Citation

Harwood DW, Mason Jr. JM. Transp. Res. Rec. 1994; 1445: 22-33.

Copyright

(Copyright © 1994, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

The adequacy of the 1990 AASHTO geometric design policy for safely accommodating both passenger cars and trucks on horizontal curves is evaluated. The evaluation includes both the high-speed or open-highway horizontal curve design criteria in AASHTO Green Book Table III-6 and the low-speed design criteria for intersections and turning roadways in AASHTO Green Book Table III-17. The evaluation of current horizontal curve design policy is conducted by means of a sensitivity analysis that evaluates the margin of safety against vehicle skidding and rollover for both passenger cars and trucks traveling at the design speed on minimum-radius curves designed in accordance with AASHTO policy. It is concluded that current AASHTO horizontal curve design policy for rural highways and high-speed urban streets in Green Book Table III-6 provides an adequate margin of safety against both skidding and rollover as long as vehicles do not exceed the design speed of the curve. However under nearly worst-case conditions, skidding and rollover can occur on a horizontal curve, particularly at lower design speeds, if vehicles exceed the design speed by only a small amount. This finding suggests the importance of selecting a realistic horizontal curve design speed that will not be exceeded by substantial portions of the traffic stream. The AASHTO horizontal curve design criteria for intersections and turning roadways and low-speed urban streets, presented in Green Book Tables III-16 and III-17, are generally adequate for passenger cars that do not exceed the design speed, but may not be adequate for all trucks.

Language: en

Keywords

Acceleration; Accident prevention; Automobiles; Intersections; Speed; Trucks; Sensitivity analysis; Standards; Skidding; Curves (road); Highway systems; Structural design