Interlocking switches are operated by Pedestal type signals display high-speed electro-pneumatic machines a complete range of aspects

Pennsylvania Railroad Installs

Large Modern Interlocking

At Passenger Station in

Panel-type control machine uses thumb-type turn-and- Arsenal interlocking with the four- track line toward and push "levers." Turn of signal lever completes route Washington. Northward from the check network, and lights "exit" lamp on track dia station, the tracks converge to two gram, and the lever is pushed to clear the signal double-track routes, connecting at Zoo interlocking to four-track lines, one east to New York, and the other IN PHILADELPHIA, a large inter westward, with a subway station west to Harrisburg. locking, employing new practices at station, Thirtieth and the most modern appliances, Street. This subway system will pro New All-Relay Interlocking has been installed at the Pennsyl vide transportation for passengers The plan herewith shows the vania Station, Thirtieth Street, which to and from various parts of the city. track layout and signals of the entire replaces interlocking facilities at the new interlocking at Pennsylvania old Broad Street Station. The sta Ten Tracks in New Station Station. The interlocking machine is tion at Thirtieth Street was built a In preparation for handling, not on the fourth floor of the station number of years ago, at which time only 77 north-and-south through building, at a location where the only two through tracks were in trains, but also the greater portion of leverman has no view of the tracks. stalled, and later modified to include the trains, other than MU trains, The panel of the control machine is four station tracks, to handle ap originating and terminating at Phila 5 ft. 4 in. high and 10 ft. long. The proximately 77 through passenger delphia, the track layout at Pennsyl track diagram includes blue traffic- trains operating on the north-and- vania Station was expanded to pro direction lights, amber lamps which south route between New York and vide a total of 10 through tracks, are lighted to repeat track occu Washington. During this time, ap served by five car-floor-level plat pancy, white exit lights, and red proximately 135 passenger trains forms. The tracks are at ground level, lights to indicate trolley sectionaliz- daily, which originate and terminate and the station is overhead, with ing. On the track diagram, each at Philadelphia, have been handled moving stairways extending up from signal is represented by a green in the old Broad Street Station in the the platforms. These platforms arc lamp which is lighted when the cor main business district, about 0.9 mile 1,330 ft. long. responding signal has been cleared east of Thirtieth Street. During this From the south end of the station, to display any proceed aspect. period, the city of Philadelphia has the tracks converge to a double- The levers on this panel are the been extending the subway system track mainline south, connecting at so-called thumb-button type. The

MAY, 1952 RAILWAY SIGNALING and COMMUNICATIONS 31 1 switch levers are painted black, the ward signal. A red indication lamp signal which is indicated by a green signal levers red, and the check is located over each signal lever to light on the track diagram. levers are blue. The switch levers are indicate that the signal is in the stop The white exit light is extin in a row under the track diagram. position. guished when the train accepts and A group of three-indication lights is passes the signal leading to the route. located above each switch lever. An Exit Lamp Shows Route Set Up Then the levennan turns the signal amber lamp, above the normal posi When setting up a route, the lever- lever back to its normal position. tion of the switch lever, is lighted man operates the switch levers to Sectional-route-release locking is in when the switch is locked in the position the switches for the track effect, so that the lock lights above normal position. A green lamp, line-up required. He then moves the switch levers, are extinguished as above the reverse position, is lighted signal lever (to left or right), which the rear of the train clears respective when the corresponding switch is closes a contact that completes a release sections. However, none of locked in the reverse position. In the route network circuit to energize a these lock lights is extinguished until center, above each switch lever, relay that causes a white indication the signal lever is placed normal.

When signal lever Is pushed an "exit" lamp is lighted on the diagram, then the lever is turned to clear the signal there is a red lamp which is lighted lamp to be lighted in the track line, When it is desirable to move a when electric locking is in effect to on the diagram, at the location where train into a section of track occu prevent operation of the switch, even the train will leave the interlocking pied by a preceding train, the lever- if the lever is thrown. There are 42 limits, by looking at the diagram to man operates the signal lever in the switch levers to control 45 switches, see this "exit" lamp lighted, the usual manner. Where a dwarf signal 19 slip switches, 10 movable-point leverman thus has a quick check to is involved, the restricting indication frogs and 3 derails. These switches, know that he has lined up the will be displayed if the first track slips, movable-point frogs and de switches properly for the route re section beyond the signal is unoccu rails are operated by a total of 77 quired. He then pushes the signal pied. If the first section beyond electro-pneumatic switch machines. lever. This action closes a circuit to dwarf signal is occupied or where The signal levers are in a row be to pick up a lever-repeater relay. pedestal signals are involved, the low the switch levers. Thirty-one This opens the stick-locking relay leverman must also push a spring- signal levers control 64 home signals. and places the route locking in effect, return pushbutton, located below the Each signal lever stands normally on which is indicated by lighting a red signal lever. This causes a stop-and- center, being thrown to the right 45 indication lamp over the center posi proceed indication to be displayed deg. to clear a northward signal, or tion of each of the levers for the on the pedestal signal, and a restrict to the left 45 deg. to clear a south- switches so locked, and clears the ing indication to be displayed on a

* '44l

1820' " 2800' Track and signal diagram of the new interlocking installed by the

312 RAILWAY SIGNALING and COMMUNICATIONS MAY, 1952 The relays for the "tower" are the plug-in type Rear of relay rack showing terminal power switch mounted in racks made of angle iron down showing rear of relay receptacles dwarf signal. When this call-on station tracks, and traffic-direction No. 3 on the track diagram, and cir pushbutton is operated, the lever- controls are provided. For each of cuits are established to permit the man must return the signal to stop the ten station tracks, there is a clearing of a southward signal lead while the train occupies the first check lever. These levers are in a ing to track No. 3, but not a north track section beyond the signal. group near the center of the panel ward signal leading to this track. Otherwise time locking becomes below the track diagram. The normal Having cleared the southward home effective. position of these levers corresponds signal, and after a southward train to the assigned direction of traffic has entered No. 3 station track and Traffic Direction for the track involved, that is, to the has stopped at the platform, there On some of the routes, the tracks left for southward tracks and to the could be an instance in which a have been laid out so that trains can right for northward tracks. When switching move would have to come approach at a fairly good speed, with lining a southward route on track in from the south end. In order to adequate distance to reduce speed No. 3, for example, the check lever clear the northward signal for a and stop after the locomotive enters for No. 3 track is thrown to the left. switch engine to enter the occupied the station. Complete track circuit A blue light is lighted in- the south station track, the check lever for that protection is provided through the arrow on the line representing track track would be moved to center posi

Pennsylvanla Railroad at in Philadelphia, Pa.

MAY, 1952 RAILWAY SIGNALING and COMMUNICATIONS 313 tion, and after an automatic time vane-frequency track relays on the motive enter each track circuit. relay— set at three minutes— com single-rail circuits. For each track re Code at 75 impulses per minute pletes its operation, (having started lay, there is a repeater relay located controls the Approach aspect, code operating when train entered sta in the relay room on the fifth floor of at 120 impulses controls the Ap tion track) movement can be made the station. proach-Medium aspect, and code at northward by operating the proper These repeater relays are biased 180 impulses controls the Clear as signal lever. The best aspect, under neutral relays; 800-ohm relays are pect, in the cab of a locomotive. No these circumstances, is Restricting. used for sections not involving code or steady energy causes the power-operated switches, and 2,000- Restricting aspect of the cab signal. Three Circuit Networks ohm relays for sections where power When an interlocking signal is dis This all-relay interlocking includes switches are involved. The 2,000- playing the Stop aspect, no code three basic circuit networks: (1) The ohm relays have a retarded pick-up exists in the track circuit for a dis lever-agreement network, in the of about 0.85 seconds at 12 volts, and tance of approximately 1,000 ft. im mediately in approach to that signal. This results in the cab signal chang ing from approach to restricting, Plug coupled re about 1,000 ft. in approach of a Stop lays are used In the sheet-metal signal. cases at switches and home signals Two-Arm Pedestal Signals All the signals on this interlocking are the position-light type. Many of the home signals are of the pedestal type, the upper lamp unit of these signals being about 7 ft. above the base of the rail. These pedestal sig-

"tower," checks through contacts on levers or lever-repeater relays to de termine that the levers of all switches and opposing or conflicting signals are in the proper position; (2) The The interior of a route check network, also in the sheet-metal case "tower," checks to determine that the with track relays, switches involved are actually in the code transmitters, position required and that opposing and transformers signals are in Stop position; and (3) The signal network insures that switches in the route are locked and that stick locking relay releases- checks track occupancy and is con provide additional protection against nals have two "arms," and, therefore, trolled through contacts of switch- momentary loss of shunt. Superim display a complete range of aspects, repeater relays to select the signal posed on these track circuits is code the same as a high signal. The back for the route being established. current which inductively controls ground on these pedestal signals is cab signaling apparatus on the loco only 16 in. wide, and the overall Track Circuits motives. This cab signal code current height is 4 ft.; therefore such a signal All tracks in this interlocking are is in service on the main approach can be located, with adequate clear equipped for electric propulsion, tracks and on track No. 3, No. 4, No. ance, between tracks spaced on 15-ft. using 11,000 volts, 25 cycle on over 5 and No. 6 through the station plat centers. An advantage is that such head trolley, with double-rail return forms. This coded cab signal energy a signal can be located exactly where on tracks arranged for cab signaling, is not normally fed on the rails. How required to be most effective, and to and single-rail return on all other ever, when a route is lined up, this utilize track length efficiently. tracks. Track circuits are operated coded cab signal energy feeds from The interlocking machine is on at 100 cycles a.c, using centrifugal the exit end to the entrance end of the fourth floor of the station build frequency track relays on the double- each track circuit, immediately, ing and the relay room is on the fifth rail circuits, and single-element, when the front wheels of the loco- floor directly above the machine.

314 RAILWAY SIGNALING and COMMUNICATIONS MAY, 1952 other similar terminals, the wire is No. 14 solid with %-t-in insulation. Approximately 210,000 ft. of wire was used in this relay room. This wire runs in troughs, made of %-in. asbestos boards, supported on frame works made of 94o-in. by lii by 1M angle-iron, bolted together. From the relay room the cables (going outdoors) extend down a ver tical concrete duct for approximately 194 ft. to basement level below ground line. These cables, 61 and 91 conductor, are No. 14 solid insulated wire. In this vertical duct, each cable is tied by marline ties to a X-in. stranded galvanized steel mes senger, which at the top is attached to heavy angle-iron cross beams. Panel on station platform for con From cable vaults in the basement trolling train starting Indicator the principal cables extend in under ground concrete ducts to manholes and instrument housings. From Twenty-two 61-conductor cables run there, buried cables extend to switch A train starting Indicator from the machine to the relay room. machines and signals. The gage of is mounted over each track A terminal board, built in the relay wire in these cables, for control cir room, has terminals arranged to cor cuits, is practically all No. 14. respond with the arrangement of the light, and after observing that pas terminals at the rear of the machine, Train Starting System sengers in his vicinity have boarded an exception being that there is As part of the interlocking project, the train, the flagman then goes to much more space between terminal a train-starting signal system was in the nearest post and pushes the blocks on the board in the relay stalled to save time by coordinated "flagman" button. This lights the room. Because of limited space on action of all persons concerned when yellow lamp in the indicators, above the board at rear of machine, and be trains are ready to depart. On several the track. The conductor observes cause of sharp turns and limited of the posts along the platforms, the indicator, then checks to see that space in ducts; special cable, with there is a panel having a lamp and passengers are loaded on the re No. 16 flexible wire and %4-in. insu several pushbuttons. Over each mainder of the train, and that mail lation, was used for the circuits be track, near the north and south end and baggage are all loaded; after tween the machine and the board of the platform, there is a special in which he goes to the nearest post in the relay room. Solderless connec dicator which has two 3M-in. lenses, and pushes the "Conductor" button, tors are used in terminating this one yellow and the other green, which lights the green light in the cable. visible in either direction. indicator over the track, so that both The relays in this relay room are About 15 seconds before the time the green and yellow lamps are the plug-in type, mounted on angle- that a train is due to depart, a station lighted, indicating to the train crew iron racks. Jumper wires, soldered to attendant presses a button in the that the train is ready to depart. With the fixed plug-in receptacle contacts, stairhead in the concourse, illumi the yellow and green indicator extend down to terminal boards on nating an amber light on the plat lights, and the amber light on the each rack. From these terminals to form panel. On receipt of this amber panel, illuminated, the conductor pushes button marked "Penn" Tower causing a light to be displayed in an indicator on the interlocking ma chine. If the signal for the train has not already been cleared, this "train starting" indicator is a reminder to the towerman to clear the signal. Fire Alarm System An automatic fire alarm system is in service in the relay room of this in terlocking. A small metal tube, about the size of No. 8 wire, is supported by a tight wire extending the length of the room above the relay racks. These tubes are spaced 8 to 10 ft. apart. The tubes contain gas under pressure. If a flame warms the tube, the gas expands and operates a pneumatic relay, thus sounding an alarm. This interlocking was planned and installed by signal forces of the Left— the front, and right — the rear of the terminal board In relay room .

MAY, 1952 RAILWAY SIGNALING and COMMUNICATIONS 315