Production/Cycle Time Problem

[sgsmith2_PE]

A job requires gravel fill to be hauled from a stockpile to the jobsite. Given the information in the table, what is the installed cost per cubic yard of the gravel fill?

quantity required 15,000 yd3

stockpile distance from job site 30 mi

average truck speed 25 mph

truck capacity 45,000 lbm

gravel compacted density 148 lbm/ft3

truck load time 15 min

truck unload time 15 min

gravel cost at stockpile $3 per ton

truck cost per hour, including driver $75

cost to place and compact gravel $0.50 per yd3

A. $1.5/yd3

B. $18/yd3

C. $23/yd3

D. $26/yd3

 

[mrt406]

I'm sure I made some sort of mistake along the way... but I worked out:

$289,710 for the truck costs

$89,910 for the gravel itself

$7,500 for the place and compaction

Which works out to $25.81 per CY...

So my answer would be (D.)!

 

[yatkins]

You forgot a few factors

Teamster/Union "break" time: 20 min/hr

Truck broken down or lost: 1 hr/day

Driver brings load of sand instead of gravel: 1 load/day

 

[humner]

Wait a minute, your teamster/union break time is 20 min/hr? we only get 15 min/hr. They owe us 5 min/hr. I guess I can retire now with all that lost break time. LOL

 

[sgsmith2_PE]

The answer is D. Good work MRT. I got it the first time but it has a bunch of things going on so I figured it would be a good problem. My guess is that it's probably something equivalent to the difficulty we'd see in the afternoon. Only thing with this problem is that they give you compacted unit weight so you have to use that for hauling. I guess stone doesn't really differ that much between compacted and loose.

 

[sgsmith2_PE]

The answer is D. Good work MRT. I got it the first time but it has a bunch of things going on so I figured it would be a good problem. My guess it's that probably something equivalent to the difficulty we'd see in the afternoon. Only thing with this problem is that they give you compacted unit weight so you have to use that for hauling. I guess stone doesn't really differ that much between compacted and loose.

 

[ElCid03]

I you can handle this example, then you should not worry about Friday.