Resource levelling

[Sam Construction]

Someone was asking about a resource levelling problem. Here is a resource leveling problem

260 foot long concrete wall, 10 foot height has been getting poured in 30 feet increments using the following schedule.

Set forms 2 days with 3 carpenters

Pour concrete 1 day, 4 laborers, 3 carpenters and 1 concrete finisher

Strip forms 1 day with 4 carpenters, 1 concrete finisher

The contractor would like to know approximately how much many days will be lost, if he utilizes only 3 carpenters for this operation, given that 120 feet is already completed.

a. 4 Days

b. 2.5 Days

c. 1.5 Days

d. 3 Days

Solution:

Current production

30 feet of wall in (2 days+1 day + 1 day = 4 days)

New production using only 3 carpenters

If 4 carpenters strip 30 feet of wall in 1 day, then 3 carpenters will strip 22.5 feet in 1 day, and they will use .3 of the following day to complete stripping.

30 feet of wall in ( 2 days+1day+1.3 days= 4.3 days)

Remaining work is 260 feet-120 = 140 feet .

140/30 = 4 increments + .667 of an increment or 20 feet.

Time lost for the 4 remaining increments = 4*.33 das = 1.32

The lost time in the remaining 20 feet is .667 * .33 = .22

Total lost time 1.54

Correct answer is C

They can also ask for total duration to build the wall which would be,, you guys can get the point. Right.

 

[maryannette]

Interesting problem, but I can almost guarantee that there will not be a scheduling problem that complicated on the exam.

My PE exam did have 2 problems about critical path, but it was more like connect the dots and do some deductive reasoning.

 

[RIP - VTEnviro]

What is critical path? Is that a scheduling term?

 

[Sam Construction]

Mary, Did you take the construction PM?

You have got problems if you don't know what is CPM schedule..? Critical Path Method Schedule. google it..

 

[maryannette]

Mary, Did you take the construction PM?
You have got problems if you don't know what is CPM schedule..? Critical Path Method Schedule. google it..

No, I didn't take Constr PE. I took Civil, Transportation depth. I didn't mean any offense or to mislead anyone. I guess I was off base about the complexity of scheduling/resource levelling problems to expect.

Yes, critical path is a scheduling term. It refers to the schedule that would be the most compressed with tasks beginning as soon as the "predecessor task" is complete.

 

[Venpr]

Mary, Did you take the construction PM?
You have got problems if you don't know what is CPM schedule..? Critical Path Method Schedule. google it..

I need to know in theNCEES Sample and Solutions, Problem 502

how they get the intersection angle = 41.22 degres

12.8ft=200ft(1- cos I/2)

I=? They use a trig identiti o I am a Gigantic DoucheBag

 

[tymr]

I'm not sure what step gave you problems, but here's a solution for you.

Given:

M = 12.8 ft

R = 200 ft

then,

M = R(1-cos(I/2))

12.8 = 200(1-cos(I/2))

0.0640 = 1-cos(I/2)

-0.936 = -cos(I/2)

therefore,

0.936 = cos(I/2)

arc cos 0.936 = I/2

20.61 = I/2

I = 41.22 (degrees)

Hope that helps. Let me know if you still have questions.

 

[Venpr]

I'm not sure what step gave you problems, but here's a solution for you.
Given:

M = 12.8 ft

R = 200 ft

then,

M = R(1-cos(I/2))

12.8 = 200(1-cos(I/2))

0.0640 = 1-cos(I/2)

-0.936 = -cos(I/2)

therefore,

0.936 = cos(I/2)

arc cos 0.936 = I/2

20.61 = I/2

I = 41.22 (degrees)

Hope that helps. Let me know if you still have questions.

 

[Venpr]

I"m sure I will!!!!

But for now thanks, because I don't know what Iwas thinking

 

[Wendy]

Someone was asking about a resource levelling problem. Here is a resource leveling problem
260 foot long concrete wall, 10 foot height has been getting poured in 30 feet increments using the following schedule.

Set forms 2 days with 3 carpenters

Pour concrete 1 day, 4 laborers, 3 carpenters and 1 concrete finisher

Strip forms 1 day with 4 carpenters, 1 concrete finisher

The contractor would like to know approximately how much many days will be lost, if he utilizes only 3 carpenters for this operation, given that 120 feet is already completed.

a. 4 Days

b. 2.5 Days

c. 1.5 Days

d. 3 Days

Solution:

Current production

30 feet of wall in (2 days+1 day + 1 day = 4 days)

New production using only 3 carpenters

If 4 carpenters strip 30 feet of wall in 1 day, then 3 carpenters will strip 22.5 feet in 1 day, and they will use .3 of the following day to complete stripping.

30 feet of wall in ( 2 days+1day+1.3 days= 4.3 days)

Remaining work is 260 feet-120 = 140 feet .

140/30 = 4 increments + .667 of an increment or 20 feet.

Time lost for the 4 remaining increments = 4*.33 das = 1.32

The lost time in the remaining 20 feet is .667 * .33 = .22

Total lost time 1.54

Correct answer is C

They can also ask for total duration to build the wall which would be,, you guys can get the point. Right.

How to do the total duration?

 

[YJ_Civil_PE]

Let's see if I got this right:

(Total duration to build the wall) = (260' long wall) x (4 days)/(30 ft) = 34.7 ---> 35 days with current crew members.

After completion of 120', 3 carpenters instead of 4, 3 carpenters will strip 22.5 feet in a day.

(New production rate) = (2 days to set form) + (1 day to pour conc.) + (1 day to strip form) = 4 days to build 22.5 feet.

(Total duration to build the wall) = (120' long wall) x (4 days)/(30 ft) + (140' long wall) x (4 days)/(22.5 ft) = 40.9 ---> 41 days with reduced crew members after completion of 120'.

 

[peprep]

Let's see if I got this right:
(Total duration to build the wall) = (260' long wall) x (4 days)/(30 ft) = 34.7 ---> 35 days with current crew members.

After completion of 120', 3 carpenters instead of 4, 3 carpenters will strip 22.5 feet in a day.

(New production rate) = (2 days to set form) + (1 day to pour conc.) + (1 day to strip form) = 4 days to build 22.5 feet.

(Total duration to build the wall) = (120' long wall) x (4 days)/(30 ft) + (140' long wall) x (4 days)/(22.5 ft) = 40.9 ---> 41 days with reduced crew members after completion of 120'.

If Total duration to build the wall with 4 carpenters = 35 days,

and as per the resource levelling the total delay will be 1.54 days to build the 140' wall, then should it not be 35 days + 1.54 days = 36.2 days?

 

[PE_2009]

Let's see if I got this right:
(Total duration to build the wall) = (260' long wall) x (4 days)/(30 ft) = 34.7 ---> 35 days with current crew members.

After completion of 120', 3 carpenters instead of 4, 3 carpenters will strip 22.5 feet in a day.

(New production rate) = (2 days to set form) + (1 day to pour conc.) + (1 day to strip form) = 4 days to build 22.5 feet.

(Total duration to build the wall) = (120' long wall) x (4 days)/(30 ft) + (140' long wall) x (4 days)/(22.5 ft) = 40.9 ---> 41 days with reduced crew members after completion of 120'.

If Total duration to build the wall with 4 carpenters = 35 days,

and as per the resource levelling the total delay will be 1.54 days to build the 140' wall, then should it not be 35 days + 1.54 days = 36.2 days?

I think that 1.54 man days are lost. 1.54 times 4 man days = 6.16 days. So new duration will be 35 + 6.16 = 41.16 days

 

[Samuel]

Someone was asking about a resource levelling problem. Here is a resource leveling problem
260 foot long concrete wall, 10 foot height has been getting poured in 30 feet increments using the following schedule.

Set forms 2 days with 3 carpenters

Pour concrete 1 day, 4 laborers, 3 carpenters and 1 concrete finisher

Strip forms 1 day with 4 carpenters, 1 concrete finisher

The contractor would like to know approximately how much many days will be lost, if he utilizes only 3 carpenters for this operation, given that 120 feet is already completed.

a. 4 Days

b. 2.5 Days

c. 1.5 Days

d. 3 Days

Solution:

Current production

30 feet of wall in (2 days+1 day + 1 day = 4 days)

New production using only 3 carpenters

If 4 carpenters strip 30 feet of wall in 1 day, then 3 carpenters will strip 22.5 feet in 1 day, and they will use .3 of the following day to complete stripping.

30 feet of wall in ( 2 days+1day+1.3 days= 4.3 days)

Remaining work is 260 feet-120 = 140 feet .

140/30 = 4 increments + .667 of an increment or 20 feet.

Time lost for the 4 remaining increments = 4*.33 das = 1.32

The lost time in the remaining 20 feet is .667 * .33 = .22

Total lost time 1.54

Correct answer is C

They can also ask for total duration to build the wall which would be,, you guys can get the point. Right.

A more direct approach:

260 -120 = 140 ft (Remaining length)

At 30ft pour, =140/30 = 4.67 days (with 4 carpenters)

Now using 3 carpenters, we have 4/3 x 4.67 = 6.21 days

The extention will be 6.21 - 4.67 = 1.54

The answer ic C