FREEWAY RAMP CONTROL--WHAT IT CAN AND CANNOT DO
CONGESTION (STOP-AND-GO DRIVING) OCCURS REGULARLY DURING PEAKS ON CERTAIN SECTIONS OF THE FREEWAY SYSTEM. IT IS CAUSED BY TRAFFIC DEMANDS EXCEEDING CAPACITY AT A FEW BOTTLENECK SECTIONS. FLOW THROUGH THE BOTTLENECK IS SMOOTH: UP-STREAM OF THE BOTTLENECK, THERE ARE QUEUES WHICH CAUSE THE STOP-AND-GO NATURE OF THE STREAM. SOME THEORY OF TRAFFIC FLOW IS GIVEN (VERY QUALITATIVELY) TO SHOW HOW CERTAIN FIGURES OF MERIT ARE IMPROVED. THE MOST IMPORTANT CONCLUSIONS WITH REGARD TO RAMP CONTROL ARE: (1) CAPACITY OF A BOTTLENECK DOES NOT INCREASE WITH RAMP CONTROL. (2) SLIGHT SACRIFICES IN OPTIMUM FREEWAY CONTROL THAT SOMETIMES ARE MADE TO INSURE GOOD STREET OPERATION ARE NOT CRITICAL. (3) RANDOM MERGING OF SINGLE VEHICLES OR SMALL PLATOONS IS SATISFACTORY AT USUAL RAMPS. (4) IT IS BETTER TO OPERATE AT SLIGHTLY BELOW CAPACITY TO ALLOW FOR RECOVERY FROM INCIDENTS WHICH ALWAYS OCCUR. (5) SHARP REDUCTIONS IN METERING RATES THAT WOULD BE REQUIRED TO DISSIPATE CONGESTION ARE USUALLY NOT POSSIBLE BECAUSE OF THE SEVERE CONGESTION THAT WOULD RESULT ON SURFACE STREETS. (6) UNLESS GOOD INFORMATION CAN BE GIVEN TO DRIVERS APPROACHING METERED RAMPS, SHARP FLUCTUATIONS OF METERING RATES ARE NOT ADVISABLE. /BPR/
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Supplemental Notes:
- Vol 19, pp 14-21
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Authors:
- NEWMAN, L
- DUNNET, A
- Meis, G J
- Publication Date: 1969-6
Media Info
Subject/Index Terms
- TRT Terms: Bottlenecks; Highway capacity; Interchange ramps; Merging traffic; Traffic congestion; Traffic control
- Old TRIS Terms: Freeway ramps; Metering; Traffic control systems
- Subject Areas: Highways; Operations and Traffic Management;
Filing Info
- Accession Number: 00225778
- Record Type: Publication
- Source Agency: Traffic Systems Reviews & Abstracts
- Files: TRIS
- Created Date: Jul 27 1970 12:00AM