RAMP CONTROL ON FREEWAYS IN CALIFORNIA

THREE FREEWAY RAMP CONTROL PROJECTS OPERATING IN CALIFORNIA ARE DESCRIBED. TRAFFIC VOLUME ON THE HARBOR FREEWAY IN LOS ANGELES IS ABOUT 190,000 VEHICLES PER DAY. THE CONTROL SECTION IS 5 MILES LONG AND INCLUDES SIX ON- RAMPS. FIVE RAMPS ARE CONTROLLED BY PREPORGRAMMED TRAFFIC SIGNALS AND ONE RAMP IS CLOSED DURING THE PEAK PERIOD. DURING THE REST OF THE DAY AND NIGHT THE SIGNALS REMAIN GREEN. FREEWAY SPEEDS HAVE INCREASED FROM ABOUT 20 MPH TO ABOUT 40 MPH. FREEWAY USERS ARE SAVING ABOUT 1000 VEHICLE HOURS PER DAY AGAINST A LOSS, OR INCREASED TRAVEL TIME, FOR DIVERTED OR DELAYED RAMP TRAFFIC OF ABOUT 130 VEHICLE HOURS. THE EFFECT OF THE ADDED LOAD ON STREETS IS TOO SMALL TO NOTICE. CAPACITY WAS NOT INCREASED, BUT THROUGHPUT UPSTREAM OF BOTTLENECKS WAS INCREASED. UNUSUAL TECHNIQUES EMPLOYED ARE: (1) PREFERENTIAL TREATMENT FOR BUSES IN THAT THEY ARE ALLOWED TO BYPASS RAMP QUEUES AND TO MAKE LEFT TURNS WHERE OTHER TRAFFIC IS NOT, (2) STORAGE OF QUEUED VEHICLES ON A FRONTAGE ROAD WHICH IS CARRIED BACK ACROSS AN INTERVENING MAJOR THOROUGHFARE BY TIMING THE INTERSECTION SIGNAL SO THAT THE INTERSECTION REMAINS CLEAR, AND (3) TWO-ABREAST RELEASE OF VEHICLES AT THE RAMP SIGNAL AT ONE LOCATION INCREASES STORAGE ROOM AND MAKES POSSIBLE HIGH METERING RATES. THE HOLLYWOOD FREEWAY CONSISTS OF ONE METERING RATE AND ONE RAMP THAT IS CLOSED BY BARRICADES DURING THE PEAK PERIOD. THE METERED RAMP IS OPERATED BY A PRETIMED SIGNAL. TRAVEL TIME SAVINGS ARE ABOUT 450 VEHICLE HOURS PER DAY, CONSISTING OF 500 HOURS SAVINGS FOR FREEWAY USERS UPSTREAM OF THE BOTTLENECK LESS 50 HOURS FOR LOSS TO DIVERTED OR DELAYED RAMP TRAFFIC. FOUR RAMPS ON 3.2 MILES OF A 4-LANE FREEWAY IN CHULA VISTA ARE BEING CONTROLLED. PEAK-HOUR INPUT FROM THESE FOUR RAMPS WAS REDUCED BY 580 VEHICLES, AND INPUT TO THE MAINLINE UPSTREAM OF THE CONTROL SECTION WAS INCREASED BY 540 VEHICLES. SPEED ON THE FREEWAY INCREASED FROM 26 MPH TO 43 MPH FOR THE HIGHER VOLUME.

• Record URL:
  • http://onlinepubs.trb.org/Onlinepubs/hrr/1969/279/279-012.pdf
• Supplemental Notes:
  • Paper sponsored by Committee on Freeway Operations. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
• Authors:
  • Russell, G L
• Publication Date: 1969

Media Info

• Media Type: Print
• Pagination: pp 153-154
• Monograph Title: Freeway traffic characteristics and control
• Serial:
  • Highway Research Record
  • Issue Number: 279
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Freeway operations; Handling and storage; Interchange ramps; Queuing; Storage facilities; Traffic control; Traffic signal control systems; Traffic speed; Traffic volume; Travel time
• Old TRIS Terms: Freeway ramps
• Subject Areas: Freight Transportation; Highways; Operations and Traffic Management; Terminals and Facilities;

Filing Info

• Accession Number: 00225544
• Record Type: Publication
• Report/Paper Numbers: Paper No 1
• Files: TRIS, TRB
• Created Date: Oct 21 1994 12:00AM