> Transportation engineering textbook.pdf EXAMPLE 3.1 OLUTION Open w VERTICAL CURVE STATIONS AND ELEVATIONS A 600-ft equal-tangent sag vertical curve has the PVC at station 170+ 00 and elevation 1000 ft. The initial grade is -3.5% and the final grade is +0.5%. Determine the stationing and elevation of the PVI, the PVT, and the lowest point on the curve.

Structural Analysis
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ISBN:9781337630931
Author:KASSIMALI, Aslam.
Publisher:KASSIMALI, Aslam.
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Transportation engineering textbook.pdf
EXAMPLE 3.1
SOLUTION
Chapter 3
VERTICAL CURVE STATIONS AND ELEVATIONS
A 600-ft equal-tangent sag vertical curve has the PVC at station 170+ 00 and elevation
1000 ft. The initial grade is -3.5% and the final grade is +0.5%. Determine the stationing
and elevation of the PVI, the PVT, and the lowest point on the curve.
1000-3.5 ft/station X (3 stations) = 989.5 ft
Similarly, with the PVI at elevation 989.5 ft, the elevation of the PVT is
Since the curve is equal tangent, the PVI will be 300 ft or three stations (measured in a
horizontal plane) from the PVC, and the PVT will be 600 ft or six stations from the PVC.
Therefore, the stationing of the PVI and PVT is 173 +00 and 176 +00, respectively. For the
elevations of the PVI and PVT, it known that a -3.5% grade can be equivalently written
as -3.5 ft/station (a 3.5 ft drop per 100 ft of horizontal distance). Since the PVI is three
stations from the PVC, which is known to be at elevation 1000 ft, the elevation of the PVI is
Geometric Design of Highways
7,280
989.5 +0.5 ft/station X (3 stations) = 991.0 ft
It is clear from the values of the initial and final grades that the lowest point on the vertical
curve will occur when the first derivative of the parabolic function (Eq. 3.1) is zero because
the initial and final grades are opposite in sign. When initial and final grades are not
opposite in sign, the low (or high) point on the curve will not be where the first derivative is
zero because the slope along the curve will never be zero. For example, a sag curve with an
initial grade of -2.0% and a final grade of -2.0% will have its lowest elevation at the PVT,
and the first derivative of Eq. 3.1 will not be zero at any point along the curve. However, in
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Transcribed Image Text:Messages File Edit View Conversations Window Help Transportation engineering textbook.pdf EXAMPLE 3.1 SOLUTION Chapter 3 VERTICAL CURVE STATIONS AND ELEVATIONS A 600-ft equal-tangent sag vertical curve has the PVC at station 170+ 00 and elevation 1000 ft. The initial grade is -3.5% and the final grade is +0.5%. Determine the stationing and elevation of the PVI, the PVT, and the lowest point on the curve. 1000-3.5 ft/station X (3 stations) = 989.5 ft Similarly, with the PVI at elevation 989.5 ft, the elevation of the PVT is Since the curve is equal tangent, the PVI will be 300 ft or three stations (measured in a horizontal plane) from the PVC, and the PVT will be 600 ft or six stations from the PVC. Therefore, the stationing of the PVI and PVT is 173 +00 and 176 +00, respectively. For the elevations of the PVI and PVT, it known that a -3.5% grade can be equivalently written as -3.5 ft/station (a 3.5 ft drop per 100 ft of horizontal distance). Since the PVI is three stations from the PVC, which is known to be at elevation 1000 ft, the elevation of the PVI is Geometric Design of Highways 7,280 989.5 +0.5 ft/station X (3 stations) = 991.0 ft It is clear from the values of the initial and final grades that the lowest point on the vertical curve will occur when the first derivative of the parabolic function (Eq. 3.1) is zero because the initial and final grades are opposite in sign. When initial and final grades are not opposite in sign, the low (or high) point on the curve will not be where the first derivative is zero because the slope along the curve will never be zero. For example, a sag curve with an initial grade of -2.0% and a final grade of -2.0% will have its lowest elevation at the PVT, and the first derivative of Eq. 3.1 will not be zero at any point along the curve. However, in A iMessage 25 Open w tv S MacBook Pro
a 600 ft equal tangent sag vertical curve has the PVC at Station 170+00 and elevation
1000 ft. The initial grade is -3.5% and the final grade is +0.5%. Determine the stationing
And elevation of the PVI, the PVT, and the lowest point on the curve.
L=600 ft
T=300 ft
Options
-3.5%
PVC = PVT-L
17000 = PVT -600
17600 = PVT
176 +00= PVT
PVC
170+00
PUI = PVC + T
54°F
Cloudy
Elevation
1000
= 17,000 + 300
- 17300
PVI = 173+00
-
y = 2ax + b
O Search
PVI
173+00
Elevation =
a
989.5'
Elevation PUI = E pvc + 9²/12
= 1000 + (-0.035) (600)
=
989.5'
G₂+0.5%
PVT
1776+00
elevation = 974.5¹
Elevation PVT = EPI-9²/2/2
b=
= 989.5 - (+0.05)(b)
= 974.5'
a=
= G₂-G₁₂₁ = 0.05-(-0.035)
2L
2(600)
= 7.0833•10-5
0.035
4:54 PM
Transcribed Image Text:a 600 ft equal tangent sag vertical curve has the PVC at Station 170+00 and elevation 1000 ft. The initial grade is -3.5% and the final grade is +0.5%. Determine the stationing And elevation of the PVI, the PVT, and the lowest point on the curve. L=600 ft T=300 ft Options -3.5% PVC = PVT-L 17000 = PVT -600 17600 = PVT 176 +00= PVT PVC 170+00 PUI = PVC + T 54°F Cloudy Elevation 1000 = 17,000 + 300 - 17300 PVI = 173+00 - y = 2ax + b O Search PVI 173+00 Elevation = a 989.5' Elevation PUI = E pvc + 9²/12 = 1000 + (-0.035) (600) = 989.5' G₂+0.5% PVT 1776+00 elevation = 974.5¹ Elevation PVT = EPI-9²/2/2 b= = 989.5 - (+0.05)(b) = 974.5' a= = G₂-G₁₂₁ = 0.05-(-0.035) 2L 2(600) = 7.0833•10-5 0.035 4:54 PM
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