Citation

Lamm R. Transp. Res. Rec. 1984; 960: 13-20.

Copyright

(Copyright © 1984, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

One of the main safety goals in developing new German Guidelines for the Design of Rural Highways was to overcome previous driving dynamic deficiencies and to enhance traffic safety by increasing friction supply wherever possible. The objectives of this paper are to discuss the German approach in determining new tangential and side friction factors with respect to design speed and to compare these values with those currently in use in the United States. The comparison showed that for design speeds greater than 80 km/h (50 mph), the maximum allowable tangential and side friction factors used in the United States are definitely higher than the German values. Accordingly, the computations for minimum stopping-sight distances and minimum radii of curve showed for all investigated cases and driving dynamic models smaller values in the United States than in Germany. Therefore, there is no doubt that, on the one hand, the American rural highway design is more economic but, on the other hand, the German values provide higher friction supply in critical driving situations. Finally, a preliminary study between road sections conducted according to the new German design guidelines and those with old horizontal and vertical alignment showed, on average, a 1.67 times lower accident rate for the redesigned road sections. This result is confirmed by a new research report for the Minister of Transportation of the Federal Republic of Germany, which will soon be published.

Language: en

Keywords

HIGHWAY ENGINEERING; DYNAMICS; HIGHWAY SYSTEMS - Skid Resistance; PAVEMENTS - Friction