ktulu
Well-known member
I don't know how many of us are working the 439 practice problems that are the companion to the CERM, but the solutions that they use are, in a few cases, way too in depth to find the answer.
I found this example this morning:
For example, problem #2 in Section 79 (highway curves): the problem asks to find the required length of curve that is required to be at least 15 ft. under an overpass. The solution uses proportional ratios to find the answer. I understand how they did it.
But, a simpler way to find the answer uses only (2) equations found in the CERM: Eqns 79.46 & 79.47
1.) Find the elevation directly under the overpass, remembering that is has to be 15 ft. below the overpass,
134.06 ft (elev. overpass) - 15 ft = 110.06 ft.
2.) Use Eqn 79.47 to find R -- R = 1.11%/sta
3.) Use Eqn 79.46 to find L -- L = 8.1 sta
I just thought it was a lot easier than using proportions based on the BVC....
:beerchug:
On another note: does anyone agree that ALOT of these questions are geared for the DEPTH section of the exam? Based on general solutions they give? Just curious....
I found this example this morning:
For example, problem #2 in Section 79 (highway curves): the problem asks to find the required length of curve that is required to be at least 15 ft. under an overpass. The solution uses proportional ratios to find the answer. I understand how they did it.
But, a simpler way to find the answer uses only (2) equations found in the CERM: Eqns 79.46 & 79.47
1.) Find the elevation directly under the overpass, remembering that is has to be 15 ft. below the overpass,
134.06 ft (elev. overpass) - 15 ft = 110.06 ft.
2.) Use Eqn 79.47 to find R -- R = 1.11%/sta
3.) Use Eqn 79.46 to find L -- L = 8.1 sta
I just thought it was a lot easier than using proportions based on the BVC....
:beerchug:
On another note: does anyone agree that ALOT of these questions are geared for the DEPTH section of the exam? Based on general solutions they give? Just curious....