Détail de la notice
Titre du Document
Determining critical length of grade for geometric design of vertical alignments
Auteur(s)
TORBIC Darren J. ; HARWOOD Douglas W. ; RICHARD Karen R. ; ...
Résumé
In the 2001 Green Book, critical length of grade is generally defined as the length of grade that would produce a speed reduction of 15 km/h (10 mph) for a 120-kg/kW (200-lb/hp) truck. The Green Book does not provide an appropriate tool for highway engineers to calculate critical length of grade for locations where a truck with a weight/power ratio other than 120 kg/kW (200 lb/hp) is appropriate. Research was conducted to determine the distribution of truck weight/power ratios in the current truck fleet in several regions of the United States. The results suggest that, for design purposes, a truck with a weight/power ratio of 102 to 108 kg/kW (170 to 180 lb/hp) would be appropriate for freeways in California and Colorado, although a weight/power ratio of 126 kg/ kW (210 lb/hp) would be more appropriate in Pennsylvania. For two-lane highways, a 108-kg/kW (180-lb/hp) design vehicle may be appropriate in Colorado, although less powerful design vehicles in the range of 150 to 168 kg/kW (250 to 280 lb/hp) may be appropriate for California and Pennsylvania. A truck speed profile model also was developed that enables highway designers to calculate the speed profile of trucks with any given weight/power ratio and for any given vertical alignment. This design tool will improve the ability to calculate critical length of grades for any situation.
Editeur
National Research Council
Identifiant
ISSN : 0361-1981 CODEN : TRREDM
Source
Transportation research record A. 2004, n° 1881, pp. 36-45 [10 pages] [bibl. : 6 ref.]
Langue
Anglais
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