00730206

Component

https://doi.org/10.1177/0361198196152300105

https://scholar.google.co...IDIS&publication_year=1996

Safety issues affecting modern highway geometric design of roads in non-built-up areas are discussed. The status of knowledge of Safety Criteria I and II (achieving operating speed consistency and design consistency) for two-lane rural roads is briefly reviewed. Considerations for design consistency are also extended to multiple-lane rural and suburban road design to evaluate good, fair, and poor design levels for these road categories. Utilization ratios (n) for maximum permissible side friction factors are developed for different road categories, topography levels, and maximum and minimum superelevation rates. Relevant minimum radii for curve design are established and compared with present AASHTO values insofar as possible. Safety Criterion III (achieving driving dynamic consistency) is further developed, through which reliable and quantitative ranges between the side friction assumed and the actual friction demand at curved sites could be established. AASHTO's design policy is evaluated on the basis of Criteria II and III. The evaluation showed, for lower design speeds [30, 40, and 50 mph (48.3, 64.4, and 80.5 kph)], an unbalanced degree of curve and superelevation rate ranges, which lead to poor design practices from a safety viewpoint. By heeding the three safety criteria and the recommended side-friction utilization ratios, sound alignments can be established for the various design cases in future highway geometric design and redesign and for resurfacing, restoration, and rehabilitation strategies.

This paper appears in Transportation Research Record No. 1523, Geometric and Other General Design Issues.

English

p. 34-45

1996

Transportation Research Record

0309062217

Figures (9) ; References (37)

Alignment; Consistency; Curvature; Design speed; Driving; Friction; Geometric design; Highway curves; Highway design; Radius; Rural highways; Safety; Superelevation; Topography; Two lane highways

American Association of State Highway and Transportation Officials

Design consistency; Side friction

Design; Highways; Planning and Forecasting; Safety and Human Factors; I21: Planning of Transport Infrastructure; I82: Accidents and Transport Infrastructure

TRIS, TRB

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