TRAFFIC FLOW AT THE EXITS OF GRADE-SEPARATED JUNCTIONS HAVING A DECREASE IN NUMBER OF LANES (CONTROL MEASUREMENTS)

UNTERSUCHUNG DES VERKEHRSABLAUFS AN AUSFAHRTEN VON PLANFREIEN KNOTENPUNKTEN MIT SPURSUBTRAKTION (KONTROLLMESSUNGEN)

PREVIOUS WORK RESULTED IN A CAPACITY MODEL FOR DESIGNING EXITS WHICH HAD A REDUCTION IN NUMBER OF LANES. THIS MODEL WAS ONLY VALID FOR THE GEOMETRIC CONDITIONS AT THE PLACE WHERE THE STUDY WAS UNDERTAKEN, WHERE THE SUBTRACTED LANE RAN INTO THE RIGHT-HAND LANE ON THE RAMP, AND THE LEFT-HAND LANE ON THE RAMP BEGAN AT THE LEVEL OF THE ISLAND PEAK (OLD FORM OF LANE SUBTRACTION). THE RESULTS SHOWED THAT IT WAS POSSIBLE THAT THE 500 M LONG MERGING OUT LANE (WITH THE SUBTRACTED LANE RUNNING INTO THE LEFT-HAND LANE ON THE RAMP), PROVIDED FOR IN SPECIFICATION RAL-K-2, COULD BE ELIMINATED, WHICH WOULD RESULT IN GREAT SAVINGS. THIS QUESTION COULD ONLY BE ANSWERED IF SUPPLEMENTARY CONTROL MEASUREMENTS WERE UNDERTAKEN ON LANE REDUCTIONS WHERE THERE WERE MERGING OUT LANES. THIS WAS POSSIBLE ON THE OPENING OF THE HAMBURG ELBE TUNNEL, SINCE THE ONLY EXISTING LANE SUBTRACTION WITH A MERGING OUT LANE IN THE FEDERAL REPUBLIC OF GERMANY - THE MOTORWAY TRIANGLE AT HAMBURG-NW, IS NOW TRAFFICKED BY A LARGE NUMBER OF DRIVERS WHO KNOW THE AREA AND VERY HEAVY TRAFFIC STREAMS. THEREFORE CONTROL MEASUREMENTS ARE TO BE MADE TO VERIFY OR REFUTE THE DESIGN PROVIDED FOR IN RAL-K-2.