Ch 8 Solution

3. Compute the early, late, and slack times for the activities in the network that follows, assuming a time-constrained network. Which activities are critical? What is the timeconstrained project duration? Note: Recall in the schedule resource load chart the “time constrained”schedule interval (ES through LF) has been shaded. Any resource schedule beyond the shaded area will delay the project. Without consideration of resources the project is estimated to take 13 time units and the critical path is 246 (see Network Diagram). Assume you have only three resources and you are using a computer using a computer that uses software that schedules projects by the parallel method and following heuristics. Schedule only one period at a time! Minimum slack Smallest duration Lowest identification number Keep a log of each activity change and update you make each period—e.g., period 0-1, 1-2, 2-3, etc. (Use a format similar to the one on page 241.) The log should include any changes or updates in ES and slack times each period, activities scheduled, and activities delayed. (Hint: Remember to maintain the technical dependencies of the network.) Use the resource load chart to assist you in scheduling (see pages 242-243). List the order in which you scheduled the activities of the project. Which activities of your schedule are now critical? Recompute your slack for each activity given your new schedule. What is the slack for activity 1? 4? 5? Log of Parallel Method of Scheduling 8-3 PERIOD ACTIVITY CHANGES 0-1 2 Schedule Activity 2 (first by minimum slack rule) 1 Schedule Activity 1 3 Delay Activity 3 ES to period 1. Reduce slack to 0 5 Delay Activity 5 ES to period 6. Reduce slack to 0 1-2 3 Delay Activity 3 ES to period 2. Reduce slack to -1 5 Delay Activity 5 ES to period 7. Reduce slack to -1 6 Delay Activity 6 ES to period 11. Reduce slack to -1 2-3 3 Delay Activity 3 ES to period 3. Reduce slack to -2 5 Delay Activity 5 ES to period 8. Reduce slack to -2 6 Delay Activity 6 ES to period 12. Reduce slack to -2 3-4 3 Schedule Activity 3 4-5 4 Schedule Activity 4 5-6 No changes 6-7 No changes 7-8 No changes 8-9 5 Schedule Activity 5

Log of Parallel Method of Scheduling 8-3 (continued) PERIOD ACTIVITY 9-10 No changes 10-11 No changes 11-12 No changes 12-13 6 Schedule Activity 6

CHANGES

4. You have prepared the following schedule for a project in which the key resources is a tractor. There are 3 tractors available to the project. Activities A and D require 1 tractor to complete while Activities B, C, E and F require 2 tractors. Develop a resource-constrained schedule in the loading chart that follows. Use the parallel method and heuristics given. Be sure to update each period as the computer would do. Record the early start (ES), late finish (FL) and slack (SL) for the new schedule.