AN EVALUATION OF RAMP CONTROL ON THE HARBOR FREEWAY IN LOS ANGELES

Abstract

A RAMP CONTROL PROJECT IS DESCRIBED ON THE 8-LANE HARBOR FREEWAY IN LOS ANGELES. CONGESTION OCCURRED EACH WEEKDAY IN THE 4 OUTBOUND LANES DURING THE EVENING PEAK PERIOD, WHILE THE ADJACENT PARALLEL STREETS WERE RELATIVELY UNCROWDED. THE CONTROL PROJECT IS DESIGNED TO REDUCE TOTAL TRAVEL TIME THROUGH THE FREEWAY CORRIDOR BY METERING 5 ON-RAMPS AND CLOSING 1 RAMP IN A 5-MILE SECTION DURING THE PEAK PERIOD. SOME UNUSUAL TECHNIQUES ARE BEING EMPLOYED: BUSES ARE ALLOWED TO BYPASS RAMP QUEUES AND TO MAKE LEFT TURNS WHERE OTHER TRAFFIC CANNOT; STORAGE OF QUEUED VEHICLES ON A FRONTAGE ROAD IS CARRIED BACK ACROSS AN INTERVENING MAJOR THOROUGHFARE BY TIMING THE INTERSECTION SIGNAL SO THAT THE INTERSECTION ITSELF REMAINS CLEAR; AND, AT ONE LOCATION, STORAGE ROOM IS INCREASED AND HIGH METERING RATES ARE MADE POSSIBLE BY THE RELEASE OF VEHICLES 2-ABREAST AT THE RAMP SIGNAL. RESULTS SHOW THAT FREEWAY USERS ARE SAVING ABOUT 1,000 VEHICLE-HOURS PER DAY AGAINST A LOSS, OR INCREASED TRAVEL TIME FOR DIVERTED OR DELAYED RAMP TRAFFIC, OF ABOUT 130 VEHICLE-HOURS. /AUTHOR/