Identify the work break-down structure (WBS) for the overall Preliminaries
List of assumptions: (mymanagementguide, 2010), (Learningtree, 2012), (Pmstudycircle, 2017), (Toolbox, 2017) & (Simplicable, 2015)
The list of assumptions considered during the development of the Construction Schedule of G+2 residential building having mainly 27 rooms, 3 studio rooms, retail space, recreation room, kitchen, laundry, car parking at ground level, overhead water tank etc. are as below:
Raw materials required are readily available at construction site as per requirement
Potable water shall be provided by water tanker
Delay because of local / financial / permission issues are not considered, whereas cushions are there in duration estimation
Foundation work has one lift of column casting for the plinth beam
Pipeline work for sanitary system to be done after the completion of work for the first floor
Backfilling to be done for the building area just after the casting of Plinth Beam
Plastering work shall be performed only after the completion of all kinds of conduit work
Props / support of Slab & Beams cannot be removed before 21 days of proper curing
No constraints for supply of formwork
‘MS’ stands for Milestone
As the number of floors we go up, the duration of work required increases due to decrease in efficiency of worker and difficulties in arranging supports require more man-hours
Saturday & Sunday considered as off day, 5 working days a week
Working hours of 08:00 to 17:00, including lunch break of 1hrs.
Work Breakdown Structure: (Stakeholdermap, 2017), (Slideshare, 2009), (Workbreakdownstructure, 2017), (sdc.wsu.edu, 2017) & (Bnl, 2003)
Sequence and dependencies: (Management, 2017) & (Thebalance (2016)
There are totally four types of relationships that we can use to provide sequencing of the activities. These four types are SS (Start to Start), FS (Finish to Start), FF (Finish to Finish) and very rarely used SF (Start to Finish).
Let us first see the relationship we used to develop the construction schedule:
|
WBS |
Task Name |
Duration |
Predecessors |
Successors |
|
1 |
Construction of G+2 storied Building |
368 days |
||
|
1.1 |
Sub-Contract job |
15 days |
||
|
1.1.1 |
MS-1. Finalization of Contract with Developer |
0 days |
4,6FS+10 days,8FS+10 days,10FS+10 days,12FS+10 days,14FS+10 days |
|
|
1.1.2 |
Mobilization of Workers and Machineries at site |
15 days |
3 |
18 |
|
1.2 |
Procurement / Local Purchase |
5 days |
||
|
1.2.1 |
MS-2. Placement of Purchase Order of Cement at site |
0 days |
3FS+10 days |
7 |
|
1.2.2 |
Delivery of Cement at site |
5 days |
6 |
19,27,31 |
|
1.2.3 |
MS-3. Placement of Purchase Order of Reinforcement Steel at site |
0 days |
3FS+10 days |
9 |
|
1.2.4 |
Delivery of Reinforcement Steel at site |
5 days |
8 |
19,28 |
|
1.2.5 |
MS-4. Placement of Purchase Order of Bricks at site |
0 days |
3FS+10 days |
11 |
|
1.2.6 |
Delivery of Bricks at site |
5 days |
10 |
19,59 |
|
1.2.7 |
MS-5. Placement of Purchase Order of Sand at site |
0 days |
3FS+10 days |
13 |
|
1.2.8 |
Delivery of Sand at site |
2 days |
12 |
19,31 |
|
1.2.9 |
MS-13. Placement of Purchase Order for Aggregate at site |
0 days |
3FS+10 days |
15 |
|
1.2.10 |
Delivery of Aggregate at site |
5 days |
14 |
19,31 |
|
1.3 |
Construction Work |
353 days |
||
|
1.3.1 |
Site Preparatory work |
25 days |
||
|
1.3.1.1 |
MS-6. Start of Construction work at site |
0 days |
4 |
19 |
|
1.3.1.2 |
Site Office Set-up |
20 days |
18,7,9,11,13,15 |
20SS,22,25 |
|
1.3.1.3 |
Construction of Temporary Labor Camp |
15 days |
19SS |
21FF+5 days,22 |
|
1.3.1.4 |
Develop Reinforcement Bending Yard |
5 days |
20FF+5 days |
22,28 |
|
1.3.1.5 |
MS-7. Finish Site Prepartory work |
0 days |
21,19,20 |
|
|
1.3.2 |
Sub-Structure work |
207 days |
||
|
1.3.2.1 |
Building Foundation work |
28 days |
||
|
1.3.2.1.1 |
MS-8. Start Substructure work |
0 days |
19 |
26,27 |
|
1.3.2.1.2 |
Excavation for Raft Foundation |
3 days |
25 |
|
|
1.3.2.1.3 |
Pour Portland Cement Concrete |
2 days |
7,25 |
|
|
1.3.2.1.4 |
Fix Reinforcement Steel & Tie them together |
15 days |
9,21 |
29FF+5 days |
|
1.3.2.1.5 |
Place Formwork |
15 days |
28FF+5 days |
30 |
|
1.3.2.1.6 |
Quality Pre-Pour Check |
1 day |
29 |
31 |
|
1.3.2.1.7 |
Pour Concrete |
2 days |
30,7,13,15 |
33 |
|
1.3.2.2 |
Plinth Beam Work |
32 days |
||
|
1.3.2.2.1 |
Casting of one lift of column |
10 days |
31 |
34 |
|
1.3.2.2.2 |
Place reinforcement, formwork for plinth beam |
15 days |
33 |
35 |
|
1.3.2.2.3 |
Cast Plinth Beam |
2 days |
34 |
36 |
|
1.3.2.2.4 |
Backfilling & Compaction for Building area |
5 days |
35 |
46 |
|
1.3.2.3 |
Sanitary System |
58 days |
||
|
1.3.2.3.1 |
Deep Excavation |
3 days |
53 |
39 |
|
1.3.2.3.2 |
Construct Chambers |
30 days |
38 |
40 |
|
1.3.2.3.3 |
Connect Pipelines |
20 days |
39 |
41 |
|
1.3.2.3.4 |
Sand fill the Pipeline areas |
5 days |
40 |
42 |
|
1.3.2.3.5 |
MS-9. Finish Sub-Structure work |
0 days |
41 |
|
|
1.3.3 |
Super-Structure work |
223 days |
||
|
1.3.3.1 |
Construction of Frames |
147 days |
||
|
1.3.3.1.1 |
Ground Floor |
40 days |
||
|
1.3.3.1.1.1 |
MS-10. Start Super Structure work |
0 days |
36 |
47 |
|
1.3.3.1.1.2 |
Cast First Lift of column |
10 days |
46 |
48 |
|
1.3.3.1.1.3 |
Cast Second Lift of Column |
10 days |
47 |
49 |
|
1.3.3.1.1.4 |
Casting of last lift of column, beam and Slab |
20 days |
48 |
51,59FS+21 days,68FF |
|
1.3.3.1.2 |
First Floor |
49 days |
||
|
1.3.3.1.2.1 |
Cast First Lift of column |
12 days |
49 |
52 |
|
1.3.3.1.2.2 |
Cast Second Lift of Column |
12 days |
51 |
53 |
|
1.3.3.1.2.3 |
Casting of last lift of column, beam and Slab |
25 days |
52 |
38,55,60FS+21 days,69FF |
|
1.3.3.1.3 |
Second Floor |
58 days |
||
|
1.3.3.1.3.1 |
Cast First Lift of column |
14 days |
53 |
56 |
|
1.3.3.1.3.2 |
Cast Second Lift of Column |
14 days |
55 |
57 |
|
1.3.3.1.3.3 |
Casting of last lift of column, beam and Slab |
30 days |
56 |
61FS+21 days,70FF |
|
1.3.3.2 |
Brick Masonry work |
147 days |
||
|
1.3.3.2.1 |
Ground Floor |
20 days |
49FS+21 days,11 |
60,64FF-5 days,68FF,78,82 |
|
1.3.3.2.2 |
First Floor |
25 days |
59,53FS+21 days |
61,65FF-5 days,69FF,79,83 |
|
1.3.3.2.3 |
Second Floor |
30 days |
57FS+21 days,60 |
62,66FF-5 days,70FF,72FF+15 days,80,84 |
|
1.3.3.2.4 |
Parapet Wall |
10 days |
61 |
73 |
|
1.3.3.3 |
Fixing Fixtures |
127 days |
||
|
1.3.3.3.1 |
Fix Doors & Windows of Ground Floor |
10 days |
59FF-5 days |
|
|
1.3.3.3.2 |
Fix Doors & Windows of First Floor |
12 days |
60FF-5 days |
|
|
1.3.3.3.3 |
Fix Doors & Windows of Second Floor |
15 days |
61FF-5 days |
|
|
1.3.3.4 |
Conduit work |
122 days |
||
|
1.3.3.4.1 |
Ground Floor along with Slab casting |
5 days |
49FF,59FF |
74FF |
|
1.3.3.4.2 |
First Floor along with Slab casting |
7 days |
53FF,60FF |
74FF |
|
1.3.3.4.3 |
Second Floor along with Slab casting |
10 days |
57FF,61FF |
74FF |
|
1.3.3.5 |
Plumbing work |
50 days |
||
|
1.3.3.5.1 |
Biuld toilet & bathroom |
25 days |
61FF+15 days |
|
|
1.3.3.5.2 |
Fix Overhead Tanks |
5 days |
62 |
|
|
1.3.3.5.3 |
Provide Conduit Piping Work |
35 days |
68FF,69FF,70FF |
75FF |
|
1.3.3.5.4 |
Provide Fire Water point at each floor |
3 days |
74FF |
|
|
1.3.3.6 |
Plastering work |
142 days |
||
|
1.3.3.6.1 |
Internal |
137 days |
||
|
1.3.3.6.1.1 |
Ground Floor |
20 days |
59 |
86FF,91 |
|
1.3.3.6.1.2 |
First Floor |
20 days |
60 |
87FF,91 |
|
1.3.3.6.1.3 |
Second Floor |
20 days |
61 |
88FF,91 |
|
1.3.3.6.2 |
External |
142 days |
||
|
1.3.3.6.2.1 |
Ground Floor |
15 days |
59 |
92 |
|
1.3.3.6.2.2 |
First Floor |
20 days |
60 |
92 |
|
1.3.3.6.2.3 |
Second Floor |
25 days |
61 |
92 |
|
1.3.3.7 |
Flooring work |
132 days |
||
|
1.3.3.7.1 |
Ground Floor and Parking Area |
15 days |
78FF |
|
|
1.3.3.7.2 |
First Floor |
30 days |
79FF |
|
|
1.3.3.7.3 |
Second Floor |
30 days |
80FF |
|
|
1.3.4 |
Finishing work |
55 days |
||
|
1.3.4.1 |
Painting work |
25 days |
||
|
1.3.4.1.1 |
Internal Painting |
20 days |
78,79,80 |
93 |
|
1.3.4.1.2 |
External Painting |
20 days |
82,83,84 |
93 |
|
1.3.4.1.3 |
MS-11. Finish Super-Structure Work |
0 days |
91,92 |
95 |
|
1.3.4.2 |
Electrical Work |
15 days |
||
|
1.3.4.2.1 |
Cabling work |
12 days |
93 |
96 |
|
1.3.4.2.2 |
Fixing Lighting Fixtures |
3 days |
95 |
97 |
|
1.3.4.3 |
Punch listing |
5 days |
96 |
98 |
|
1.3.4.4 |
Finish Punch Listing work |
10 days |
97 |
99 |
|
1.3.4.5 |
MS-12. Handover to the Developer |
0 days |
98 |
The above relationships used are FF, FS & SS. FF means successor cannot finish unless its predecessor has completed, FS is the very common relationship between the activities, it means the successor cannot start until its predecessor completed. Now the SS is the successor cannot start unless its predecessor has started.
If anything is not mentioned in place of relationship that means it is FS relationship. The above diagram also shows that the moment A is completed, B can start.
It means the WBS 1.3.1.4 activity cannot finish before 5 days of lag after the completion of WBS 1.3.1.3 activity.
Determine activity durations for all trades, preliminaries, construction equipment, sheds, etc.
The major idea or methodology used to develop the schedule is by simply placing the activities one after another, and wherever parallel working is allowed as per sequence logic, it has also been considered to minimize the duration of construction. But at the same time when we perform parallel activities, the resource requirements raises to a very high numbers, which we shall study in next section.
So, we can conclude that by using above relationships among the activities, the start date if considered as Monday (May 22, 2017) then the finish date is arriving at Wednesday (October 10, 2018)
Resource requirements and durations: (opentextbc, 2017) & (Pmbook, 2017)
Let us assume there are below resources which are going to work for our project, the numbers required are not freeze yet, which we shall calculate in subsequent steps ahead.
|
Resource Name |
Type |
Initials |
Max. Units |
|
Concrete Mason |
Work |
C |
100% |
|
Carpenter |
Work |
C |
100% |
|
Unskilled Labor |
Work |
U |
100% |
|
Electrician |
Work |
E |
100% |
|
Plaster mason |
Work |
P |
100% |
|
Brickwork Mason |
Work |
B |
100% |
|
Flooring mason |
Work |
F |
100% |
|
Fitter |
Work |
F |
100% |
|
Reinforcement Fitter |
Work |
R |
100% |
|
Formwork Fitter |
Work |
F |
100% |
MSP could calculate on the basis of assigned resources to limited activities only. So the more accurate and exhaustive data we provide in MSP, the more accurate and reasonably usable data can be extracted.
All above resource mobilization plan is showing as some portion blue (which means 100% allocation) and anything above 100% means extra number of manpower is required to be mobilized to reduce over allocation and the HR / Admin / Contract department comes into picture to minimize the red color.
Even MSP also has a feature of minimizing the red color, by simply leveling the resources in such a manner that;
First choice is without delaying the final completion date of project and consuming the +ve float available between the activities which are not in critical path
Second choice is leveling with resource kept in mind and not the date.
So, we can conclude that by using above leveling tool, the finish date of the schedule has shifted from Wednesday (October 10, 2018) to Thursday (January 31, 2019). Delayed by 3 months but with some portion of resource leveling.
So from the above discussion we can conclude that the construction Manager need to take a smart call by calculating many other variable factors, that whether to target the date or cost (means resource) and act accordingly.
References / sources:
Mymanagementguide (2010). Project Constraints and Project Assumptions – A Planning Checklist. [Online]. Available at: https://www.mymanagementguide.com/project-constraints-and-project-assumptions-planning-for-project-success/ (Accessed 18 May 2017).
Learningtree (2012). Identifying Project Assumptions and Constraints. [Online]. Available at: https://blog.learningtree.com/identifying-project-assumptions-and-constraints/ (Accessed 18 May 2017)
Pmstudycircle (2017). Assumptions and Constraints in Project Management. [Online]. Available at: https://pmstudycircle.com/2012/10/assumptions-and-constraints-in-project-management/ (Accessed 18 May 2017).
Toolbox (2017). Lists of Assumptions & Constraints with a Sample. [Online]. Available at: https://it.toolbox.com/blogs/enterprise-solutions/lists-of-assumptions-constraints-with-a-sample-26073 (Accessed 18 May 2017).
Simplicable (2015). 7 Types of Project Assumptions. [Online]. Available at: https://simplicable.com/new/project-assumptions (Accessed 18 May 2017).
Stakeholdermap (2017). 22 Work Breakdown Structures (WBS). [Online]. Available at: https://www.stakeholdermap.com/plan-project/example-work-breakdown-structures.html (Accessed 18 May 2017).
Slideshare (2009). Wbs For Building Project. [Online]. Available at: https://www.slideshare.net/pmsmbsvit/wbs-for-building-project (Accessed 18 May 2017).
Workbreakdownstructure (2017). Work Breakdown Structure (WBS). [Online]. Available at: https://www.workbreakdownstructure.com/ (Accessed 18 May 2017).
sdc.wsu.edu (2017). Planning & Scheduling CSTM 462. [Online]. Available at: https://classes.sdc.wsu.edu/classes/cstm462/Lecture%203-Work%20Breakdown%20and%20Gnatt%20Charts.pdf (Accessed 18 May 2017).
Bnl (2003). Work Breakdown Structure. [Online]. Available at: https://www4.rcf.bnl.gov/~videbaks/hft/cd1/DOE_guidance_wBS.pdf (Accessed 18 May 2017).
Management (2017). Sequence Acivities & Develop Schedule. [Online]. Available at: https://free-management-ebooks.bmobilized.com/?ref=android-app%3A%2F%2Fcom.google.android.googlequicksearchbox&url=http%3A%2F%2Fwww.free-management-ebooks.com%2Ffaqpm%2Fschedule-03.htm&width=393 (Accessed 18 May 2017).
Thebalance (2016). Understanding Project and Task Dependencies. [Online]. Available at: https://www.thebalance.com/project-and-task-dependency-in-project-management-2276123 (Accessed 18 May 2017).
Opentextbc (2017). 11. Resource Planning. [Online]. Available at: https://opentextbc.ca/projectmanagement/chapter/chapter-11-resource-planning-project-management/ (Accessed 18 May 2017).
Pmbook (2017). 9. Construction Planning. [Online]. Available at: https://pmbook.ce.cmu.edu/09_Construction_Planning.html (Accessed 18 May 2017).
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