Analysis of the tidal wave occurrence on port project duration using crash and track method (case study: Sanur Port, Bali, Indonesia)

One of the main risks that can influence the duration of port projects is the tidal waves. Tidal waves can disrupt the work and cause delays. This study analyzes when a tidal wave occurs and how much it affects the delay in the Sanur Port Project. Based on these results, several scenarios of duration acceleration were carried out using the crashing and fast track methods. The results showed that the planned duration was 819 days, whereas due to the tidal wave, the project duration increased from 98 to 917 days. The first acceleration scenario, using the crashing method with 2 h of overtime, resulted in a new duration of 783 days or 36 days faster than the planned duration. The second acceleration scenario with the fast-track method resulted in 770 or 49 days faster than the planned duration.


Background
One of the goals of sustainable development Goals (SDG) is to build resilient infrastructure by mitigating the risk of infrastructure.Natural factors such as bad weather and wave height can cause project delays if they are not considered [1].According to Maysara et al. [2], tidal waves can cause project delays up to 16% of the planned duration.
The implementation of a construction project requires good planning, scheduling, and control.Planning is an activity carried out in a project to anticipate existing tasks and conditions by setting goals and objectives, one of which is a timely implementation schedule.To achieve this goal, project scheduling is required.Project scheduling is performed to determine the length of project activities to be completed, raw materials, labor, and time required by each activity [3].Scheduling is one of the most important aspects of port projects.Natural factors such as bad weather and wave height can cause project delays if they are not considered [2].According to Maysara et al. [3], tidal waves can cause project delays up to 16% of the planned duration.
Sanur Beach is in the southeastern part of Bali Island, which is an area directly adjacent to the Indian Ocean.Waves in the Indian Ocean, especially Bali Province, have a height of 1.5-2 m which are included in the medium category of waves [4].In extreme weather, the wave height of the Indian Ocean in Bali Based on this, a project schedule acceleration scenario was carried out to avoid delays in the project duration.Schedule expediting is generally defined as early modification of plans and/or schedules to complete critical tasks or projects.Schedule compression is the rescheduling of tasks with minimal or no impact on cost [5].Two general methods are used to accelerate the project schedule: crashing and fast tracking.Crashing is an analytical method used to shorten the duration of a project's activities, where crash activities are on the critical path.The purpose of the crash method is to speed up the project time with minimum additional costs.Several scenarios that can speed up the completion of time include increasing the number of hours worked (overtime work) and adding more workforce and tools.These methods can be carried out separately or in combination, for example, a combination of increasing working hours and increasing the number of workers or (shifts) [6].At the same time, the fast-track method is an acceleration method in development that implements parallel/overlapping activities on the project's critical path so that the implementation time is faster, and costs are more efficient [7].

Literature Review
Some of the previous studies that were used as the basis for this research include the following.a.The Monte Carlo Simulation and critical path methods were used to determine the project duration.
The total duration of MCS use was 775 days, whereas that of the CPM method was 775 days.The difference in results is because, in the CPM method, there is only one important path, whereas in the MCS method, there are several calculations of project uncertainty [2].b.Research on Mediterranean waves with a height of 1.00 meters reaching 50%, occurred in October and November, resulting in delays in the project duration, reaching 16.2% of the planned duration.
A wave height of 1.5 meters has a 20% probability of occurrence in winter, which can cause project delays of 5% of the planned duration [3].c.The duration of the project plan for breakwater types D and 1 B was 1500 d with a total cost of Rp 9,017,853,688,889.76.Alternative acceleration is carried out using the addition of tools, human resources, overtime hours, and a combination of the three.The project can be completed as planned with a combination of the three, with a total duration of 390 days and an additional cost of Rp. 78.001.557.826.86 [8].

Methodology
The research was conducted based on data obtained from projects such as the S Curve, duration of each activity, work volume and wave data from 2010 to 2020.First, an analysis of the project work sequence consisting of five jobs was conducted: south breakwater work, north breakwater, embankment installation, dredging harbor ponds, and floating dock works.Then, a network or network diagram was compiled to determine the critical path and total duration of the plan.Subsequently, wave frequency analysis was carried out to determine when the tidal wave occurred at a height of 2.5 m or more.Subsequently, a new project schedule was created owing to the tidal waves, which caused delays.
Therefore, an analysis of the duration acceleration was performed using the crashing and fast track

Work Sequence
The analysis was performed based on the S curve of the project.The sequence starts from the preparation work, then the south breakwater work, followed by the north breakwater and the installation of the embankment, dredging, and floating dock work.

Network Planning
Network analysis was performed using the Presence Diagram Method (PDM).Network analysis was performed to determine the critical path and the total duration of the plan.In addition, the network makes it easier to plan and control the project activities.In creating a network, it takes the type of activity to be carried out, the relationship between activities and the duration of each work

Critical Path
The critical path analysis is determined from the forward and backward passes.The forward pass determines the earliest time an activity starts (earliest start), and the earliest time an activity is finished (earliest finish).While the backward pass is to determine the latest time for an activity to start (latest start) and the latest time for an activity to finish (latest finish).The wave data used were 11 years of data from 2010 to 2020 based on observations from the Benoa Station.Then, an analysis of the frequency of tidal waves was carried out every week, as shown in Table 3.

Month
Weeks (Times)

New Schedule Based on Tidal Waves
After determining the tidal wave, the wave parameters were arranged into a schedule so that there were activities that were delayed.Below are the activities that were delayed by tidal waves, as shown in Table 4.

Crashing Method
After that, an analysis of the acceleration of duration was carried out with the addition of 1, 2, and 3 hours of overtime.Table 5 shows the results of the duration after acceleration.The total duration of the project after adding 2 hours of overtime on the critical path can be accelerated by 36 days to 783 days, or 112 weeks.The project duration was five weeks shorter than the plan, which was 819 days.The total duration of the project after overlapping work on the critical path can be accelerated by 49 days to 770 days, or 110 weeks.The project duration was seven weeks ahead of the planned schedule of 819 days as shown in Table 6.

Conclusion
Based on the results of the analysis, the following conclusions were drawn: a. Tidal waves are expected to occur as follows: a. April: 3 rd week.b.May: 3 rd week c.October: 3rd and 4 th weeks d.November:1 st and 4t h week e.December: 1 st week.b.The total project delay due to the waves was 98 or 14 weeks from the planned schedule.The work that was delayed owing to the addition of seawater wave parameters included the following: • Stone Installation 500 -1000 kg (South Breakwater): 14 days.

3 methods.Figure 1 .
The crashing method is performed by adding overtime hours of 1, 2, and 3 h, whereas the fasttrack method overlaps the activities.The next step is to draw up a new project schedule owing to acceleration and compare the results.Finally, conclusions and suggestions are presented.(a) location; (b) south breakwater; (c) north breakwater; (d) revetment; (e) dredging; (f) pier 4. Analysis

Table 1 .
Project Critical Path

Table 4 .
Duration of Activities Affected by Tidal Waves

Table 6 .
Fast Track Duration