Time-Cost Trade off

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Often projects main constrains are time and cost

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Time-Cost Trade off

  1. 1. Time-Cost Trade-off Course title: BLDG 6801 Professor Khaled El-Fekhfakh Presented by: Group 1 Mohamed Fared Zuhri Yafi 9762132 1
  2. 2.  Introduction  Scheduling Techniques  Earned Value  Incentives/disincentives effect  Optimization of time-cost trade-off problems  Case study  Conclusion 2
  3. 3.  What is time cost trade-off?  Determining which activities to “crash” in order to produce the maximum overall job profit.  What is crashing?  Why is it important?. CASE STUDY: Renovation of residential building in downtown Montreal. 3
  4. 4. Bar Chart CPM Pert Monte Carlo Method BIM LOB LSM • Integration the project scope, time and cost using HEURISTIC METHODS 4
  5. 5. Offering contractors a monetary incentive for early project completion . Types of Incentives :  Bonus /penalty : Time based used to reward and penalize contractors for early and late project completion .  Advantage: Reduce the duration of the project  Disadvantage: Increase the cost 5
  6. 6. Indirect costs 2000 1800 increase by prolonging the duration 1600 1400  Direct costs 1200 Cost ($) increases by reducing the duration 1000 Project Indirect Cost Project Direct Cost Optimum point 800 Total Cost 600 The duration of a specific project in 400 which the least total cost happens. 200 0 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 Time (Days) 8
  7. 7. Initiation Planning Execution Monitoring Closing Generating algorithms • Optimum point can’t be found easily • Many repetitions New project • Need to define population size and duration Changing activity duration set an algorithm. Critical path changes 9
  8. 8. Ant colony optimization Ants leave a pheromone trail between the nest and the food. 1. Other ants follow the trail. 2. Too much pheromone  try a new trail 3. Different ways  Chose the shorter ones • Avoid repetition • Avoid following unnecessary paths. 10
  9. 9. Initiation Planning Execution Monitoring Fuzzy Sets • Adding weight to:  Time  Cost  Quality Closing Fitness function • 11
  10. 10.  Renovation of residential building in Montreal downtown on the corner of De la Montagne and Notre-dame .  2-storey building of 200 sq.m/floor, and 125 sq.m parking space.  Building to be delivered as a space for a restaurant including a 200 sq.m ground floor, consisting of a kitchen, dining area and two small bars. A 200 sq.m First floor divided into 100 sq.m dining area including a bar counter and a 100 sq.m terrace. 12
  11. 11.  The date when analysis was done was as of 31st of January 2013. Duration before delay = 1/1/2013 to 4/4/2013 Earned Value is implemented after activity H (Demolition) Activity A B C D E F G H I J Budgeted Cost $ $ $ $ 1,382.00 $ 4,145.90 $ 6,909.80 $ 3,454.90 $ 1,049.00 $ 410.00 $ 369.80 Actual Cost $ $ $ $ 1,210.00 $ 3,890.00 $ 6,200.00 $ 3,128.00 $ 1,000.00 $ 400.00 $ - Earned Scheduled Start Date Scheduled End Date Scheduled Duration $ 01/01/2013 02/01/2013 2 $ 03/01/2013 07/01/2013 3 $ 03/01/2013 04/01/2013 2 $ 1,382.00 08/01/2013 09/01/2013 2 $ 4,145.90 15/01/2013 23/01/2013 7 $ 6,909.80 10/01/2013 11/01/2013 2 $ 3,454.90 10/01/2013 14/01/2013 3 $ 210.00 28/01/2013 31/01/2013 4 $ 200.00 24/01/2013 25/01/2013 2 $ 24/01/2013 25/01/2013 2 As of 31st Jan 2013 Actual Start Date 01/01/2013 03/01/2013 03/01/2013 08/01/2013 15/01/2013 10/01/2013 10/01/2013 28/01/2013 24/01/2013 Not Started Actual End Date 02/01/2013 07/01/2013 04/01/2013 09/01/2013 23/01/2013 11/01/2013 14/01/2013 Not Finished Not Finished Not Finished Actual Duration 2 3 2 2 7 2 3 1 1 0 13
  12. 12.  Duration after delay = 1/1/2013 to 4/9/2013 (3 business days delay).  Original Cost = $138,169.59  Overhead = 35% of Original Cost = $48,359.36  Original Duration = 68 days working days.  Overhead per day = 48359.36 / 68 = $711.17 / working day. Planned Value Actual Cost Earned Value $ 17,721.40 $ 15,828.00 $ 16,302.60 Cost Variance $ 474.60 Schedule Variance $ (1,418.80) Cost Performance Index 1.02998484 Schedule Performance Index 0.91993861 14
  13. 13. Updated Schedule 15
  14. 14. Crashing Cost & Maximum Crashing Time 16
  15. 15. Three Cases: Case I  Penalty for delay Case II  Bonus for speed & Penalty for delay Case III  Complete crashing  test for optimization 17
  16. 16. Case I CONTRACTUAL DEADLINE = 4/4/2013, FEE OF $500/DAY OF DELAY. 18
  17. 17. Activity J n/a K 246 N 300 S 382 U 407 H 525 L 633 X 678 W 750 O 1528 T 1910 Z 2667 R Crashing Activity J has no effect Activity I cannot be crashed 180 I • • Crash Cost / Day ($) 2968 P 2999 Y 4702 M n/a Q n/a V n/a 19
  18. 18. Activity J n/a K 246 N 300 S 382 U 407 H 525 L 633 X 678 W 750 O 1528 T 1910 Z 2667 R Crashing Activity K 1 day reduces schedule by 1 day and costs $246 (<$1211.17). New critical path (add N). Activities K & N one Activity total crashing cost = 246+300=$546 per day. Crash H first 180 I • • • • Crash Cost / Day ($) 2968 P 2999 Y 4702 M n/a Q n/a V n/a 20
  19. 19. Activity J n/a K 246 N 300 S 382 U 407 H 525 L 633 X 678 W 750 O 1528 T 1910 Z 2667 R Crashing Activity H 1 day reduces schedule 3 days and costs $525.50 (<$1211.17) Activity H can no longer be crashed Activity X next to be crashed = $678.51 However, it is cheaper to crash Activities K&N at the cost of $546 180 I • • • • Crash Cost / Day ($) 2968 P 2999 Y 4702 M n/a Q n/a V n/a 21
  20. 20. Activity J n/a K 246 N 300 S 382 U 407 H 525 L 633 X 678 W 750 O 1528 T 1910 Z 2667 R 2968 P Crashing Activities K&N reduces schedule by 1 day and costs $546 (<$1211.17). This brings the contractor back to the contractual deadline of 4/4/13 180 I • • Crash Cost / Day ($) 2999 Y 4702 M n/a Q n/a V n/a 22
  21. 21. Case I Summary Total cost of crashing = $1,317.5 Days Saved = 3 Total cost of delay = Penalty + Indirect Costs= 2500+2,135.1 = $4,635.1 Crashing Cost < Cost of Delay Most of the activities are critical. 23
  22. 22. Case II BONUS OF 10% OF ORIGINAL COST [$13,816.96] IF COMPLETED IN MARCH 3/22/2013 EARLIER THAN CONTRACTUAL DEADLINE FEE OF $500/DAY OF DELAY. 24
  23. 23. Activity J n/a K 246 N 300 S 382 U 407 H 525 L 633 X 678 W 750 O 1528 T 1910 Z 2667 R Crashing Activity J has no effect Activity I cannot be crashed 180 I • • Crash Cost / Day ($) 2968 P 2999 Y 4702 M n/a Q n/a V n/a 25
  24. 24. Activity J n/a K 246 N 300 S 382 U 407 H 525 L 633 X 678 W 750 O 1528 T 1910 Z 2667 R Crashing Activity K 1 day reduces schedule by 1 day and costs $246 (<$1211.17). New critical path (add N). Activities K & N one Activity total crashing cost = 246+300=$546 per day. Crash H first 180 I • • • • Crash Cost / Day ($) 2968 P 2999 Y 4702 M n/a Q n/a V n/a 26
  25. 25. Activity J n/a K 246 N 300 S 382 U 407 H 525 L 633 X 678 W 750 O 1528 T 1910 Z 2667 R Crashing Activity H 1 day reduces schedule 3 days and costs $525.50 (<$1211.17) Activity H can no longer be crashed Activity X next to be crashed = $678.51 However, it is cheaper to crash Activities K&N at the cost of $546 180 I • • • • Crash Cost / Day ($) 2968 P 2999 Y 4702 M n/a Q n/a V n/a 27
  26. 26. Activity J n/a K 246 N 300 S 382 U 407 H 525 L 633 X 678 W 750 O 1528 T 1910 Z 2667 R 2968 P Crashing Activities K&N reduces schedule by 1 day and costs $546 (<$1211.17) K&N Can’t be crashed, crashing L is useless Fee No Longer Applicable ! 180 I • • • Crash Cost / Day ($) 2999 Y 4702 M n/a Q n/a V n/a 28
  27. 27. Activity J n/a K 246 N 300 S 382 U 407 H 525 L 633 X 678 W 750 O 1528 T 1910 Z 2667 R Crashing Activity X 1 day reduces schedule by 1 day and costs $678.51 (<$711.17). Activity Y in the critical path , Activity X is no longer crash-able. 180 I • • Crash Cost / Day ($) 2968 P 2999 Y 4702 M n/a Q n/a V n/a 29
  28. 28. Activity J 180 I n/a K 246 N 300 S 382 U 407 H 525 L 633 X 678 W 750 O 1528 T 1910 Z 2667 R • Crashing Activity W 3 days reduces the schedule by 5 days and costs $2,251.53 (>$711.17x3 working days=$2,133.51). • Crashing not justified. • Reward absorbs [13816.96] - 2251.53 + 2133.51 = $13,698.94 Crash Cost / Day ($) 2968 P 2999 Y 4702 M n/a Q n/a V n/a 30
  29. 29. Activity J n/a K 246 N 300 S 382 U 407 H 525 L 633 X 678 W 750 O 1528 T 1910 Z 2667 R Crashing Activity T 1 day reduces schedule by 1 day and costs $1910.45 (>$711.17). Activities S&U critical path. Activity X no longer crash-able. Crashing not justified. Reward absorbs [13698.4] – 1910.45 + 711.17 = $12,499.66 To continue crashing, Activities T&U are to be crashed or S&U. S&U are cheaper. 180 I • • • • • Crash Cost / Day ($) 2968 P 2999 Y 4702 M n/a Q n/a V n/a 31
  30. 30. Activity J 180 I n/a K 246 N 300 S 382 U 407 H 525 L 633 X 678 W 750 O 1528 T • Crashing Activities S&T 1 day each reduces schedule by 1 day and costs $2,293.4 (>$711.17). • Activity T no longer be crashed. Reducing Activities S&U right now will not reduce schedule. • Crashing not justified. • Reward absorbs [12499.66] – 2293.4 + 711.17 = $10,917.83 • To continue crashing Activity R. Crash Cost / Day ($) 1910 Z 2667 R 2968 P 2999 Y 4702 M n/a Q n/a V n/a 32
  31. 31. Activity J 180 I n/a K 246 N 300 S 382 U 407 H 525 L 633 X 678 W 750 O 1528 T 1910 Z • Crashing Activities R&U 3 days each reduces schedule by 5 days and costs $10,126.98 (>$711.17x3 business days). • Crashing not justified. • Reward absorbs [10917.83] – 10126.98+ 711.17 = $2,923.53 • Bonus deadline met Crash Cost / Day ($) 2667 R 2968 P 2999 Y 4702 M n/a Q n/a V n/a 33
  32. 32. Case II Summary Total cost of crashing = $18,578.37 Days Saved = 9 Total cost of delay = Penalty + Indirect Costs= 2500+6,400.53= $8,900.53 Bonus = $13,816.96 Total Benefit = 13816.96+8900.53-18578.37= $4,139.12 Crashing Cost < Cost of Delay + Bonus Risk vs. Reward 34
  33. 33. Case III CRASH ALL THE ACTIVITIES, REGARDLESS OF COST TEST FOR OPTIMIZATION 35
  34. 34. 36
  35. 35. Case III Summary Total cost of crashing = $27,770.65 Days Saved = 13 Total cost of delay = Indirect Costs= $9,245.21 Total Benefit = 9,245.21-27,770.65= -$18,525.44 Crashing Cost > Cost of Delay Most of the activities are critical. 37
  36. 36. Case III Results Day 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 Original Cost 138169.59 138169.59 138169.59 138169.59 138169.59 138169.59 138169.59 138169.59 138169.59 138169.59 138169.59 138169.59 138169.59 138169.59 138169.59 138169.59 Direct Crashing Cost Accumalative Crashing Cost 0 1051 1051 246 1297 546 1843 5999 2968.03 7842 10810.03 4636.16 3375.66 3350.98 678.51 15446.19 18821.85 22172.83 22851.34 2251.53 2667.78 25102.87 27770.65 Project Cost 138169.59 139220.59 139466.59 140012.59 146011.59 146011.59 148979.62 153615.78 153615.78 156991.44 160342.42 161020.93 163272.46 163272.46 163272.46 165940.24 Indirect Total Overhead Project Cost 51915.41 190085 51204.24 190424.83 50493.07 189959.66 49781.9 189794.49 49070.73 195082.32 48359.56 194371.15 47648.39 196628.01 46937.22 200553 46226.05 199841.83 45514.88 202506.32 44803.71 205146.13 44092.54 205113.47 43381.37 206653.83 42670.2 205942.66 41959.03 205231.49 41247.86 207188.1 38
  37. 37. Optimum Point – With Revised Schedule 39
  38. 38. • Tedious • Beneficial • ‘Prevention is better than cure’ 40
  39. 39. 41

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