4E1 Project Management

1. 4E1 Project Management Network Representation and Critical Path Analysis - Part 1

2. Key Concepts • Networks • Building networks, possible problems, scheduling objectives • Critical path (analysis) • Calculating the critical path, possible complications, handling constraints • Project planning software • Project Evaluation and Review Technique (PERT) • Using simulation with PERT • Project plan

3. Structure of Session • Developing a project schedule to build a garage • Starting point: specification and info on resources • From this you will create: • a WBS • a task list • an arrow diagram network of the project • a precedence diagram of the project (homework) • We will then examine the concept of critical path • You will determine the critical path through the network • We will look briefly at PERT • We will conclude with a summary of the plan • We will consider some of the software tools available to help

4. 8m x 5m garage Concrete base Wooden trussed & sheeted roof Double wooden doors No windows Side fascia boards Side gutter system which drains to a soakaway trench containing a drainage pipe Doors and trusses will need to be made up All exterior woodwork and doors to be painted Brick walls; no plastering required Reinforced steel joist (RSJ) required for the door You have all materials including bricks, wood, sand, cement, aggregate, ready-made guttering and grills plus nails, screws etc. and a full set of tools (mixer, spades, saws, etc.) and labour Assume that drainage is into an open pond and needs no connection to a main system Specification

5. Exercise 1 • Draw up a work breakdown structure • From this, draw up a task list

6. Ridge beam Truss Beams Sheeted roof RSJ lintel Door Frame Fascia Boards Wooden Double Doors Gutter Drain (under ground) Brick walls Building a Garage

7. Extract from Possible WBS 1. Base 2. Drainage 3. Walls 4. Doors 4.1 Make door frame 4.1.1 Cut frame timbers 4.1.2 Prime frame timbers 4.1.3 Assemble frame 4.1.4 Paint frame 4.2 Make doors 4.2.1 Cut door timbers 4.2.2 Prime door timbers 4.2.3 Assemble doors 4.2.4 Fit hinges 4.2.5 Hang doors 4.2.6 Paint doors 4.2.7 Fit bolt 5. Roofing…

8. We will first consider information-on-arrow representation Information-on-arrow networks can be used to represent various problems e.g.: Shortest route Flow capacity Projects The following terminology is used in networks: Nodes Sources/starts Sinks/ends Links/arcs Directed and undirected Loops Circuits Paths Some Network Concepts

9. Example: Shortest Route Problem 5 100 20 10 80 60 60 2 70 30 20 40 70 6 90 20 110 1 120 12 9 Start 3 50 40 80 Finish 50 90 7 30 70 80 90 11 4 70 110 60 100 8 Find the shortest route through this network where numbers are distances in kilometers – have fun!

10. Arrows/links represent a task or activity and its duration - hence “Activity on Arrow” (AOA) conventionally run left-right One and only one starting node completion node link between each pair of nodes (why?) At least one path from start to completion No circuits or loops May be multiple paths from start to completion special activities, and thus links, with zero duration Project Networks Project networks have some specific characteristics:

11. Exercise 2: Draw This Network No. Task ID Task Duration Predecessors Resources 1 START Project start 0 2 G0102 Dig foundation 8 1 Labourer 3 G0103 Make, prime door frame 6 1 Skilled 4 G0104 Dig soakaway, trench 2 1 Labourer 5 G0107 Make doors 1 1 Skilled 6 G0110 Cut roof timbers 1 1 Skilled 7 G0205 Concrete foundations 2 2 Labourer 8 G0305 Position door frame 1 3 Skilled 9 G0411 Lay underground pipe 1 4 Labourer, Skilled 10 G0508 Build main brick walls 10 7, 8 Skilled, Labourer 11 G0509 Lay concrete base 2 7 Labourer 12 G0713 Prime the doors 1 5 Skilled 13 G0810 Fit RSJ lintel 1 10 Skilled, Labourer 14 G0913 Lay floor screed 1 11 Skilled 15 G1012 Fit roof timbers 2 6, 13 Skilled 16 G1016 Case lintel, parapets 2 13 Skilled, Labourer 17 G1115 Fill draining trench 1 9 Labourer 18 G1214 Fit fascia boards 1 15 Skilled 19 G1216 Fit roof sheets 1 15 Skilled 20 G1317 Hang doors 1 10, 12, 14 Skilled, Labourer 21 G1417 Fit gutters and pipes 1 9, 18 Skilled 22 G1518 Concrete over trench 1 17 Labourer 23 G1618 Seal the roof 2 16, 19 Skilled 24 G1718 Paint all woodwork 3 20, 21 Skilled 25 FINISH Finish project 0 22, 23, 24

12. Prime doors 1 F I N I S H M B Hang Doors 1 Lay floor screed 1 Make doors 1 Build walls 10 Fit RSJ 1 Position d/frame 1 L F I Q C Paint Wood 3 Make& Prime door frame 6 S Case lintel and parapets 2 Fit gutters and pipes 1 Dig foundation 8 Concrete fdns2 Concrete base 2 J G D A Concrete over trench 1 Seal Roof 2 S T A R T Dig trench 2 K Fill Trench 1 P R Lay under- ground pipe 1 H E Fit fascia boards 1 Fit roof sheets 1 Cut roof Timbers 1 Fit roof timbers 2 O N Solution…

13. Slack Typical task has earliest start and latest completion times Slack = LC - ES Critical path If all tasks on a path from start to completion have zero slack, the path is on the critical path Free float Activities that can start late or finish early have free float Activities on the critical path have no free float Interfering float An activity that can only be delayed in its float at the expense of some other activity’s float has an interfering float Other types of float exist Sub-critical activities Activities with a small free float are sub-critical activities Project Network Features

14. May be > 1 objective e.g. To minimise: Total project time Total project cost Cost for a given time Time for a given cost Idle resources CPA methods used as: planning tools control tools Many software packages can calculate the path May be > 1 critical path Critical Path Network Objectives

15. To find the critical path three steps are required Requires care and thought Easy to make a mistake 1. Forward pass Traverse network from start, calculating earliest possible completion time of each task. This will give you a total time for the project. 2.Backward pass Working backwards from end, calculate latest completion time needed to complete each activity’s preceding task. 3. Identify critical path Nodes where the forward earliest completion time equals the backward latest completion lie on the critical path. Also single pass method Critical Path Method (CPM)

16. e.g. Task (4,6). Duration 5 days 4 2 3 5 2 0 Start 7 0 2 3 6 5 6 3 Finish 2 2 1 3 Example 1: Simple Project Network What is the critical path through this network?

17. Step 1: Forward Pass 6 4 3 0 2 3 5 2 0 Start 7 19 0 13 2 3 6 5 6 3 Finish 2 2 1 3 6 2

18. Step 2: Backward Pass 6 6 3 0 4 3 0 2 19 3 5 2 0 Start 13 7 19 0 13 2 3 6 5 6 3 Finish 2 2 1 3 6 4 6 2

19. Step 3: Critical Path 6 6 Start 0 3 4 3 0 2 19 3 5 2 0 Start 13 7 19 0 13 2 3 6 5 6 3 Finish 2 2 1 3 6 4 6 2

20. Exercise 3: Given the Following… 9 4 3 e 4 0 3 d3 0 k b d2 4 3 7 0 1 2 2 10 1 3 6 7 11 2 8 j f a m l c d1 9 8 h 1 i g 5 d 5 Find the critical path through this network

21. Exercise 3:Forward Pass 23 10 9 4 3 4 0 3 0 16 24 0 3 10 7 4 3 0 1 2 2 10 1 3 6 7 11 2 8 9 8 10 5 1 20 23 5 8

22. Exercise 3: Backward Pass 23 13 23 10 9 4 3 24 4 0 16 0 3 3 14 0 16 24 0 3 10 7 4 3 0 1 2 2 10 1 3 6 7 11 2 8 13 20 23 9 8 10 5 1 20 23 5 8 8

23. 23 13 23 10 9 4 3 24 4 0 16 0 3 3 14 0 24 16 0 3 10 7 4 3 0 1 2 2 10 1 3 6 7 11 2 8 13 20 23 9 8 10 5 1 20 23 5 8 8 Exercise 3: Critical Path

24. Exercise 4 • Find the critical path for the garage project • Ignore labour constraints and non-working days 24 23 20 Prime doors 1 1 F I N I S H M B Hang Doors 1 20 Lay floor screed 1 10 25 9 21 20 10 6 25 Make doors 1 21 Build walls 10 Fit RSJ 1 Position d/frame 1 L F I Q C 0 Paint Wood 3 Make& Prime door frame 6 0 S Case lintel and parapets 2 23 Fit gutters and pipes 1 Dig foundation 8 Concrete fdns2 Concrete base 2 28 J G D A 12 Concrete over trench 1 28 8 10 Seal Roof 2 S T A R T Dig trench 2 K 8 27 10 Fill Trench 1 24 4 P 26 R Lay under- ground pipe 1 H 24 E 24 Fit fascia boards 1 24 Fit roof sheets 1 21 23 3 2 21 Cut roof Timbers 1 Fit roof timbers 2 O N 23 23