This is used for trains negotiating complex trackwork at interlockings.

Slow Speed - 15 miles per hour while with in the limits of a interlocking and 20mph when not in the limits of a interlocking. This is the typical speed for diverging movements through interlockings and is also the speed trains are limited to when approaching a Stop or Restricted Proceed-type signals.

Medium Speed - Original concept for a standard 'reduced' speed normally set to 30 miles per hour. This speed is defined by individual railroads and ranges anywhere from 40 miles per hour, to 60 miles per hour. Limited Speed - A speed less than Normal Speed that was employed starting in the 1940's for use with higher speed switches. Normal Speed (MAS) - The normal speed for the railroad line, also known as Maximum Authorized Speed. The following speeds are also used in Route type signaling: The aspect indicates the conditions of the block or block ahead, as well as the speed to do while passing that signal and the speed to be at when approaching the next signal ahead. LIRR/PRR used a system of speed signaling which means the signal indicates at least 2 pieces of information to the operator. Signal rules and aspects make use of several pre-defined speeds. Non-interlocked signal which displays 'STOP SIGNAL' (Rule 292) as its most restrictive aspect In simplest terms, a 'home signal' is an interlocking signal or The 'Dwarf Pedestal' is referred to simply as 'Pedestal(s)' Note: On the LIRR the 'Dwarf' signals are referred to as 'Low-Homes', These are only found in interlockings. We will take each individual Position Aspect and describe what it means. This is an over view of the LIRR/PRR system. The lamp units and background disc on a mounting system known as a 'spider,' were integrated into a single unit.īelow, you will see a chart of position light signals, with an accompanying rule number. There were found issues with wind damage due to the rather larger 'sail area' of the 'tombstone backing.' Soon thereafter, the lamps were reduced in number to three per row, without adversely affecting the long range viewing of the signal aspects and the backing correspondingly reduced in size and made as a disc. These first signals differed from the later ones in that the lamps were mounted separately in front of a tombstone-shaped black painted metal backing. The first installation of the four 5 volt 10 watt lamp position light signals occurred on the Mainline between Philadelphia and Paoli, in conjunction with the 1915 electrification. The prototype position lights used rows of four lamps in an asymmetric fashion in the style of semaphore blades, but this was later changed to the symmetric three-lamp system. The Pennsylvania Railroad chose to use their Superintendent of Signaling, A.H.Rudd's, in-house developed position light signals to both replace the semaphores and their moving parts, also because the intense lemon yellow light provided superior visibility in adverse weather conditions such as rain, fog or snow. Multiple signal heads were used at interlockings where four aspects did not suffice. Lamps with inverted half toric optic lenses, covered with a light yellow tinted conical cover glass with a frosted tip to avoid phantom indications were displayed in rows of three, corresponding to the positions of a semaphore blade. (The PRR realized that 1 in 3 engineers were color blind). This had the advantage of eliminating any and all effects of even slight color blindness by the train crew. On the Long Island Rail Road as on other railroads, initial efforts were made to replace the semaphore signal's with the illumination of the position of the blade rather than by color lamps alone. In many countries, small position light signals are used as shunting signals, while the main signals are of color light form. The aspect consists solely of a pattern of illuminated lights, which are all of the same color (typically amber or white). A position light signal is one where the position of the lights, rather than their color, determines the meaning of the aspect that's being conveyed to the Engineer or other designated employee leading the move.

Prr semaphor train signal rules