Guild of Project Controls: Compendium | Roles | Assessment | Certifications | Membership

Tips on using this forum..

(1) Explain your problem, don't simply post "This isn't working". What were you doing when you faced the problem? What have you tried to resolve - did you look for a solution using "Search" ? Has it happened just once or several times?

(2) It's also good to get feedback when a solution is found, return to the original post to explain how it was resolved so that more people can also use the results.

How to propotionate Man power / trade

6 replies [Last post]
Saju TS
User offline. Last seen 8 years 27 weeks ago. Offline
Joined: 24 Jun 2009
Posts: 22

How to proportionate  manpower per trade?

For example for an RCC work, I have duration, RCC productivity of compnay per day ( manday) and total quanity of RCC

First i divdied the Total quanityof RCC by duration  for getting RCC work per day. then i divied this by company productivity/ mandays. I got total number of man days / day. Now how to proportionate  this man days as steel fixer,carpenter,helper,mason  from the total man hours per day

Replies

siddeeq akbar
User offline. Last seen 11 years 39 weeks ago. Offline
Joined: 16 May 2012
Posts: 2

hi

how can i update,

for eg:in my program having six zone

for electricai duct

total no is 1212

setting out&formation(25%)-300 completeted

shuttering and concreting(65%)-274 completed

backfilling(10%)-20 is completed

with regards

siddeeq akbar

Rafael Davila
User offline. Last seen 10 hours 3 min ago. Offline
Joined: 1 Mar 2004
Posts: 5229

Resource leveling breaks the CPM relationships?

No it is just the traditional CPM calculations will not keep the activities together.

Just model the sample job using any software and you will find out the activities you expect to occur in parallel might not occur as expected, it is enough for at any given time the lack of resources delays the incidental activity using FS and FF links, not to say if using a single link. If this happens then the predecessor should be delayed as to occur in parallel but this is not how CPM model works. 

The following figure will give you the data for availability and assignment of resources plus the logic required to make the model using your software.

Photobucket

Note there are 2 form slab crews while there is only one reinforcing steel crew.

Using Spider Project you can model the schedule using separate activities in combination with strict links as follows and will yield expected results on this simple schedule. I doubt MSP or any Primavera product has such functionality but it wold be interesting to run the test. 

Photobucket

Still I am reluctant to use strict links because they apply to resource leveling only and it might be that at some point some non driving logic link becomes driving a condition that might break the "strict" link delaying the successor but not keeping the predecessor in parallel. I play it safe and keep the crews assigned to a single activity and use the strict links functionality with much care only when assigning the different crews to the same activity is not feasible.. 

It is true you can work it out correctly but single activity is safer. In addition if you transfer the model to other software lacking strict links functionality it might spell disaster. Another issue is that strict links are limited to a single outgoing link per activity and in the case you need to model more than two related crews it will not make it. This can be solved bu linking SS related activities in tandem instead of one to many but can be error prone if not done with care.

Photobucket

Mike Testro
User offline. Last seen 5 weeks 3 days ago. Offline
Joined: 14 Dec 2005
Posts: 4418

Hi Bernard

All of them that applies resource levelling correctly.

Thatis why I never use it.

Best regards

Mike Testro

Bernard Ertl
User offline. Last seen 9 years 19 weeks ago. Offline
Joined: 20 Nov 2002
Posts: 757

"It is simple, if you keep the incidental works under separate tasks they might not be scheduled by the resource leveling to happen on parallel even if using SS and FF relationships."

Resource leveling breaks the CPM relationships?  What software does this?

Rafael Davila
User offline. Last seen 10 hours 3 min ago. Offline
Joined: 1 Mar 2004
Posts: 5229

I do not agree with the following statement with regard to the splitting each section into separate tasks for rebar and formwork. 

"You must split the RCC tasks into sections such as Slabs - Columns - Walls - shafts then break each section down into separate tasks for Rebar forms and pouring."

It is in error to require different crews that must work at the same time on an activity [all the time or part of the time] to be loaded under separate activities. It is simple, if you keep the incidental works under separate tasks they might not be scheduled by the resource leveling to happen on parallel even if using SS and FF relationships. The same goes for shift work. The following figure shows a resource assignment that is an easy option to meet this need. 

Photobucket

I have seen very poor specifications that requires you to keep the crews on different activities simply because the specified software lacks good resource loading functionality. The following figure illustrates how bad this practice can be. At times it will work as intended such as for Slab A but at times it might not such as for Slab B. As your job progress this can get worse, it might happens no single pair of activities happen in parallel.

Photobucket

I agree resource loading on concrete pouring requires a separate activity.

Mike Testro
User offline. Last seen 5 weeks 3 days ago. Offline
Joined: 14 Dec 2005
Posts: 4418

Hi Saju

The short answer is that you can't do it with any degree of accuracy.

You must split the RCC tasks into sections such as Slabs - Columns - Walls - shafts then break each section down into seperate tasks for Rebar forms and pouring.

Then you can allocate the different resouces into the respective tasks.

This is called bottom up planning and is the most accurate and responsive form of planning that there is.

Best regards

Mike Testro