Crashing Program and Project Scheduling

CRASHING PROGRAM AND PROJECT SCHEDULING A. Crashing Program In preparing a construction project schedule, an ideal schedule is usually not immediately produced, one of the objectives of preparing a schedule is to produce a realistic schedule based on reasonable estimates. Many times the determination of the duration of a project is determined by the project owner without considering the type of activity and the complexity of the work. This makes the scheduler adjust the duration of each job in order to meet the project owner's request, so that it can produce an inefficient and sometimes unrealistic schedule, such as shifts in the implementation of work, overtime work or deploying workers in large groups. The crashing process is a way of estimating cost variables in determining the maximum reduction in duration with the most economical cost of activities that are still possible to be reduced (Ervianto, 2004). Crashing is done so that the work is completed with a cross-exchange of time and costs by increasing the number of work shifts, the number of working hours, the number of workers, the amount of material availability and using more productive equipment and faster installation methods as cost components (direct costs). As for Crashing program according to Badri (1997), namely in a project that is desired to be completed within a specified time, the duration of the activity can be accelerated with the consequence of experiencing an increase in costs. Most projects describe the relationship between cost and time as a straight line. Figure 3. Relationship between time and cost Point (Dn, Cn) states the relationship between time Dn and cost Cn if the activity is in normal condition. There is a limit called crash time or crash limit (acceleration time limit) which states that the next time reduction (which exceeds this limit) will no longer be effective. This time reduction will only be effective if the time on the critical activity is reduced, so what needs to be considered is the activity that is on the critical path. In order to obtain a time reduction with the smallest cost. So, the job indicator that can be selected for acceleration is the job with the smallest cost slope value. Because the smallest cost slope value interprets the smallest cost increase. B. Crashing Program Analysis In accelerating the project duration, it is usually done on jobs that have a critical path. Because the activities that have a major influence on the project are on the critical path. The provisions of the plan for this alternative increase in working hours are as follows: 1. Normal working hours are 8 working hours per day (08.00 - 17.00) with 1 hour of rest (12.00 - 13.00), while overtime work is carried out after normal working hours for 3 hours per day (18.30 - 22.30). In a week, only 6 working days are carried out, namely Monday - Saturday. 2. According to the Decree of the Minister of Manpower Number: KEP.102 / MEN / VI / 2004 article 11, wages for working hours (overtime) are calculated as follows: a) For the first 1 hour of overtime work, the wage to be paid is 1.5 times the hourly wage. b) For each subsequent hour of work, the wage to be paid is 2 times the hourly wage. 3. Productivity for overtime hours is calculated at 60% of normal productivity Calculation of Daily, Normal and Accelerated Productivity Accelerated daily productivity is obtained from the sum of normal daily productivity with work productivity during overtime hours per day. The addition of overtime hours according to applicable regulations is carried out for 3 hours per day, while the productivity of overtime workers is assumed to have decreased, and is only calculated at 80% of the productivity of regular working hours. The steps for calculating accelerated daily work productivity are as follows: a) Calculating work volume b) Calculating normal duration c) Calculating normal daily productivity d) Normal productivity/hour e) Overtime hour productivity f) Accelerated daily productivity C. Project Scheduling The objectives of scheduling are as follows: a) Facilitate the formulation of project problems. b) Determine the appropriate method or method. c) Smooth activities are more organized. d) Get optimum results. While the functions of scheduling in a construction project include: a) Determine the total duration needed to complete the project. b) Determine the implementation time of each activity. c) Determine activities that must not be late or delayed in their implementation and determine the critical path. d) Determine the progress of project implementation. e) As a basis for calculating project cash flow f) As a basis for scheduling project resources, such as labor, materials, and equipment. g) As a project control tool.