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The New Zealand Railways Magazine, Volume 1, Issue 7 (December 15, 1926)

Progress on the Pennsylvania Railroad — Modern Signalling Developments

page 38

Progress on the Pennsylvania Railroad
Modern Signalling Developments

Extension of automatic signals and train control devices now being made on the Pennsylvania Railroad involve expenditures totalling £8,000,000. The expenditures being made at this time represent the greatest investment and most extensive installation in signal proteetion ever undertaken on the Pennyslvania Railroad or any other railroad at one time.

Important new principles to guard against failures in the observance of signals are being worked out by the company in connection with this programme. A new device has been designed which consists of electrically operated meehanism by which the indication given by the “wayside” signals—that is the signals displayed on masts at the side of the track or on overhead signal bridges—is duplicated in miniature within the engine cab, keeping the indications continuously before the engineman and fireman.

In addition to the engineman and fireman having continuously before them signals in the cab, each “less favourable” indication by these signals is immediately called to their attention by an audible warning—a whistle which is conneeted with the signals. There are two sets of signals in the cabs, one on the engineer's side and the other on the fireman's side. Thus, each will receive an identical separate warning.

A train control system involving these cab signals, and what is known as a “stop and forestaller” device, has just been completed on the Pennsylvania Railroad's main line tracks between Harrisburg and Baltimore. This involved the equipping of approximately 150 locomotives with the necessary electrical and mechanical apparatus for the operation of this system, which is actuated by electrical circuits in the track itself.

The present programme of the Pennsylvania Railroad for the extension of cab signals and train control covers the main line from Harrisburg to Altoona, the main line from Camden to Atlantic City, the main line of the Panhandle Division from Pittsburg to Columbus, Ohio, and the main line of the Columbus Division from Columbus to Indianapolis.

When the current programme is completed approximately 1,150 engines will be equipped with the cab signals and other control devices, while the necessary electrical apparatus will be applied to 1,530 miles of track.

The “stop and forestaller” is a device so arranged that as a train passes a signal showing any indication except “clear,” the air brakes will be automatically applied unless the engineer “acknowledges” the signal as repeated in the cab by working the “forestaller” controlled by a small lever in the cab. This action “forestalls” the automatic operation of the air brakes, but of course will not be taken unless the engineer has observed the signal and is therefore informed as to the track conditions ahead, permitting him to bring his train under control.

The electrical system adopted in the installation between Harrisburg and Baltimore is limited to three signal indications in the cab. These are “clear,” “approach” and “slow.” The new plan which has been worked out, and which is known teehnically as the “coder system,” permits four indications, namely, “clear,” “approach,” “approach-restricting” and “stop.” The “approach-restricting” signal is used to show conditions three blocks ahead for which way-side signals are provided on various portions of the railroad. Four signals permit a more complete and satisfactory repetition in the cab of the “way-side” signals than is possible with only three indications.

Engineering and transportation authorities credit the Pennsylvania Railroad with having been a leader in the perfeeting and adoption of devices for increasing safety in train operation for more than half a century.

A trial installation of an automatic train stop was made on The Pennsylvania Railroad as early as 1880. The Pennsylvania was the first to give Westinghouse a hearing and try out his air brake, which made quick stops possible, and thereby rendered high speed safe. Since then, inventive genius has been incessantly at work perfecting the signal system.

The Pennsylvania was the first railroad in America to install an inter-locking plant for the safe handling of switches and their co-ordination with signals from a central point. It was also the first to use the manual block system of signals. This was in 1863. Nine years later the Pennsylvania was the first to use the closed track circuit, by an installation at Irvineton, Pa.

In 1906, at West Philadelphia, the company employed the first upper quadrant three position signals of the electro-pneumatic type. A year later, between Huntly and Cameron, it was the pioneer in operating the control manual block signal system with continuous track circuit. In 1911 it developed the first three-block signals in the vicinity of Jersey City. A three-block indication page 39 tells the engineer the condition of the track for three blocks ahead instead of two, a distance of some miles.

The Pennsylvania Railroad was the first to develop the “position light” signals, in which fixed rows of powerful electric lights took the place of moveable semaphores giving daylight indications, and coloured lights giving night indications. The “position light signals” are now used in all new installations and are gradually supplanting the old system.

All of these engineering developments and many others have been completed and successfully developed to make possible the train control device now being installed.

N.Z. Railway Commissioners Office Staff, 1891 Back Row: J. E. Widdop, A. G. Millward, J. G. Pepper, F. S. Pope. Front Row: J. F. Bell, T. W. Waite, C. F. F. A. R. Isherwood

N.Z. Railway Commissioners Office Staff, 1891
Back Row: J. E. Widdop, A. G. Millward, J. G. Pepper, F. S. Pope. Front Row: J. F. Bell, T. W. Waite, C. F. F. A. R. Isherwood

At the present time the Pennsylvania Railroad has 14,355 miles of main track, and all its passenger train service is operated under and protected by the block signal system, much of which is of the automatic type. Automatic block signals cost more per mile of line protected than any other, and the Pennsylvania Railroad's investment in them is many millions of dollars.