Average speed and traffic density as a measure of road capacity

MEASUREMENT OF THE UTILITY OF A HIGHWAY IS ITS ABILITY TO FACILITATE TRAFFIC. THE COMPARATIVE UTILITY OF VARIOUS ROAD TYPES MAY THEREFORE BE DETERMINED FROM AN ACCURATE MEASUREMENT OF THE USUAL SPEEDS OF MOTOR VEHICLES AND THE DENSITY OF TRAFFIC ON THE ROADWAYS CONSIDERED. THE AVERAGE SPEEDS RECORDED IN THE INVESTIGATION WERE 47.8 MILES AN HOUR FOR PASSENGER CARS ON PAVEMENT, 43.3 MILES AN HOUR ON TREATED-TYPE A, 37.1 MILES AN HOUR ON TREATED-TYPE B, AND 32.6 MILES AN HOUR ON UNTREATED LOOSE-GRAVEL. THE CORRESPONDING AVERAGE SPEEDS FOR TRUCKS OR HEAVY COMMERCIAL VEHICLES WERE 37.9 MILES PER HOUR ON PAVEMENT, 32.5 ON TYPE A, 30.9 ON TYPE B, AND 28.2 FOR LOOSE GRAVEL. FROM THESE AVERAGE SPEEDS THE RELATIVE CAPACITIES WERE DEDUCED TO BE: FOR CARS, GRAVEL 1, TREATED SURFACE A 1.33, TREATED SURFACE B 1.15, PAVEMENT 1.47; FOR TRUCKS, GRAVEL 1, SURFACE A 1.30, SURFACE B 1.23, PAVEMENT 1.51. THE RELATIVE VALUES OF TIME ON THE VARIOUS SURFACES ARE ALSO DISCUSSED. /AUTHOR/