Artículos científicos

TRADITIONALLY, THE GEOMETRIC DESIGN OF HORIZONTAL CURVES HAS BEEN PERFORMED IN ACCORDANCE WITH THE POINT MASS MODEL IN THE MAJORITY OF DESIGN REGULATIONS. HOWEVER, WE MAY ASK OURSELVES WHETHER THE TRADITIONAL DESIGN APPROACH CONTRIBUTES TO ROAD SAFETY. RESEARCH UNDERTAKEN IN AUSTRALIA, UNITED STATES AND CHILE HAS SHOWN THAT IN ROAD DESIGNS WITH AVERAGE AND LOW CATEGORIES THE SPEED OF OPERATION EXCEEDS THE SPEED OF DESIGN IN HORIZONTAL CURVES. GIVEN THIS FACT, WE ASK OURSELVES WHICH IS THE REAL SAFETY MARGIN OFFERED BY THE DESIGN OF THE CURVE AND HOW IS IT POSSIBLE TO ESTIMATE IT. IN THIS PAPER THE AUTHORS PROPOSE A NEW DESIGN APPROACH BASED ON THE 3-ZONE MODEL, WHICH INTEGRATES CONCEPTS OF FRICTION DEMAND, DESIGN FRICTION, REAL ROAD SURFACE FRICTION AND FRICTION THRESHOLDS IN THE DESIGN OF HORIZONTAL CURVES. THIS INTEGRATION IS PERFORMED UNDER A PROBABILISTIC APPROACH BASED ON THE RELIABILITY THEORY, WHICH ALLOWS US TO ESTIMATE THE SAFETY MARGIN OFFERED BY VARIOUS DESIGNS, RECOGNISING THAT THE SPEED OF OPERATION AND THE FRICTION ARE RANDOM VARIABLES, THUS EXPANDING THE SAFETY FACTOR CONCEPT TRADITIONALLY UTILISED IN ENGINEERING. THIS PAPER DEVELOPS THE CONCEPTS OF RELIABILITY AND THE WAY IN WHICH THEY ARE APPLIED IN THE 3-ZONE MODEL. THROUGH SIMULATION, WE OBTAIN THE RELATIONS BETWEEN THE GEOMETRY AND THE POINT IN THE DESIGN THAT MAXIMISES ITS RELIABILITY. FINALLY, WE PERFORM AN APPLICATION TO ILLUSTRATE THE METHOD DEVELOPED, CONSTITUTING AN ALTERNATIVE TO TRADITIONAL DESIGN METHODS THAT DELIVERS MORE CONCEPTUAL ELEMENTS THAT FOSTER AN ENHANCED DESIGN ANALYSIS.