BARRIER-CURB REDIRECTION EFFECTIVENESS

BARRIER CURBS ARE USED EXTENSIVELY ALONG SOME URBAN FREEWAYS AND IN FRONT OF BRIDGE RAILS. HERETOFORE, THE REDIRECTIVE EFFECTIVENESS OF SUCH CURBS HAS NEVER BEEN QUANTIFIED. A METHOD DEVELOPED FOR THIS PURPOSE MAKES IT POSSIBLE TO DEFINE THE REDIRECTIVE EFFECTIVENESS OF A GIVEN CURB AT ANY PARTICULAR INSTALLATION SITE. RESEARCH HAS SHOWN THAT BARRIER-CURB REDIRECTION PERFORMANCE CAN BE DESCRIBED IN TERMS OF A LIMITING CHARACTERISTIC VELOCITY THAT IS THE COMPONENT OF VEHICLE VELOCITY NORMAL TO THE CURB FACE. THIS BOUNDARY AND REPRESENTATIVE ON-SITE DISTRIBUTIONS OF VEHICLE SPEED AND RANOFF-THE-ROAD ANGLE CAN BE USED TO COMPUTE A MEASURE OF CURB REDIRECTION EFFECTIVENESS. THIS IS ACCOMPLISHED BY INTEGRATING OVER THE 2 DISTRIBUTIONS WITH INTEGRATION LIMITS SUPPLIED BY THE REDIRECTION BOUNDARY. TWO BARRIER CURB CROSS SECTIONS ARE EVALUATED BY USING SPEED AND ANGLE DATA. THE BELGAIN TRIEF CURB IS SHOWN TO BE EFFECTIVE IN REDIRECTING 27.4 PERCENT OF THE EXPECTED POPULATION OF IMPACTING VEHICLES. A MORE EFFICIENT BARRIER CURB, DEVELOPED IN WEST GERMANY, IS SHOWN TO REDIRECT 70.4 PERCENT OF THE SAME POPULATION. IN LIGHT OF THESE RESULTS AND BECAUSE CURB IMPACTS PRODUCE LITTLE VEHICLE DAMAGE, IT IS RECOMMENDED THAT MORE OPTIMUM BARRIER CURBS BE DEVELOPED. THEIR USE, WHERE APPROPRIATE, WOULD BE IN PLACE OF OR IN COMBINATION WITH GUARDRAILS. /AUTHOR/