't so equipped.
Station platform; inter-track fence.
Interlocking tower. The dot and line are supposed to represent the location of the operator and the interlocking machine -- or machines (look at Overbrook, which has its original US&S Model 14 machine and a newer CTC-style machine). I will admit that I wasn't 100% accurate on these; State should have two additional lines for the Roy and Harris machines.

Maps Home

Ken Reinert <kreinert@erols.com>
Most recently updated: November 27, 1997.

	Automatic block signal.
	Automatic block signal.
	Interlocking signal.
	Semi-automatic interlocking signal.
	Interlocking dwarf signal.
	Phase break signal (position-light style).
	Signal bridge. This structure is not a part of the catenary system. These are either the PRR-style signal bridges or newer I-beam construction.
	Signal bridge that is part of the catenary support structure. Typically, a cross beam mounted on catenary poles.
	Slide signal indicator. Like the image shows, it is a plate mounted on the signal mast with the letters "SP". If the signal displays a "stop and proceed" indication, the engineer must assume that it might be due to the slide fence being broken (along with any other reasons why the stop-and-go could be displayed -- another train in the block, etc.).
	Dragging equipment and hot journal detectors. These show bi-directional indicators; if a detector operates for movements in one direction only, one side is shown to the right (engineer's) side of the track it governs. Dragging equipment and hot journal indicators can be located together, or independently of one another.
	Electrically locked hand-operated switch. A controlled electric lock will also show a lever number that corresponds to the operator's machine lever.
	Hand-operated switch, not electrically locked. Generally not found on main tracks, for good reason!
	Milepost. Typically, these are not 5280 feet apart from one another! They are usually close, though. One blatant exception: Milepost 69 and Milepost 70 at Cork are about 1200 feet apart -- I thought I did the "fastest mile" when I walked the west end of the interlocking! The present Lancaster station was built in the late-1920s, with the right-of-way on a new alignment that skirted the central business district of the city. MP 68 is measured from Broad Street Station Philadelphia, MP 69 is on the new alignment and is also effectively measured from Phily, but MP 70 is measured from Broad Street Station via the original alignment. There were numerous other ROW realignments made over the years (many as part of the electrification project) that have caused similar "short" miles -- but none as extreme as this example.
	Highway grade crossing with flashers and gates; I can't think of any grade crossings on the division that aren't so equipped.
	Station platform; inter-track fence.
	Interlocking tower. The dot and line are supposed to represent the location of the operator and the interlocking machine -- or machines (look at Overbrook, which has its original US&S Model 14 machine and a newer CTC-style machine). I will admit that I wasn't 100% accurate on these; State should have two additional lines for the Roy and Harris machines.