Introduction to Transportation Engineering Alignment Design Vertical Alignment
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Introduction to Transportation Engineering Alignment Design Vertical Alignment Instructor Dr. Norman Garrick Hamed Ahangari May 2014
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Introduction to Transportation Engineering Alignment Design Vertical Alignment. Instructor Dr. Norman Garrick Hamed Ahangari May 2014. Basic Elements. Horizontal Alignment Vertical Design Cross Section. Horizontal Alignment. Vertical Alignment. Crest Curve. G 2. G 3. G 1. - PowerPoint PPT Presentation
Transcript of Introduction to Transportation Engineering Alignment Design Vertical Alignment
Introduction to Transportation EngineeringAlignment DesignVertical Alignment
Instructor Dr. Norman Garrick
Hamed AhangariMay 2014
Basic Elements
• Horizontal Alignment
• Vertical Design
• Cross Section
3
Horizontal Alignment
Vertical Alignment
Crest Curve
Sag Curve
G1
G2 G3
Design of Vertical Curves
5
Parabolic CurveBVC
EVC
L
G2
G1
L/2L/2
PI
Change in grade: A = G2 - G1 G is expressed as %
Rate of change of curvature: K = L / |A|
Rate of change of grade: r = (g2 - g1) / L
Equation for determining the elevation at any point on the curvey = y0 + g1x + 1/2 rx2
where,y0 = elevation at the BVC g = grade expressed as a ratio
x = horizontal distance from BVC r = rate of change of grade (ratio)
A
B
El. 100
`
140
120
130
110
150
170
180
190
160
El. 200
Alignment Standard related to Design Speed
Design Speed(mph)
Minimum Radius of Horizontal Curve
(ft)
Maximum Percentage of Grade
Minimum Length of Vertical Curve for
each 1% of Algebraic Differences
20 100 12 10
30 250 10 20
40 450 8 35
50 750 7 70
60 1100 5 150
70 1600 4 200
Site Engineering by Steven Storm
` A
BEl. 200
El. 100
140
120
130
110
170
160
150
180
190
` A
BEl. 200
120
150
180
130
170
110
140
160
190
0+00
1+00
2+00
3+00
4+00
5+00
6+00
7+00
8+00
9+00
10+00
11+50
11+00
Longitude Profile
Distance
Elevation
100
200
300
400
500
600
700
800
900
1000
1100
100
120
140
160
180
200B (1150,200)
A (0,100)
Distance
100
200
300
400
500
600
700
800
900
1000
1100
100
120
140
160
180
200B (1150,200)
A (0,100)
Elevation
G1=10%h=40’,d=400’
h=20’,d=320’G2=6.25%
h=40’,d=430’G3=9.3%
Distance
100
200
300
400
500
600
700
800
900
1000
1100
100
120
140
160
180
200B (1150,200)
A (0,100)
Elevation
G1=10%
G2=6.25%
G3=9.3%
Vertical alignment
• Step 1: First provide the longitude profile of the road which contain earth elevations.
• Step 2: Based on the maximum allowable slope and topographic condition, determine vertical tangents.
• Step 3: Calculate the parabolic vertical curve specifications.
Example
We want to design a road which connect point A and B
• Design Speed is 30 mph
• Provide vertical alignment for this road
`
A
B
