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 Philadelphia Panel-type control machine uses thumb-type turn-and- Arsenal interlocking with the four- track line toward Baltimore 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 Pennsylvania 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 30th Street Station 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.