CON 2001 Construction Methods Tool #1 - Construction Scheduling Presented by Elia Twigg, P.E. (Prof. Ralph V. Locurcio, P.E.)

CVE 4070 Construction Engineering Tool #1 - Construction Scheduling Presented by Elia Twigg, P.E. (Prof. Ralph V. Locurcio, P.E.)

A little about me…

Scheduling Basics  What is scheduling?  Tool to plan, monitor and record progress  What are the benefits of scheduling?  Forces pre-planning of project  Graphical representation of project  Helps manage resources

Scheduling…  Common methods:  Bar/Gantt Charts  Network Diagrams: o CPM – Critical Path Method o PERT – Program Evaluation & Review Technique  Velocity Chart or S-Curve  Line-of-Balance Charts

Simple Bar Chart 1.Simple and easy to read 2.Does not show interdependencies or critical path

Gantt Chart 1.Simple and easy to read 2.Shows interdependencies 3.Can show critical path in a different view within MS Projects

CPM/PERT Chart

Velocity Chart or S-curve 1.Good for showing progress 2.Does not show task relationships or critical path

Line-of-Balance Chart 1.Used for production line activities 2.Shows inter- dependencies 3.Does not show critical path A A C C B B A A Between house numbers B B Activity time C C Lag time between activities

Scheduling Programs…  Microsoft Project  Easy to use  Multi-format o Network Diagram – shows CPM o Gantt Charts o Resource tracking  Excellent for small projects  Relatively inexpensive  Several other products on market

 Primavera  Used for large projects  More flexible than MS Projects  Includes resource & budget  Includes database for tracking submittals  Requires more capable computers  Generally requires trained operator Scheduling Programs…

Scheduling…  Tasks are not all consecutive  Think of the WBS (major tasks and sub-tasks)  Example – Road work and Drainage work  Project Managers need to:  Identify tasks & timing  Identify task interdependencies  Identify critical path  Identify slack/float and lag times  Chart progress & payment

Tasks & Timing…  Any single, identifiable & measurable work step in the total project  WBS  A “time consuming” task  Two conventions:  Activity on Arrow… AOA networks  Precedence diagrams (MS Projects)

Activity on Arrow… Activity Name Duration 1-3Sign Contract 3 1-2Obtain Permits 5 3-5Excavation 7 5-7Form Foundation Survey Utilities 2 2-4Layout Foundation 3 4-5Deliver Forms 1 7-8Pour Foundation 1 Sign Contract Obtain Permits Excavation Form Foundation Survey Utilities Layout Foundation Deliver Forms Pour Foundation

Precedence diagram… ActivityDuration Float Sign Contract 0 Obtain Permits 5 0 Survey Utilities 2 0 Excavation 7 2 Layout Foundation 3 0 Deliver Forms 1 2 Form Foundation 10 3 Pour Foundation 1 0 Sign contract Obtain permits Excavation Form Foundation Survey Utilities Deliver Forms Layout Foundation Pour Foundation

Task Interdependencies…  Finish-to-start (FS):  Succeeding activity (Activity B) may not begin UNTIL the preceding activity (Activity A) is completed  Most common or conventional relationship  Example…  You cannot begin constructing walls on a house until the foundation has been constructed. Finish-to-start Activity A Activity B

Task Interdependencies…  Start-to-start (SS):  Successor (Activity B) cannot start UNTIL predecessor (Activity A) begins  Very common and useful, often includes a lag time  Examples…  As soon as “Clearing & Grubbing” starts, the “Excavation” can start  Voting for the President - As soon as votes start coming in, they can begin Activity B, which is to tally the results. Start-to-start Activity A Activity B

Task Interdependencies…  Finish-to-finish (FF):  The activity must finish at the same time as a preceding activity  Infrequently used  Example…  Cooking a meal – All items you cook may have different durations, however, if you want all items to be done at one time, this would represent a finish-to-finish example. Activity A Activity B Finish-to-finish

Task Interdependencies…  Start-to-finish:  The activity may not finish until the predecessor starts  Infrequently used, not really practical to schedule  Example…  You have an exam scheduled for 11am. You determine you will cram for exam 3 hours before. You arrive in class and instructor showed up a bit late, you continue to cram until the test paper hit your desk. What determined the finish of your study time? The professor stating all study material must be put away. Start-to-finish Activity A Activity B

Critical Path  Critical Path  Longest path through network  Determines the duration of project  Shortest amount of time necessary to complete the project

Slack/Float & Lead/Lag Times…  Slack or Float - Measured within activities  The difference between the latest allowable date and earliest expected date for any given task  Lead or Lag Times - Measured between activities Finish-to-start w/lag Activity A Activity B Start-to-start w/lag Activity A Activity B Finish-to-finish w/lag Activity A Activity B Start-to-finish w/lag Activity A Activity B

Slack/Float & Lead/Lag Times…  Slack or Float - Measured within activities  Lead or Lag Times - Measured between activities

Bus Shelter Example

Scheduling Process Steps… 1.Identify key work elements (WBS) 2.Establish logical order of tasks 3.Estimate time durations for each 4.Determine precedence/dependency 5.Display in graphical/network format 6.Enter lead or lag time 7.Check network timeline 8.Add percent complete for project status 9.Convert to PERT chart 10.Explore other variations… tutorial included with software.

Identify Key Work Elements

Identify work elements…  Responsibility: prime vs. subs…  Crew or craft: carpenters, plumbers, electrical…  Use of equipment: dozer, dumps…  Materials: concrete, steel, masonry…  Subdivision of work: foundation, walls…  Location of work: site A, site B…  Breakdown in specs or for payment; i.e. CSI format  Contractor’s bid & payment elements  Other factors: like outage schedules, utilities Really depends on the contract, the controls being used, and the owner’s requirements

Estimate time durations for each Establish logical order of tasks

Determine precedence/dependency

Double Click Another way to determine precedence/dependency Lag Time

100% Complete Double Click 60% Complete

Select Network Diagram Red indicates the Critical Path

Homework #3  Using MS Project  Create a Gantt chart  Follow all instruction on Assignment  Bring to class for review & correction  Due:

Loading MS Project

Test #1 - Review

That’s all for today…BUT  STOP!!!!  Do not take the test home… turn it in before you leave