Unformatted text preview: The University of Texas at Austin Chandra Bhat
Dept of Civil, Architectural & Environmental Engineering Fall 2016 CE 321 Transportation Systems Homework Assignment No. 5
Roadway Characteristics and Design Date distributed: November 1, 2016
Due date: November 8, 2016 l. A highway horizontal curve has been designed for 60 mph with a superelevation rate of
0.10 feet per foot. The safe coefﬁcient of sliding friction fside is related to the speed V (in
mph) with which a vehicle is negotiating the horizontal curve by the formula fside : 0.19 ~ 0.001V.) a) Determine the degree of curvature of this curve b) Ten years after this curve has been laid out, the pavement surface is overlaid and
in doing so the superelevation rate has been altered to 0.08. What is the maximum
safe operating speed on this curve after the overlay? 2. A horizontal curve on Lakeshore Drive in Chicago had a radius of 306.33 feet, which
restricted the maximum speed on this section of the road to only 60% of the design speed
of the highway. The need to suddenly reduce speed at this section caused several
accidents. The local transportation authority decided. a few years back to improve the
curve so that the maximum speed on the section would be equal to the design speed of g
the highway. What had to be the minimum radius of the improved curve? Assume the 1
same relationship between the coefficient of side friction and speed on the horizontal :
curve as in the previous question. Assume the superelevation rate of the old and
improved curves to be 0.08. ...
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 Fall '08
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 Friction, Road, transportation systems, horizontal curve, Austin Chandra Bhat

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