Resource Hiring
5.7 Allocate Resources to Project Plan
Now, we want to distribute the available resources at different stages of the project and the scheduled plan is obtained after the work of planning for the project as a whole is performed. Then, allocate the resources you have on the activities of the project. This will be explained in the following example.
5.7.1 Example
We will use the same example as discussed previously in Chapter 4 for time management. The project is to install a mechanical package and connect it with piping as shown in Table 5.1. From this table we can define the rela- tionship between the project activities.
Figure 5.6 shows the critical path of this project through the project plan. Table 5.2 shows the early and late times for the beginning and end of each activity and the time which any activity can move within Table 5.1 Example for foundation.
Item Activity Time (days) Precedence activity
100 Mobilization 3 –
200 Excavation 8 100
300 Pouring concrete foundation and piping support
10 200,100
400 Install the piping 4 300,100
500 Install the mechanical package 1 300
600 Put the grouting 1 300, 500
700 Connect the piping 5 400,500
800 Commissioning and start up 2 700
itself and the overall time. An activity can move through itself without affecting the overall time for the project and it is presented in the table by the total floating time (TF). The column of the resources shows the number of personnel required for each activity per day, while the last column shows the total number of days required for each activity. For example, in Table 5.2 excavation needs seven workers per day and work will last for eight days, so this activity needs 56 working days in order to be achieved.
Figure 5.6 Preceding diagram define the critical path.
100 200 600
400
3 7
14 18
7 12
18 23
0 3
0 3
3 11
3 11
11 21
11 21
21 22
21 22
22 23
22 23
23 25
23 25
300 500
700
800 Pouring concrete
Excavate
Install piping
Mech. package Put grouting
Conn. piping
3 8 1
4
10 1
5
Comm.& start up 2 Mob.
Table 5.2 Resources allocated to the activities.
No. Activity D Earliest Latest Float Resources per day
Total resources ES EF LS LF TF FF
100 Mobilization 3 0 3 0 3 0 0 4 12
200 Excavation 8 3 11 3 11 0 0 7 56
300 Pouring concrete foundation and piping support
10 11 21 11 21 0 0 4 40
400 Install piping 4 3 7 14 18 11 11 5 20
500 Install the mechanical package
1 21 22 21 22 0 0 4 4
600 Put the grouting 1 22 23 22 23 0 0 4 4
700 Connect the piping
5 7 12 18 23 11 11 5 25
800 Commissioning and start up
2 23 25 23 25 0 0 6 12
Total projects man days 173
Figure 5.6 shows the distribution of the time duration of this project which is 25 days. When summing the total number of working days, as shown in Table 5.2, it will be 173 working days.
Figure 5.7 presents the time schedule and the number of employees. If the plan is presented by the early start, it means all activity will start in its first time to start. In the bottom of the schedule, the other option is to do all the activity in the latest start time, which means all the activity which is not on the critical path will be starting at its latest time. In our example here, the two activities are 400 and 700 for installing the piping and connecting the piping, respectively.
In the first case, the maximum number of persons on site will be twelve, whereas in the second option, for the latest start, the maxi- mum will be nine persons. Therefore, a decision needs to be made on whether to use the total float or free float to achieve the project target.
In normal cases, if the number of laborers will be less, the impact will be good, but if there is an increase in the laborers, the probability of incidents and injury will increase. We can look at it from another view as in remote areas, which are normal in the case of oil and gas projects, the accom- modation will be difficult and expensive. So, if you maintain a minimum number of employees, it will have a good impact on the cost and, in some cases, it will be a constraint if the client provides accommodation for only ten persons per day.
In the case of the engineering design office, it is important to distrib- ute the work load, as it will be very good to not hire engineers to work for part time for only six month, rather than hire the full time engineers.
Distributing the work load by this philosophy is very beneficial
Figure 5.7
25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 Res. Activity 4 Mobilization 7 Excavation 4 Pouring conc.
4 Mech. packg 4 Grouting 6 Comm & start up 5 Install piping 5 Connect piping
6 6 4 4 4 4 4 4 4 4 4 4 4 9 12 12 12 1212 12 12 12 4 4 4 Sum
5 Install piping 5 Connect piping
6 6 9 9 9 9 9 9 9 9 9 4 4 4 7 7 7 7 7 7 7 4 4 4 4 Sum
Figures 5.8 and 5.9 represent the distribution of the resources in two cases and the harmony of resources distribution is visible if we use the latest start activity as discussed before.
It is worth mentioning here that, in the case of large projects, a meeting must be held between a representative of the owner, the consultant, and the contractor.
In this meeting, the contractor should define the personnel and equip- ment that will be found at the site in accordance with the scheduled plan.
In this meeting, all the representative engineers should agree on the resources.
Noting that, each party will distribute resources according to its own benefits. As an example, the contractor in the negotiation will have had more than one reason for the distribution of resources, advertising and most other causes are undeclared as he may need some personnel for another project at a particular time or need to transport heavy equipment, such as cranes, to another site or other important resources. At the same time, he wants to delay some of the items to be cost assembled in another project and this will be studied in the chapter on costs.
From the owner point of view, it is important to complete all the items as soon as possible. The owner often does not want to consume all the
Figure 5.8 Resources distribution in first case.
0 4 8 12
1 2 3 4 5 6 7 8 9 10 11 12 13 14 1516 17 18 100
Resources unit
200 300 800
19 20 21 22 23 24 25
400 700
500 600
Days
Figure 5.9 Resources distribution by latest plan.
0 4 8 12
1 2 3 4 5 6 7 8 9 10 11 12 13 14 1516 17 18 100
Resources unit
200 300 800
19 20 21 22 23 24 25
400 700
500 600
Days
time, which could be moved to minimize the risks to the project and use a higher employment rate in the start, which will lead to a less likely risk for project delay.