In this solution, may I know where they got the 0.01 slope?
Chapter2: Loads On Structures
Section: Chapter Questions
Problem 1P
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Question
In this solution, may I know where they got the 0.01 slope?
Transcribed Image Text:Connects A +2.5% And A -1.5% Grade. If The Design Speed Of The...
Example 4
A crest vertical curve is 1200 m long and connects a +2.5% and a -1.5% grade. If the design
speed of the roadway is 90 km/h, does this curve have adequate passing sight distance?
![Solution:
Length of vertical curve (L) = 1200 m
1st Gradient (1₁) = 2.5%
2nd Gradient (1₂) 2-1.5%
velocity of vehicle (U) = 90km/h
= 25 m/sec
Now let assume
Length of curve (2) > Safe sight distance (5)
L = NS²
2 (55+5)
Here N = (n₁-n₂) = [2·5-(-1·5)] = 4°%
hi ->
driver's
eye
Height of the object above the pavement
sterface"
= 0.15 m
〃
h₂ →
Height of
1.2m
L = NS²
4.4
above road surface
1200 = 0.045²
4.4
=)
Spro= 363.30 m
Here we can see that L>S Hence
our assumption is correct.
Now
Miss Safe Distance required on road is
Smin = vt + v²
29 (+-0.0142)
driver
t→ Reaction time
of
= d.5 sec. (Assumed)](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F224ff15e-cbd7-45f2-bb2d-fe7f4381a66a%2F9c232d44-d26c-463f-9edc-5b17857aa9f8%2Fiakx5ov_processed.png&w=3840&q=75)
Transcribed Image Text:Solution:
Length of vertical curve (L) = 1200 m
1st Gradient (1₁) = 2.5%
2nd Gradient (1₂) 2-1.5%
velocity of vehicle (U) = 90km/h
= 25 m/sec
Now let assume
Length of curve (2) > Safe sight distance (5)
L = NS²
2 (55+5)
Here N = (n₁-n₂) = [2·5-(-1·5)] = 4°%
hi ->
driver's
eye
Height of the object above the pavement
sterface"
= 0.15 m
〃
h₂ →
Height of
1.2m
L = NS²
4.4
above road surface
1200 = 0.045²
4.4
=)
Spro= 363.30 m
Here we can see that L>S Hence
our assumption is correct.
Now
Miss Safe Distance required on road is
Smin = vt + v²
29 (+-0.0142)
driver
t→ Reaction time
of
= d.5 sec. (Assumed)
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