and that the elevation of the intersection is 1010.69 feet. (a) What is the equation for the vertical curve described above? Don't round the coefficients. y =
When a road is being built, it usually has straight sections, all with the same grade, that must be linked to each other by curves. (By this we mean curves up and down rather than side to side, which would be another matter.) It's important that as the road changes from one grade to another, the rate of change of grade between the two be constant.† The curve linking one grade to another grade is called a vertical curve.
Surveyors mark distances by means of stations that are 100 feet apart. To link a straight grade of
to a straight grade of
the elevations of the stations are given by
g2 − g1 |
2L |
g1L |
2 |
Here y is the elevation of the vertical curve in feet,
and
are percents, L is the length of the vertical curve in hundreds of feet, x is the number of the station, and E is the elevation in feet of the intersection where the two grades would meet. (See the figure shown below.) The station
is the very beginning of the vertical curve, so the station
lies where the straight section with grade
meets the vertical curve. The last station of the vertical curve is
which lies where the vertical curve meets the straight section with grade
Assume that the vertical curve you want to design goes over a slight rise, joining a straight section of grade 1.33% to a straight section of grade
Assume that the length of the curve is to be 500 feet (so
and that the elevation of the intersection is 1010.69 feet.
(b) What are the elevations of the stations for the vertical curve? (Round your answers to two decimal places.)
first station | ft |
second station | ft |
third station | ft |
fourth station | ft |
fifth station | ft |
last station | ft |
(c) Where is the highest point of the road on the vertical curve? (Give the distance along the vertical curve and the elevation. Round your answers to two decimal places.)
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