Scheduling in Construction Management

 

Scheduling in Construction Management

Modern construction relies on scheduling software to automate and refine project schedules. These tools help streamline calculations and ensure accurate timelines. Let’s dive into some key concepts, starting with precedence network diagrams.

---

What is a Precedence Network Diagram?

A precedence network diagram is a graphical representation of project activities, showing their order and dependencies.

• Nodes: Represent individual activities.
• Logical Lines: Connect the nodes, indicating the sequence of activities.
• Duration: Assigned to each activity.

This diagram forms the backbone of project scheduling, helping to visualize how tasks are interconnected.

---

Key Terms in Scheduling

1. Early Start (ES):

The earliest time an activity can begin, based on dependencies in the network diagram.

2. Early Finish (EF):

The earliest time an activity can finish, calculated as:
$\text{Early Finish} = \text{Early Start} + \text{Duration}$

3. Late Start (LS):

The latest time an activity can begin without delaying the overall project. This ensures the project stays on schedule.

4. Late Finish (LF):

The latest time an activity can finish without affecting the project's completion date, calculated as:
$\text{Late Finish} = \text{Late Start} + \text{Duration}$

---

Float (Slack)

Float is the amount of time an activity can be delayed without affecting the overall project schedule.

Types of Float:

1. Total Float:

   • The total time an activity can be delayed without delaying the entire project.

2. Free Float:

   • The time an activity can be delayed without delaying the start of subsequent activities.

Ownership of Float: Ownership of float time should be specified in the contract to avoid disputes between contractors and owners.

---

Critical Path

The critical path is the sequence of activities that must be completed on time for the project to finish as scheduled.

• Delays in any critical path activity will directly impact the project’s completion date.

---

Working Days vs. Calendar Days

Working Days:

• Exclude weekends and national holidays.
• Activities are scheduled Monday through Friday unless otherwise specified.

Calendar Days:

• Include all days in the calendar, including weekends and holidays.

Scheduling Software: Modern tools allow you to define what constitutes a working day and adjust for project-specific constraints. This ensures accurate plotting and scheduling of activities.

---

Work Packages

A work package is the smallest unit of work in a project schedule.

• Contents of a Work Package:
  • Activities
  • Duration
  • Cost
  • Resources

Why Use Work Packages?
Breaking the project into manageable units allows:

• Accurate scheduling.
• Clear assignment of responsibilities.
• Easy tracking of progress.

---

Procurement and Float Management

Procurement Activities

Activities like ordering materials with long lead times (e.g., structural steel) that, if delayed, can impact the project timeline. Early scheduling ensures timely delivery.

Float Management

Disagreements about float ownership can arise if contracts don’t specify who controls float time. Always address this in contracts to avoid disputes.

---

Conclusion

Scheduling is a critical aspect of construction management, involving tools like precedence network diagrams and concepts like critical paths, float, and work packages. By leveraging modern software and clear planning, construction managers can ensure timely and efficient project completion.

Pooja Mattapalli