Crash management
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The project has 8 activities with normal and crash durations and costs provided. The contract time is 20 days with a penalty of 300 LE/day for delays. To meet the contract time, activities XE, YC, and ZA need to be crashed. Crashed costs are 1140 LE, 1470 LE, and 770 LE to finish in 23, 22, and 21 days respectively. The optimal plan is to crash for 1140 LE to finish in 20 days as required. After a site update on day 5, the project is expected to finish in 22 days. Activities Y and Z are already complete. Crashing activity D for 1000 LE and activity B for 700 LE, for a
Crash management
- 1. Crash Activity Successor Normal duration Crash duration Normal cost (LE) Crash Cost (LE) Constraint Z A 4 2 2660 2800 - A B,D 10 7 5000 5750 - B - 5 3 3500 4900 F4,D2A D - 8 6 7150 8150 D3C,L4E E D 10 6 2800 3200 D5X X E 4 2 4000 4300 F5 Y C 5 5 5000 5000 F5 C D 7 4 5000 5600 - A project has the following activities and relationships Contract time 20 days, Penalty Value300 LE/Day, What is your recommendation?
- 2. Finish X C E Y AZ B D Start 4 0 5 5 0 5 10 10 20 7 5 12 0 0 0 4 0 4 10 4 14 5 16 21 8 16 24 0 24 24 F5 L4 D3 D5 D2 F5 Activity Successor Z A A B,D B - D - E D X E Y C C D 15 16 14 24 21 F4
- 3. If we don’t crash the project the total cost will be as following : Total cost = Total normal cost + Penalty cost Total normal cost = Ʃ Normal cost for each activity =2660+5000+3500+7150+2800+4000+5000+5000= 35110 L.E. Penalty cost = Penalty cost per month * No. of delayed month = 300 * 4 = 1200 L.E. Total cost = Total normal cost + Penalty cost = 35110 + 1200 = 36310 L.E. In This case total time of the project will be 24 w and Contractor will deliver the project 4 month later than the time in the contract. To avoid this delay the crash will be applied to this network to deliver the project as possible as contract time.
- 4. The Crash rules : 1) Apply Crash only on activities which affect the total time. 2) Crash the least cost activity according to the least cost slope Cost Slope = 𝑪𝒓𝒂𝒔𝒉𝒆𝒅 𝒄𝒐𝒔𝒕 𝑪.𝑪. −𝑵𝒐𝒓𝒎𝒂𝒍 𝑪𝒐𝒔𝒕(𝑵.𝑪.) 𝑵𝒐𝒓𝒎𝒂𝒍 𝑫𝒖𝒓𝒂𝒕𝒊𝒐𝒏 (𝑵.𝑫.) −𝑪𝒓𝒂𝒔𝒉𝒆𝒅 𝑫𝒖𝒓𝒂𝒕𝒊𝒐𝒏 (𝑪.𝑫.) L.E unite time 3) Activity will be crashed according to it’s crashability Crashability = Normal Duration(N.D.) – Crash Duration (C.D.)
- 5. The Path which need to be crashed are the paths gives total time more than contract time (20 w) X E D (24w 20w) 2 500 4 100 Y C D 2 500 3 200 Z A D 2 500 3 250 2 70 (23 20) (22 20) Z A B 1 700 3 250 2 70 (21 20) 4E = 4*100 = 400 L.E. 3C = 3 * 200 = 600 L.E. 2Z = 2 * 70 = 140 L.E. This path is already crashed 2Z from the previous path (Z is Shared activity in the two paths) Total Crashed Cost = 600 + 400 + 140 = 1140 L.E.
- 6. Another Scenario to reach contract time 20 w X E D (24 20) 2 500 4 100 Y C D 2 500 3 200 Z A D 2 500 3 250 2 70 (23 20) (22 20) Z A B 2 700 3 250 2 70 (21 20) 1C = 1 * 200 = 200 L.E. NO need for crashing this path 1Z = 70 L.E. 2E = 2 * 100 = 200 L.E. Act. D is shared Act. 2D = 2*500= 1000 L.E. Total Crashed Cost for this scenario = 1000 + 400 + 200+70 = 1470 L.E.
- 7. X E D (24w 23w) 2 500 4 100 Y C D 2 500 3 200 Z A D 2 500 3 250 2 70 (23 23) (22 23) Z A B 1 700 3 250 2 70 (21 23) Total Crashed Cost = 100 L.E. 1E = 1 * 100 = 100 L.E. NO need for crashing this path NO need for crashing this path NO need for crashing this path Scenario of ending the project with in 23 w
- 8. X E D (24w 22w) 2 500 4 100 Y C D 2 500 3 200 Z A D 2 500 3 250 2 70 (23 22) (22 22) Z A B 1 700 3 250 2 70 (21 22) Total Crashed Cost = 200 + 200 = 400 L.E. 2E = 2 * 100 = 200 L.E. 1C = 200 L.E. NO need for crashing this path NO need for crashing this path Scenario of ending the project with in 22 w
- 9. X E D (24w 21w) 2 500 4 100 Y C D 2 500 3 200 Z A D 2 500 3 250 2 70 (23 21) (22 21) Z A B 1 700 3 250 2 70 (21 21) Total Crashed Cost = 300 + 400 + 70 = 770 L.E. 3E = 3* 100 = 300 L.E. 2C = 2 * 200 = 400 L.E. 1Z = 70 L.E. NO need for crashing this path Scenario of ending the project with in 21 w
- 10. Total time Total Normal Cost Total crashed cost Total Penalty Value Total cost 24 35110 0 1200 36310 23 35110 100 900 36110 22 35110 400 600 36110 21 35110 770 300 36180 20 35110 1140 0 36250 Scenarios of the different completion time of the project can be estimated according to this table: Respect reputation and apply scenario 20 w
- 11. Finish X C E Y AZ B D Start 4 0 5 5 0 5 10 16 4 5 9 0 0 0 2 0 2 10 2 12 5 14 19 8 12 20 0 20 20 F5 L4 D3 D5 D2 F5 12 12 12 20 19 F4 6 The final executed Network
- 12. UPDATE Feedback form site at day 5 as following: 1) Activity C will start late by 2days 2) Activity A will finish late by 2 days Finish X C E Y AZ B D Start 4 0 5 5 0 5 10 16 4 7 11 0 0 0 2 0 2 10 2 14 5 16 21 8 14 22 0 22 22 F5 L4 D3 D5 D2 F5 14 12 14 22 21 F4 6
- 13. According to feedback at day 5 during construction the project will finish in 22 day (2 days late from contract time) , so we need to apply crash again but take in your consideration : 1) The activities which have been finished. Ex: Activity X,Y and Z finished before the feedback date and Activity C not started yet according to feedback (not allowed to be crashed) and Activity A has been started but will finish late according to feedback (allowed to be crashed if possible). 1) The activities which have been crashed before. Ex: Activity E,C and Z
- 14. Y C D 2 500 0 200 Z A D 2 500 3 250 0 70 (22 20) (22 20) Z A B 1 700 3 250 0 70 (21 20) 2D = 2 * 500 = 1000 L.E. This path is already crashed 2D from the previous path (D is Shared activity in the two paths) 1B = 1 * 700 = 700 L.E. Total Crashed Cost = 1000 + 700 = 1700 L.E.
- 15. The network after update Finish X C E Y AZ B D Start 4 0 5 5 0 5 10 16 4 7 11 0 0 0 2 0 2 10 2 14 4 16 20 6 14 20 0 20 20 F5 L4 D3 D5 D2 F5 14 12 14 20 20 F4 6