ELECTRONICS RUNS THE SHOW IN BAY AREA TRANSIT SYSTEM

THE BAY AREA RAPID TRANSIT (BART) SYSTEM IS AN URBAN RAPID TRANSIT SYSTEM DESIGNED TO RELIEVE HIGHWAY CONGESTION. THE SYSTEM WILL INCLUDE 33 PASSENGER STATIONS AND 75 MILES OF DOUBLE-TRACK RAILROAD, BELOW GROUND AND ABOVE, IN SAN FRANCISCO, ALAMEDA, AND CONTRA COSTA COUNTIES. TO COMPETE WITH AUTOMOBILES, BART CALLED FOR AN AVERAGE SPEED OF 50 MPH, INCLUDING 20-SECOND STATION STOPS. AT TIMES, HEADWAY WILL BE ONLY 90 SECONDS FOR TRAINS RUNNING BETWEEN STATIONS AT 80 MPH, WITH ROUTES CONVERGING AND DIVERGING. THE DEGREE OF CONTROL NEEDED FOR SAFETY UNDER THESE CONDITIONS WILL BE PROVIDED BY AN AUTOMATIC TRAIN CONTROL SYSTEM. THE SYSTEM DEVELOPED BY WESTINGHOUSE ELECTRIC CORP. USES A CENTRAL COMPUTER WITH A SPECIAL-PURPOSE COMPUTER IN EACH HEAD-END CAR TO PICK UP SIGNALS FROM WAYSIDE EQUIPMENT. MAJOR COST- REDUCING FACTORS IN THE SYSTEM WERE THE DESIGN OF A MULTIPLEX DIGITAL SIGNAL SYSTEM. THE WESTINGHOUSE SYSTEM IS DESCRIBED. THE SYSTEM PERFORMS TWO DUTIES AT ALL TIMES: (1) TRAIN PROTECTION BY SPEED CONTROL BETWEEN STATIONS, AND (2) DECELERATION, BY ANOTHER CONTROL PROGRAM SUPERIMPOSED AT STATION APPROACHES, TO STOP THE TRAIN WITHIN 6 INCHES OF TARGET AT THE PLATFORM. THE TRAIN DOORS THEN OPEN AUTOMATICALLY FOR A PERIOD FIXED BY THE CENTRAL COMPUTER'S SCHEDULE-CONTROL LOOP. THE YARD DESIGN SYSTEM DESIGNED BY PHILCO-FORD AUTOMATICALLY TAKES OVER WHEN THE TRAIN-CONTROL COMPUTER SWITCHES A TRAIN FROM THE MAIN LINE TO A TRANSFER TRACK. A COMPUTER OVERSEES ALL STEPS OF THE YARD OPERATION. COST OF THIS SYSTEM IS KEPT DOWN BY THE USE OF SOLID-STATE FAILSAFE LOGIC INSTEAD OF CONVENTIONAL VITAL RELAYS FOR ALL SWITCHING EXCEPT FROM THE TRANSFER TRACK. A TYPICAL LOGIC MODULE IS THE DUAL JK FLIP-FLOP, BASED ON AEROSPACE TECHNOLOGY, THAT REDUCES THE SYSTEM TO HALF THE COST AND ONE-THIRD THE SIZE OF THE CONVENTIONAL RELAY SYSTEM IT REPLACES. THE AUTOMATIC YARD CONTROL SYSTEM IS DESCRIBED AS WELL AS A MECHANIZED FARE COLLECTION SYSTEM DEVELOPED BY IBM. SPECIFICATIONS FOR THE POWER SUPPLY AND TRAIN PROPULSION SYSTEMS CALL FOR: (1) FOUR 150-HP DC DRIVE MOTORS PER CAR, WITH SOLID-STATE CHOPPER CONTROL, (2) FOUR COLLECTOR SHOES PER CAR, CONTACTING A 1000-V DC RAIL, AND (3) A COMPOSITE CONTACT RAIL OF STEEL AND ALUMINUM, WITH NEGATIVE RETURN THROUGH RUNNING RAILS. A NEW COMPOSITE CONTACT RAIL AND A LIGHTWEIGHT COLLECTOR SHOE PROVIDE BETTER POWER TRANSMISSION TO A HIGH-SPEED VEHICLE AT MUCH LESS COST THAN THE CONVENTIONAL EQUIPMENT. THE NEW RAIL IS A COMPOSITE STEEL AND ALUMINUM DESIGN DEVELOPED BY KAISER ALUMINUM, WITH A PLYWOOD COVER ENCAPSULATED IN FIBER GLASS.

  • Supplemental Notes:
    • Vol 39, No 21, PP 56-65, 4 FIG, 10 PHOT
  • Publication Date: 1968-10-7

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  • Accession Number: 00241222
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 2 1994 12:00AM