Control of overweight vehicle movements in New Zealand.

IN 1970 THE NEW ZEALAND NATIONAL ROADS BOARD (NRB), IN CO-OPERATION WITH OTHER ROAD CONTROLLING AUTHORITIES AND INTERESTED PARTIES, ADOPTED A COMPREHENSIVE AND UNIFORM POLICY FOR THE ISSUING OF OVERWEIGHT PERMITS. EACH MOVEMENT BY AN OVERWEIGHT VEHICLE IS CATEGORISED ACCORDING TO THE SEVERITY WITH WHICH ROAD PAVEMENTS AND BRIDGES ARE STRESSED, RESTRICTIONS BEING APPLIED ACCORDING TO THE MOVEMENT CATEGORY. SINCE ALL ROAD PAVEMENTS ARE GRADED TO REFLECT THEIR ABILITY TO CARRY OVERWEIGHT LOADS, THE MOVEMENT CATEGORY DEPENDS NOT ONLY ON THE AXLE WEIGHTS OF THE VEHICLE CONCERNED BUT ALSO ON THE GRADES OF PAVEMENT IT TRAVERSES. BRIDGE LOADING IS DETERMINED ON THE BASIS OF A SIMPLE RATING SYSTEM WHICH CAN BE USED BY CLERICAL STAFF. THE SYSTEM IS NECESSARILY CONSERVATIVE AND ONCE HIGHER LEVELS OF LOADING ARE REACHED, STRESSES MUST BE ASSESSED MORE ACCURATELY BY TECHNICAL STAFF. DEPENDING ON THE LEVEL OF STRESS CALCULATED EACH BRIDGE CROSSING WILL BE UNSUPERVISED, SUPERVISED OR NOT APPROVED. A SYSTEM INVOLVING THE RAPID COMPUTER ANALYSIS OF BRIDGE STRESSES HAS RECENTLY BEEN DEVELOPED, WHICH GREATLY REDUCES THE ADMINISTRATIVE EFFORT AND EASES THE RESTRICTIONS ON OVER-WEIGHT VEHICLE MOVEMENTS. (A). FOR THE COVERING ABSTRACT OF THE CONFERENCE PROCEEDINGS SEE IRRD ABSTRACT NO. 226354.