Ncees pe hb 1.1, p. 367, 388. Love this problem. But got a tad different answer so I think the presenter rounded too soon: S_x = 0.0256 = 2.567 % = 2.6% But this answer isn't listed so by engineering judgement I'm tempted to round up to 3%, which isn't correct, according to the problem setup. So I think the solutions list needs to be amended to include 2.6% OR require the engineer to round up to 3% using "engineering judgement". Also...the real PE exam ALWAYS lists answers in an increasing order. Your answers are scattered in value. Why ? Thanks.
Ncees pe hb 1.1, p. 367, 388. Manning n is responsible for the roughness. Think of roughness as on a scale of very rough to very smooth. Roadways are made of concrete, asphalt, and compacted dirt. The former 2 are relatively smooth when compared to other surfaces such as grass, rubble, etc. Your thought process should look like a list: . What's my road material? Asphalt or concrete. . Which n does concrete and asphalt have? . I'll take an average of the range reported in the n-chart. N= 0.0115 . Plug n into gutter equation. . Solve problem for S_x. . Done.
Valley gutters are almost always made of concrete, which has a Manning's roughness coefficient of 0.011. I understand if you solved with a coefficient of 0.013 for asphalt your answer should have been 2.76, so the question definitely should have clarified material type in the gutter area.
No. Read problem statement carefully. It's easy to misinterpret. Also, dividing Q for a gutter problem is highly unusual for this type of problem. I've done a bunch like this. There is never even a hint of dividing by 2. The Q is intimately connected to that just 1 side of street.
Ncees pe hb 1.1, p. 367, 388.
Love this problem. But got a tad different answer so I think the presenter rounded too soon:
S_x = 0.0256 = 2.567 % = 2.6%
But this answer isn't listed so by engineering judgement I'm tempted to round up to 3%, which isn't correct, according to the problem setup.
So I think the solutions list needs to be amended to include 2.6% OR require the engineer to round up to 3% using "engineering judgement".
Also...the real PE exam ALWAYS lists answers in an increasing order. Your answers are scattered in value. Why ?
Thanks.
Manning n for asphalt is 0.013? Why would we use cement to find the cross slope of the road?
Ncees pe hb 1.1, p. 367, 388.
Manning n is responsible for the roughness. Think of roughness as on a scale of very rough to very smooth.
Roadways are made of concrete, asphalt, and compacted dirt. The former 2 are relatively smooth when compared to other surfaces such as grass, rubble, etc.
Your thought process should look like a list:
. What's my road material? Asphalt or concrete.
. Which n does concrete and asphalt have?
. I'll take an average of the range reported in the n-chart. N= 0.0115
. Plug n into gutter equation.
. Solve problem for S_x.
. Done.
Valley gutters are almost always made of concrete, which has a Manning's roughness coefficient of 0.011. I understand if you solved with a coefficient of 0.013 for asphalt your answer should have been 2.76, so the question definitely should have clarified material type in the gutter area.
Dont we need to divide 3.36cfs by 2 ?
I think you are right since the problem says the gutter slope is the same as the cross slope.
I felt that this we were calculating the flow generated from one of the two gutter lines, keeping the 10' lane in the center. I agree with you here.
No. Read problem statement carefully. It's easy to misinterpret. Also, dividing Q for a gutter problem is highly unusual for this type of problem. I've done a bunch like this. There is never even a hint of dividing by 2.
The Q is intimately connected to that just 1 side of street.
problem statement doesn't make it clear, whether the 3.36 cfs is per gutter or for both gutters combined. hopefully exam questions will make it clear.
What is PE 367 in reference to? This equation doesn't show up in the CERM?
The PE Reference Handbook from the NCEES. Go get a free copy in your account.
Ncees pe hb 1.1, p. 367, 388.
Cerm is dead.
problem statement text is small. i have to open video on a large screen just to make out the wording. please increase font.