Difficult Vertical Curve problem

[winner9459]

If any one can solve this problem, it would be really nice and much appreciated.

 

[lady_j]

winner - I'm going to tackle this one later when I have my books around

 

[ckjy]

Q-13:Let x be the station of PI: Eleveation of PI can be expressed by 2 expressions which we can make an equation to solve for x:

240.6-2.5(x-20.10)=243.30-1.5(30.30-x)--> solve for x=23.25 so station of PI is 23+25

Answer is B

Q-14: Substitute x into either side of the equation above to solve for elevation of PI: 240.6-2.5(23.25-20.10)=232.72

Answer is C

Q-15:L=1300--> R=(G2-G1)/L=(1.5+2.5)/(13)=0.30769; G1=-2.5

Vertical Curve equation: (R/2)x2+G1x+yBVC

Find yBVC: yBVC= yPI-G1*L/2=232.72+2.5*6.5=248.97

Equation then will be: 0.154x2-2.5x+248.97

xBVC= xPI-L/2=23.25-13/2=16.75

At station 28+00 x= 28-16.75=11.25

Substitute 11.25 to the vertical curve euqtion to get y=240.33. Add the minimum clrearance requirement of 30ft ---> require elevetion of the vertical obstacle is 270.34. The power line is located at elevation 272ft which is higher than the minimum requirement--> the curve satiffy the design requirement

Answer is A

Q-16: x at low point is -G1/R=8.125--> station of lowpoint is xBVC+8.125=16.75+8.125=24.875---> 24+87.5

Answer is D

Q-17: Substitute 8.125 to the vertical curve equation to get the eleveation.

Answer is B

Hope that help!! Good luck on the exam. 10940623:

 

[winner9459]

Thank you. You made it look real simple.

 

[structuraleit]

If any one can solve this problem, it would be really nice and much appreciated.

This looks like a scan from PES