The following is part of an artice in the September 1933 issue of Railway Signaling Magazine.

“Consolidated Interlockings and Block Offices”

A 12-Mile Centralized Control System

On the Wilkes-Barre Division, a remote-control system was installed on a 12-mile territory between Douglassville, Pa., and Seyfert, Pa. This single-track line extends from Spring City to New Boston Junction on the line between Philadelphia and Wilkes-Barre, and handles 16 passenger trains and about 8 freight trains daily. At Douglassville there was previously an eight-lever mechanical interlocking which handled the west end of the passing track and also served as a block office. Likewise, at Seyfert, Pa.,an eight-lever mechanical plant handled the west end of the passing track and this plant was also a block office. The other end of each of these passing sidings was hand operated. At Brooke, the east end of the passing siding was connected to an interlocking which included a crossing with the Reading; however, the west end of this siding was hand-operated. In order to improve train operation by reducing delays, as well as to reduce operating expenses, it was decided to eliminate interlockings at Douglassville and Seyfert, and install power-operated switches for both ends of the passing sidings at these points as well as for the west end of the siding at Brooke, the installation to include signals for directing train movements and the control machine in the existing tower at Brooke to afford OS indications at the various points, so that, in effect, this is a centralized traffic control system, although the equipment, circuits and control machine are similar to those ordinarily used for remote-control layouts. The standard circuits for the remote control of an outlying switch, as used on this installation, are shown in the accompanying diagram.

The Union Style-M switch machines are equipped for operation on 24-volt direct current. The signals are the three-indication position-light type. The signal at the entering end of a siding has a lower arm for directing movements into the siding. The dwarf signal for movements out of the siding displays two-indications. Each head-block signal – i.e., each signal for directing train movements at the facing-point end of a passing track – is protected by a distant signal.

As part of the improvement program, Type-T10 hand operated switch-and-lock movements with pipe connected derails, were installed on all main-line switches leading to industry tracks. Furthermore, where these switches did not come within the distant-signal limits, additional switch-protecting signals were installed at several places where these switches could not be seen readily from an approaching train. All signals are track circuit controlled, and approach track circuits are used as annunciator sections, where required. Therefore on the 12-miles of single-track main-line involved in the installation, a total of 12 miles is equipped with track circuits. It should be noted however, that this is not a continuous automatic-block-signal installation, but rather a series of remotely controlled layouts, train movements between stations being controlled by traffic locking.

The control machine in the tower at Brooke consists of a set of 20 table-interlocker units with mechanical locking. The mechanical in the tower has 70 levers, and in order to eliminate confusion between lever numbers, the table interlockers were numbered from 71 to 91. Twelve of the units are for 33 signals and traffic control, 6 levers for 7 switches, and 2 levers for 8 electric locks. The machine is mounted on a channel-iron bed supported on three 3-in. pipe posts over the operators desk.

The switch levers operate to two positions: normal at the left and reverse at the right. The signal levers are normally at center and operate to the left for eastward signals and to the right for westward signals. In the indication panels above the the signal levers, one light is illuminated when the eastward signal is indicating Proceed and the other light likewise repeats the westward signal. The light in the right-hand indication panel above a switch lever is extinguished when a train is occupying the detector track circuit which includes the switch. Thus, this light is in effect an OS report of the passing of a train. The switch lever, is of course, locked up by mechanical locking and in addition it has an electric lock, controlled by approach and detector locking circuits. A push-button in the left panel above the switch lever is connected in the electric lock circuit and must be pushed to pick up the lock, thus serving as a battery-saving device.

Operation of the Control

When a westbound train due out of Hill, 6 miles east of Douglassville, the operator at Hill calls the operator at Brook for an unlock, which is effectrd by reversing lock lever No. 71. If the line is clear, the operator at Brooke can then set the other levers for the train movement through his territory, or if a meet is to be made with another train, he sets the levers as required. When an eastbound train is to be moved from Douglassville to Hill, the operator at Brooke must get an unlock release from Hill, before he can clear the eastbound block signal at Douglassville. A similar arrangement is in effect between Seyfert and Reading, the next block-office westward. The traffic-direction locking between Douglassville and Brooke, as well as that between other stations in this territory, is effected by the mechanical locking in the desk-lever set.

A special arrangmement is provided to co-ordinate the operation of the mechanical interlocking at Brooke with the table interlcoker control system. Table interlocker lever No. 78 is the master check lever and is locked normal by circuits through controllers on certain levers on the mechanical machine, so that the route through for the Pennsylvania must be lined up before check lever 78 can be reversed. Likewise certain of the table interlocker levers must be normal in order to place the check lever normal and thus release the electric locks on the levers of the mechanical machine.

As mentioned before, the outlying hand-throw switches are equipped with T-10 mechanisms including electric locks. These electric locks on the territory from Brooke east are controlled by lever No. 77, and those west of Brooke are controlled by lever No. 82. These levers are normally on center, and are thrown to the left or right, depending upon the direction from which the train is coming.

Detail Equipment

At Brooke, the relays, battery, etc., for the remote-control installation are housed in two large wooden cases located outside the tower. These cases have false backs with space for incoming wires, each going through a hole to the terminal on the face of the board. The line control circuits are on No.9 bare copper wire run on the signal pole line. At each power-switch layout there is a battery of 20 storage cells for switch operation and signal standby. One cell of the same type is used on each track circuit. All storage battery is on a-c. floating charge through Union rectifiers.

Cost Figures

This installation, which cost about $72,000, has been a great assistance in reducing train delays in this territory, due principally to the elimination of stops at the passing-track switches not previously included in the interlockings. The interlockings and block offices at Douglassville and Seyfert were abandoned, thus effecting an annual savings of $19,200. Therefore, considering this item alone, the signalingwill pay for itself in about 3 ¾ years. The installation was planned and installed by signal-department forces of the Pennsylvania.