overhaul vs free haul distance

[ketanco]

in the attachment i downloaded from learncivilengineering.com site for the earthwork mass diagrams, in problem #4, it says overaul volume equals freehaul volume. why is that?

 

[ptatohed]

Attachment?

 

[JMT]

[SIZE=10pt][/SIZE]

[SIZE=10pt][/SIZE]

 

[JMT]

http://postimg.org/image/b72jzovt3/

http://postimg.org/image/opco3bnkj/

 

[ptatohed]

Thanks JM.

Okay, this is how I did it (before looking at the answer).

The total distance the dirt needs to be hauled is from 9+63 to 15+21. 1521 - 963 = 558 total feet

The freehaul (the maximum distance in which the contractor is required to move the dirt before he can charge additional money) is 1456 - 1039 = 417 feet

So, the overhaul (the distance beyond the freehaul) must be 558' - 417' = 141 feet

If the overhaul distance of 141' results in 642,186 CY-ft, then what does the freehaul distance of 417' result in? Using ratio: 141/642,186 = 417 / x, x = 1,899,230.9 CY-ft

Divide by the freehaul footage and you get 1,899,230.9 CY-ft / 417 ft = 4554.5 CY

 

[ketanco]

Thanks JM.

Okay, this is how I did it (before looking at the answer).

The total distance the dirt needs to be hauled is from 9+63 to 15+21. 1521 - 963 = 558 total feet

The freehaul (the maximum distance in which the contractor is required to move the dirt before he can charge additional money) is 1456 - 1039 = 417 feet

So, the overhaul (the distance beyond the freehaul) must be 558' - 417' = 141 feet

If the overhaul distance of 141' results in 642,186 CY-ft, then what does the freehaul distance of 417' result in? Using ratio: 141/642,186 = 417 / x, x = 1,899,230.9 CY-ft

Divide by the freehaul footage and you get 1,899,230.9 CY-ft / 417 ft = 4554.5 CY

i understand how we obtained overhaul distance. but then, how can you make that logic proportioning? i dont understand the logic here. with the same logic, in the attachment it said freehaul volume = overhaul volume.. why?

 

[ptatohed]

I think the trick is in the question. Volume is volume. They ask for the 'Freehaul Volume' but really they are asking for the volume. Period. Freehaul, Overhaul and Total Haul are distances, not volumes. They could have just as well asked for the Total Haul volume and the answer would be the same.

ketanco drove 3 friends in his 2008 Toyota Carolla 100 miles on the first leg of the road trip. How many friends did ketanco drive if he drove 150 miles on the second leg of the road trip? The answer is still 3. Does that make sense?

 

[ptatohed]

So, can anyone confirm that I am not all washed up?