CE 318 HIGHWAY ENGINEERING
Superelevation (SG-7)
Name: ________________________
Please complete all of your calculations on engineering paper and fill in the answers in
the spaces provided in the tables below.
1) A stretch of U.S. Highway 56 near Bald Knob curves to the right to avoid an area,
which contains American Indian burial grounds. U.S. Highway 56 is a 4-lane
undivided highway with 12’ lanes and 2% cross slopes in the normal crown section.
The degree of curvature of the highway is 3º 00’ and the PI station is located at 843 +
00. The deflection angle at the PI is 30º 00’. The design speed of the highway is 60
mph with a posted speed limit of 55 mph. The Arkansas Highway Department
recommends an erequired = 0.068’/’ and a 270’ long transition length from the normal
crown section to the point where the roadway will be fully superelevated. Assume
that the transition length will be equally divided before and after the PC of the curve.
Compute the superelevation rates as required in the table shown below:
STATION Superelevation
837 + 00 Lt.
Rt.
838 + 00 Lt.
Rt.
839 + 00 Lt.
Rt.
2) On a section of a four-lane undivided highway, a 2,500-foot radius horizontal curve
curves to the left to avoid a nearby cemetery. The length of the horizontal curve is
1500 feet and the PC is at STA 115 + 00. The vertical alignment consists of a 2000-
foot vertical curve joining a –4% grade and a +5% grade. The PVI is at STA 120 +
00 and has an elevation of 350.00 feet. Using a required superelevation rate of 3.8%
and a transition length of 137 feet, compute the superelevation for the roadway and
edge of pavement elevations at the stations listed below. Assume a normal crown
section with 0.02 feet per foot cross slope. Assume 12-foot lane widths.
STATION Superelevation Edge of Pavement Elevation
115 + 50 (Left)
115 + 50 (Right)
116 + 00 (Left)
116 + 00 (Right)
