00818861

Component

https://doi.org/10.3141/1751-05

http://scholar.google.com...sapi&publication_year=2001

On and off ramps act as interfaces between freeways and the surface street network (nonfreeway highways) and in effect should provide a smooth and safe transition from one facility to another. The speed behavior of passenger cars at minor-interchange on and off ramps with unusual curved arrangements is analyzed in depth for the first time. Vehicle speed data were collected at 20 on and off ramps in Greece that have a variety of geometric features. Regression analyses were applied to investigate the variables affecting operating speed, expressed by the 85th percentile speed (V sub 85). The best models resulted in coefficients of determination of nearly 0.75, indicating that operating speed is influenced by curvature change rate and superelevation rate. Comparison of the "Greek speed profile" with those of Australia, Austria, Germany, South Africa, and the United States proved that for on and off ramps it very closely approximates the values of Australia, Austria, and Germany. Austria is the only country using V sub 85 to determine ramp geometrics. The differences between the Greek V sub 85 and the speed values recommended by the German guidelines are considered small, ranging from 6 to 9 km/h for on ramps and -1.5 up to -4 km/h for off ramps. The analysis produced regression models that will provide designers with a tool to estimate the operating speed during the design process.

This paper appears in Transportation Research Record No. 1751, Geometric Design and the Effects on Traffic Operations 2001.

English

p. 35-43

2001

Transportation Research Record

0309072123

Figures (5) ; References (11) ; Tables (7)

85th percentile speed; Behavior; Curvature; Drivers; Field studies; Geometric design; Interchanges; Off ramps; On ramps; Operating speed; Regression analysis; Superelevation

Australia; Austria; Germany; Greece; South Africa; United States

Data and Information Technology; Design; Highways; Planning and Forecasting; Safety and Human Factors; I21: Planning of Transport Infrastructure

TRIS, TRB

Oct 18 2001 12:00AM

• APPLICATION OF ARTIFICIAL NEURAL NETWORKS TO PREDICT SPEEDS ON TWO-LANE RURAL HIGHWAYS
• CONTROLS FOR HORIZONTAL CURVE DESIGN
• DESIGN FACTORS THAT AFFECT DRIVER SPEED ON SUBURBAN STREETS
• GEOMETRIC DESIGN AND SAFETY ASPECTS OF ROUNDABOUTS
• GUIDELINES FOR OPPOSING LEFT-TURN LANE-LINE WIDTHS
• OPERATING SPEED PREDICTION ON CREST VERTICAL CURVES OF RURAL TWO-LANE HIGHWAYS IN NEBRASKA
• OPERATIONAL EVALUATION OF FREEWAY RAMP DESIGN
• SAFETY EFFECT OF ROUNDABOUT CONVERSIONS IN THE UNITED STATES: EMPIRICAL BAYES OBSERVATIONAL BEFORE-AFTER STUDY
• SPEED PREDICTION MODELS FOR TRUCKS ON TWO-LANE RURAL HIGHWAYS
• TRAVEL TIME COMPARISONS BETWEEN SEVEN UNCONVENTIONAL ARTERIAL INTERSECTION DESIGNS