00741916

Component

https://doi.org/10.3141/1579-11

http://scholar.google.com...mbro&publication_year=1997

Free-flow speeds were collected at both a control section and a curve section at 14 suburban sites with horizontal curves and 10 suburban sites with vertical curves. The scatter plots of the 85th percentile speed versus approach density indicate that when the approach density is between 3 and 15 approaches per km, approach density does not influence speed. Regression analysis indicated that the curve radius for horizontal curves and the inferred design speed for vertical curves can be used to predict the 85th percentile speed on curves for vehicles on the outside lane of a four-lane divided suburban arterial. For horizontal-curve sites, a curvilinear relationship exists between curve radius and the 85th percentile speed. A linear relationship provided the best fit between the inferred design speed and the 85th percentile speed for the vertical curve sites. For the horizontal and vertical curve sites, the speed at which 85th percentile speed becomes less than the inferred design speed is lower for suburban arterials than for rural highways. Drivers on suburban horizontal curves operate at speeds greater than the inferred design speed for curves designed for speeds of 70 kph or less, whereas on rural, two-lane roadways, drivers operate at speeds greater than the inferred design speed for curves designed for speeds of 90 kph or less. For vertical curves, the speeds at which drivers operate greater than the inferred design speed are 90 kph for suburban arterials and 105 kph for rural highways. These results are within 12 kph of the observed 85th percentile speeds on nearby control sections (approximately 80 kph for suburban arterials and 100 kph on rural highways).

This paper appears in Transportation Research Record No. 1579, Geometric Design and Its Effects on Operations.

English

p. 89-96

1997

Transportation Research Record

030906158X

Figures (5) ; References (6) ; Tables (3)

85th percentile speed; Alternatives analysis; Arterial highways; Curvature; Curves (Geometry); Design speed; Operating speed; Radius; Regression analysis; Rural highways; Suburbs

Horizontal curvature; Vertical curvature

Data and Information Technology; Design; Highways; Operations and Traffic Management; Planning and Forecasting; I21: Planning of Transport Infrastructure; I71: Traffic Theory

TRIS, TRB, ATRI

Oct 6 1997 12:00AM

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