CE 405 – SCHEDULING CRITICAL PATH

1. CE 405 – SCHEDULINGCRITICAL PATH In order to be an effective Scheduler/ Project Manager – and realizing that you will have too many things demanding your attention: • How will you decide which Activities you are going to focuson and intensively manage to make sure your Job gets done right?

2. CE 405 – SCHEDULINGCRITICAL PATH • Being able to calculate the Critical Path allows you to determine which Activities have to be complete when (Late Finish) in order to complete the Job within the time allocated.

3. CE 405 - SCHEDULING Scheduling software allows you to calculate the Critical Path • What is your definition of a Critical Path?

4. CE 405 - SCHEDULING Critical Path • the sequence of Activities that will have to be done chronologically – and on time – in order to complete the Project within the scheduled time.

5. CE 405 - SCHEDULING Review: What time units are you most likely to be working with when you are Scheduling a Construction Project?

6. CE 405 - SCHEDULING Time units on a Construction Project? • Whole Work Days – if it’s less than a full day, you round it up (5½ = 6) • Unless specifically noted, for the remainder of the Semester, we will be talking about full work days.

7. CE 405 - SCHEDULING If you have various subcontractors working on your Job – what two important pieces of Scheduling information are they going to be very interested in? • (not how much they are going to be paid)

8. CE 405 - SCHEDULING If you have various subcontractors working on your Job – what two important pieces of information are they going to be very interested in? • When can they Start? • When do they have to be Finished?

9. CE 405 - SCHEDULING How do you determine when work on every Activity in your Schedule is planned to Start (i.e. what calendar date)?

10. CE 405 - SCHEDULING Determine when work on every Activity is planned to Start? • You make a Forward Pass thru the Schedule

11. CE 405 - SCHEDULING What is a Forward Pass? • The process of calculating the earliesttime that each Activity on a Project can Start and Finish; thereby determining the minimumtotal duration [i.e. the longest sequence] of the Project.

12. CE 405 - SCHEDULING Review: What would be the beginning (Day 1) of your Forward Pass?

13. CE 405 - SCHEDULING Review: What would be the beginning (Day 1) of your Forward Pass? • The normal beginning for most Construction Projects is referred to as the Notice to Proceed (NTP) – when the Owner notifies the Contractor to start work.

14. CE 405 - SCHEDULING What is the difference between the following three dates? • Bid Opening Date (or Submission of Proposal Date for RFP contracts) • Contract Award Date • Notice to Proceed Date

15. CE 405 - SCHEDULING Bid/Proposal Opening Date/Time • Final Day that the Owner will accept bids/proposals • A Time (i.e. 2:00 P.M.) is usually also stipulated, after which bids/ proposals will not be accepted • After bids are publicly opened, the apparent low bidder is identified

16. CE 405 - SCHEDULING Contract Award Date – Hard Bid • After all the bids are checked for compliance with the bid submission requirements, and arithmetic checked/mistakes corrected, the contract is awarded to the low bidder that survives this review.

17. CE 405 - SCHEDULING Contract Award Date - Proposals • After all the proposals are reviewed and evaluated – and the Owner has determined which is the Best Value, the proposing companies are told which Company was selected

18. CE 405 - SCHEDULING What is the difference between a Hard Bid and a Best Value contract?

19. CE 405 - SCHEDULING What is the difference between a Hard Bid and a Best Value contract? • Hard Bid – primarily public entities awarding to lowest price • Best Value – specific criteria used to evaluate/reject proposals – award to highest evaluation point value • Don’t confuse with “pure arbitrary”

20. CE 405 - SCHEDULING Back to the original question - difference between the following three dates? • Bid Opening Date (or Submission of Proposal Date for RFP contracts) • Contract Award Date • Notice to Proceed Date?

21. CE 405 - SCHEDULING Notice to Proceed Date • The Contractor receiving the Award has to submit Performance and Payment bonds (Miller Act bonds on a Federal Government contract), as well as other “paperwork” (Minority Subcontracting Plan, etc.) before it is allowed to start work on the Job.

22. CE 405 - SCHEDULING Notice to Proceed Date • For the sake of time allocated to complete the contract (i.e. 400 days), the date of the Notice to Proceed (NTP) is the first day of the contract performance period – this is when the clock starts.

23. CE 405 – SCHEDULINGCOMBINATION CONVENTION CombinedBeginning-of-the-Day (BOTD) and End-of-the-Day (EOTD) conventions. • In order to conform Workdays into Calendar Days, Scheduling Software makes the math a little fuzzy • (Day 5 – Day 1 = 5 days), because • Day 1 starts at 8:00 A.M. and Day 5 ends at 5:00 P.M.

24. CE 405 – SCHEDULINGCOMBINATION CONVENTION BOTD + EOTD Conventions • When you are making your Forward Pass, you take the Start day, add the Activity duration (workdays), and then subtract one to get the Early Finish day.

25. Scheduling Concepts Forward Pass: • Calculates an activity’s early dates. • Early dates are the earliest times an activity can start and finish once its predecessors have been completed. • Early Start + Duration - 1 = Early Finish 11-4

26. Scheduling Concepts Forward Pass: • For the following example, we will assume that reinforcing steel work (A) takes 5 days to complete, that the concurrent formwork (B) takes 10 days to erect, and that the concrete (C) must cure for 15 days before the forms and falsework can be removed. 11-4

27. 5 1 11 25 1 10 11-4

28. CE 405 - SCHEDULING Forward Pass • After you complete the Forward Pass thru your entire Schedule, the Early Finish Day for your last Activity (normally Project Complete) will be the minimum total duration for your Project.

29. CE 405 - SCHEDULING Backward Pass • If you have completed your Forward Pass thru the network and know when each Activity should start and finish – why would you want to perform a Backward Pass thru your network?

30. CE 405 - SCHEDULING The Backward Pass calculation allows you to determine the latest that an Activity can start without delaying the finish of the Project.

31. CE 405 - SCHEDULING Backward Pass • This is just the opposite of the Forward Pass - when you are making your Backward Pass, you take the Finish day, subtract the Activity duration (workdays), and then add one to get the Late Start day.

32. Backward Pass: • Calculates an activity’s late dates. • Late dates are the latest times an activity can start and finish without delaying the end date of the project. • Late Finish - Duration + 1 = Late Start 11-5

33. 10 6 11 25 1 10 11-5

34. CE 405 - SCHEDULING Total Float • The last calculation that you will perform is the determination of the Total Float. • Total Float is the number of days that you have flexibility in starting or finishing an Activity without delaying the programmed finish date.

35. CE 405 - SCHEDULING Total Float • To determine the Total Float, you take the information from your previously performed Forward and Backward Passes, and then determine the differences between either your Early and Late Start days, or your Early and Late Finish days.

36. CE 405 - SCHEDULING Total Float (TF) is computed by subtracting either the Early Start (ES) from the Late Start (LS) or the Early Finish (EF) from the Late Finish (LF): TF = LS – ES TF = LF – EF

37. CE 405 - SCHEDULING Total Float • The Critical Path is defined as the continuoussequence of Activities that stretches the entire length of the Network where the Total Float for those Activities in that sequence is equal to zero.

38. CE 405 - SCHEDULING Total Float – Continuous Sequence • What does bifurcate mean?

39. CE 405 - SCHEDULING Total Float – Continuous Sequence • What does bifurcate mean? • “To divide into two branches” Critical Paths will occasionally bifurcate and you will then have parallel critical paths for a portion of your schedule.

40. Critical Path 5 0 0 11-7

44. Critical Path Method (CPM) Scheduling Review • CPM software uses activity durations and relationships to calculate schedule dates – you will not“fix” an Activity’s start date. • This calculation requires two passes through the activities within a project. 11-3

45. Critical Path Review • The critical path is the longest continuous path of activities through a project that determine the project completion date • A delay in one activity delays other activities and the project as a whole • Establishes the minimum total time to compete the contract. 11-3

46. Critical Path Review In order to compute the Critical Path, the two terms that you will need to understand are: • Beginning of the Day (BOTD) • End of the Day (EOTD) • All Activities Start at the BOTD and Finish at the EOTD (Activity Durations will be Whole Days.) 11-3

47. Critical Path Review In order to compute the Critical Path information for each Activity, you have to perform a Forward Pass thru the entire Schedule Network Diagram first, and then perform a Backward Pass thru the entire Schedule Network Diagram. 11-3

48. CRITICAL PATH REVIEW Critical Path Definition: The Sequence (Chain) of Activities that extends (unbroken) through the entire Project Schedule where the Total Float for all of the Activities is ZERO.

49. CRITICAL PATH SCHEDULING Critical Path Definition: It is not unusual for portions of the Schedule to have more than one Critical Path (parallel Critical Paths) – it can “split” for awhile and then “rejoin” back into a single Critical Path again.

50. CRITICAL PATH SCHEDULING Don’t try to be “smart” and submit a Schedule where all the Activities are shown as being on the Critical Path It’s notunreasonable to have as many as 20% of the Activities on the Critical Path(s)