Calculating the Activity Time Period
The calculation of the activity period requires taking data from different disciplines, but its accuracy depends on the skill and strong experience of the planner. On the other hand, there is a performance rate for each activity, and in the international contractor companies usually have a standard guide for the performance rate for each activity.
There are many factors that affect the labor productivity:
• Job size and complexity
• Job site accessibility
• Labor availability
• Equipment utilization
• Contractual agreements
• Local climate
• Local cultural characteristics, particularly in foreign operations
There is a method for calculating the time of an activity through the use of performance rates. Below shows the method of calculating the period of time to excavate 15,000 m3, and this requires, first, determining the method of excavation. In this example, it has been identified by the equipment.
Assume you need to excavate 15,000 m3 of soil. Using 2 bulldozers and loaders and trucks to transport the disposal will be the method of excavation. The equipment used will be 2 bulldozers, 2 loaders, and 4 trucks. The performance rate for 1 bulldozer is 120 m3/hour, and the performance rate for 1 loader and 2 trucks is 75m3/hour.
The rate of excavation = 2 x 120 = 240 m3/hour.
The required time for excavation = 15,000/240 = 62.5 hours = 9 days.
The rate for removing disposal = 2 x 75 = 150 m3/hour.
The time period for removing disposal =15,000/150 =
100 hours = 15 days.
Therefore, the excavation time equals about 9 days, and the transfer of residue is approximately 15 days, taking into consideration that the number of working hours in the day equals only 7 hours in the preparation of the timetable. For the excavation activity, take the largest time period, which is 15 days. But it may be after finishing the excavation is to start pouring the plain concrete, so it will start after 9 days, as there is no need to wait pouring the concrete until transfer all waste from the site.