ACCOMPLISHMENTS IN FREEWAY OPERATIONS OUTSIDE THE UNITED STATES

A SURVEY IS PRESENTED OF SYSTEMS THAT HAVE BEEN TRIED OR PROPOSED FOR RAMP, CORRIDOR, AND FREEWAY CONTROL IN WEST GERMANY, ENGLAND, JAPAN, ITALY, AND FRANCE. WEST GERMANY HAS BEEN EXPERIMENTING WITH VARIABLE- MESSAGE, REMOTE-CONTROLLED SIGNS AND SIGNALS ON A 20-MILE STRETCH OF THE MUNICH--SALZBURG AUTOBAHN TO CONTROL SPEED AND WARN OF ACCIDENTS AHEAD. SUCCESS IN THESE TRIALS HAS LED TO A DECISION TO DEPLOY THESE DEVICES ON OTHER HEAVILY TRAFFICKED SECTIONS OF THE AUTOBAHN AND TO EMPLOY DETECTORS TO PROMOTE MOE RATIONAL USE OF THE SIGNS TO INCREASE TRAFFIC FLOW. OTHER INVESTIGATIONS RELATE TO RAMP CONTROL, DISTRIBUTION OF TRAFIC OVER ALTERNATIVE ROUTES, AND USE OF ACOUSTIC SIGNAL TRANSMISSIONS TO INFLUENCE DRIVER, BEHAVIOR AND ROUTE SELECTION; THE LAST, A LOUD-SPEAKER SYSTEM, WOULD BE USED INITIALLY ONLY FOR EMERGENCY SITUATIONS. REMOTE-CONTROLLED SIGNS HAVE BEEN IN USE IN ENGLAND SINCE THE EARLY 1960'S LEADING IN 1966 TO THE DECISION TO EQUIP THE ENTIRE 1000-MILE MOTORWAY NETWORK WITH REMOTE-CONTROLLED SIGNALS TO DEAL WITH EMERGENCIES. THE MOTORIST IS INFORMED OF THE ACTION HE MUST TAKE (SPEED AND LANE). THE SYSTEM IS CONTROLLED BY COMPUTER. PROPOSED CHANGES IN SIGNALS AND MESSAGES ARE PRESENTED TO AN OPERATOR FOR DECISION. THE MAIN INPUTS ARE ROADSIDE TELEPHONES AND REGULARLY INTERROGATED LOOP DETECTORS. HARDWARE FOR THE SIGNAL AND COMPUTER SYSTEMS IS DESCRIBED. TABLES DESCRIBING THE BEFORE-AND-AFTER ACCIDENT HISTORY OF THE REMOTE-CONTROLLED SECTIONS ARE GIVEN. IN ADDITION TO ITS 90 MILES OF URBAN FREEWAYS, JAPAN HAS 479 MILES OF RURAL NETWORKS, ALL OF WHICH ARE EQUIPPED WITH VARIABLE-MESSAGE SIGNS TO DEAL WITH EMERGENCIES. BECAUSE OF THE CONCISENESS OF THE JAPANESE WRITTEN LANGUAGE, THE SIGNS CAN INFORM THE DRIVER NOT ONLY OF THE ACTION TO TAKE BUT ALSO THE REASON FOR ITS NECESSITY. THESE SIGNS ARE PART OF A SYSTEM COMPRISING EMERGENY TELEPHONES, VEHICLE DETECTORS, AND TELEVISION CAMERAS. JAPANESE TRAFFIC ENGINEERS ARE ALSO USING THE SYSTEM TO MAKE EXTENSIVE TRAFFIC FLOW SURVEYS WITH THE AIM OF KEEPING UNEXPECTED DELAY TIME BELOW A CERTAIN VALUE. WORK IN ITALY HAS CONCENTRATED ON TWO PROBLEMS: (1) SAFETY IN LONG TUNNELS, BY MEANS OF QUEUE DETECTION, TELEMETERING OF SIGNALS INDICATING THE PRESENCE OF QUEUES, AND CONTROL OF TUNNEL ENTRANCES BY TRAFFIC LIGHTS; AND (2) PREVENTION OF QUEUE FORMATION IN TUNNELS THAT ARE CLOSE TO TOLL BARRIERS. SIGNALS FROM LOOP DETECTORS ARE ANALYZED AUTOMATICALLY TO DETERMINE WHETHER THEY EXCEED A GIVEN TIME THRESHOLD. SLOWLY MOVING QUEUES ARE DEALT WITH BY SHORTENING THE THRESHOLD TIME OF A DETECTOR IMMEDIATELY AFTER LIGHT OPERATION AND RELEASE. THE INSTALLATION IS ALSO BEING USED FOR TRAFFIC FLOW STUDIES. OTHER SYSTEMS IN USE MONITOR CARBON MONOXIDE, VEHICLE SPACING, AND MAXIMUM SPEED. VARIABLE-MESSAGE SIGNS ARE REMOTELY AND AUTOMATICALLY CONTROLLED. CONSIDERABLE WORK HAS BEEN DEVOTED TO A STUDY OF APPLYING THE LIGHTHILL -WHITHAM MODEL TO THE PROBLEM OF FREEWAY CONTROL AND SURVEILLANCE. TWO RECENTLY CONSTRUCTED FREEWAYS SOUTH OF PARIS ARE PART OF A COMPLEX NETWORK THAT WAS SELECTED IN 1968, AS THE OBJECT OF A STUDY TO ENSURE OPTIMUM USE OF THE NETWORK UNDER ALL CONDITIONS. A COMPLETE SYSTEMS ANALYSIS OF THE NETWORK WAS MADE TO DEFINE A TRAFFIC CONTROL SYSTEM. A COMPUTERIZED SYSTEM WAS DEFINED WHOSE INSTALLATION IS EXPECTED TO TAKE PLACE IN PHASES. THE FIRST PHASE WAS TO BE IN OPERATION DURING 1971.

Media Info

  • Media Type: Print
  • Features: References; Tables;
  • Pagination: pp 9-25
  • Monograph Title: Accomplishments in freeway operations
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00226170
  • Record Type: Publication
  • ISBN: 0309019834
  • Report/Paper Numbers: HS-011 999
  • Files: TRIS, TRB
  • Created Date: Mar 20 1972 12:00AM