an existing highway-railway at-grade crossing is being redesigned as grade separated to improve traffic operations. The railway
must remain at the same elevation. The highway is being reconstructed to travel under the railway. The underpass will be a sag curve that has an initial grade of -2% and a final grade of 2%. The PVI of the sag curve will be centered under the railway (a symmetrical alignment). The sag curve design speed is 45 mi/h. How many feet below the railway should the curve PVI be located
1 answer:
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Answer:
6.5 × 10¹⁵/ cm³
Explanation:
Thinking process:
The relation
With the expression Ef - Ei = 0.36 × 1.6 × 10⁻¹⁹
and ni = 1.5 × 10¹⁰
Temperature, T = 300 K
K = 1.38 × 10⁻²³
This generates N₀ = 1.654 × 10¹⁶ per cube
Now, there are 10¹⁶ per cubic centimeter
Hence,