1. CE 366 PROJECT MANAGEMENT AND ECONOMICS Robert G. Batson, Ph.D., P.E. Professor of Construction Engineering The University of Alabama

2. Chapter 7: Project Time Acceleration

3. Sources of Need For Project Time Reduction
Overall Project
Planned schedule will not meet contracted completion date
Owner requests quotation to finish work early
Contractor has reasons to finish early
Work underway, delays have occurred, need to recover lost time
Milestone Event
Computed timing of event is later than desired
Network interface requirement
Need to recover lost time by the milestone
Removing “Project Contingency” is not the way to accelerate the project

4. Project Time Reduction (Acceleration)
Also known as
Least-cost expediting
Project compression
Activity time-cost trade-off or “crashing”
Does not require expediting all project activities (shotgun approach)
To reduce the project completion time, the project critical path must be shortened
To reduce the time to achieve a milestone or interface event, the event critical path must be shortened
As critical activities are accelerated to shorten critical path(s)
The floats along all paths to the accelerated activity change
The critical path eventually changes (hence activities may change from non-critical to critical, or vice versa)
Second critical path may emerge, or disappear

5. Shortening the Longest Time Path
Two ways to accomplish shortening
Modify the job logic, such that the longest path is reduced
Rearrange order of activities
Split activities into two
Revise lag time logic
Reduce the time duration (crash) one or more critical path activities
Increased manpower or overtime work
Additional equipment
Computerized time-cost trade-off analysis will actually find the most efficient sequence of such activity time reductions, with input such as Figure 7.1
Remember, after each logic or activity duration adjustment, the critical path and float times must be recomputed.

7. Handling Direct Cost Increases in Project Acceleration Study
Direct cost of an activity is made up of the expense of labor, equipment, materials and subcontracting
Each activity is assumed planned at its “normal cost” and “normal duration”
Any variation in an activity time from that estimated, either more or less, will result in a commensurate increase in its direct cost
An activity that is feasible to accelerate (crash) will have a “crash cost” and “crash time” as in Figure 7.1
The least total direct cost for the project is the cost associated with the normal project duration (as estimated by CPM)
If the project duration is to be reduced, the direct costs of the activities actually shortened will usually be increased; therefore the total direct cost will increase as well.

8. Estimating Indirect Cost Decreases in Project Acceleration Study
If a specific activity is shortened, its direct expense increases, but if it leads to a corresponding decrease in overall project duration, the indirect cost is reduced
There are two types of project indirect costs
Time-constant overhead expense
Time-variable overhead expense
For the highway bridge, each day reduction from the normal schedule (70 days) is worth $43,690/70 = $624 reduction in overhead

9. Shortening the Critical Path at No Extra Direct Cost
Restudy of Critical Activity Duration
Error could be discovered
Original time estimates based on invalid assumptions
Restudy of Project Plan
Rework project logic
Modify the design (in design-build)
Critical Activities in Parallel, not Series
Subdivision of Critical Activities, with new logic
Subcontracting, if it substitutes workers/equipment at same direct cost yet enables activities to overlap
Items B, C, D require scheduler to use personal
technical knowledge or obtain inputs from experts,
individually or in team meetings

12. Shortening the Critical Path by Expediting
Expediting actions, such as those in Figure 7.4, involve additional direct cost
some involve adding an activity, that changes the network logic in a favorable way, such as Action A which saves 6 days
others involve accelerating a particular activity by expending direct activities
Figure 7.5 organizes the actions from smallest to largest increment in direct cost, and show cumulative direct costs (also see Figure 7.6)
Figure 7.7 shows overhead cost reduction, project direct cost increase, and project direct cost + overhead, as a function of time

17. Significance of Project Time-Cost Trade-Off Curve
What durations yields minimum cost to the contractor?
If normal plan dictates a late completion, and daily penalties are known, how much expedited cost is justified; that is, what duration best balances costs with penalty avoidance?
Owner may ask for a range of price quotes, one for each completion time
What are the limits that may be achieved by expediting?
Some of the most useful CPM-based information the scheduler/estimator can provide to the project manager

18. Project Extension
Projects, of course, experience “slippage” in milestone or completion dates, if the project actualization does not match the plan
The usual rule is that projects whose end dates slip will cost more, in direct cost of those activities that took longer than planned, and in overhead costs
Sometimes projects are estimated using some or all activities at their expedited (crash time) limits, and this anticipated action proves unnecessary once the CPM schedule is developed and evaluated
Some of these activities can be relaxed to their normal time and cost
Critical path activities if project duration can be extended
Non-critical path activities if project duration is held