Planning: Process of choosing the method and order of work
Scheduling: Process of determining the interrelationship of associated timings of operations.
Steps in Construction Scheduling
Splitting of the project into work activities
Determining logic relationships/interrelationships between activities.
Construction of Network Diagrams.
Assigning durations to work activities.
CPM Calculations resulting in start times, finish times and float calculations of activities.
Marking of critical Path
Construction of Bar Charts / Time phased diagrams.
An element of work performed during the course of a project. Or
An amount of work that can be identified so that we know what it involves and can recognize, when it starts and finishes.
An activity normally has an expected duration, an expected cost, and expected resource requirements
Any schematic display of the logical relationship of project activities.
Always drawn from left to right to reflect project chronology.
Usually a combination of arrows and nodes.
Mainly of two types:
Node Diagram / Precedence Diagram
Activities shown by Arrows. Relationship between activities shown by nodes / events.
Length of arrows does not obey any scale.
Numbering of nodes / events.
Activity duration is forecasted by any of the several means, including:
Check Past Records.
Check Standards and / or cost guides, if available.
Ask the workers, who will do it
make an educated guess
Any time units may be allotted to activity durations like days, hours, weeks, months, shifts, etc.
In CPM, a single duration is forecasted for an activity.
In PERT (Program Evaluation & Review Techniques), 3 durations are forecasted for an activity and mean taken by weighted average method. Then, Project’s Duration or any Event Completion Time is calculated by probability distribution.
Calculates the following for each activity
EST = Earliest Starting Time
EFT = Earliest Finishing Time
LST = Latest Starting Time
LFT = Latest Finishing Time
TF = Total Float
FF = Free Float
Total Float is Maximum time for which an activity can be delayed without delaying the project.
Free Float is maximum time for which an activity cane be delayed without delaying the start of proceeding activity.
Total Float = Free Float + Interfering Float
The path (or paths) in the network diagram, from start to finish, on which all the activities have zero total and free floats, is called Critical Path.
It is the longest path (or paths) from start to finish in a net work diagram.
It gives minimum normal time to complete a project.
It is usually marked by double lined arrows in a network diagram.
SINGLE SPAN BRIDGE PROJECT
Activities shown by Nodes, relationship between Activities shown by arrows or links.
Easier to construct.
Generally no need of dummies. Instead dummies used only to give single start or finish.
CPM Calculations similar to Arrow diagrams.
Gives Pictorial Representation of Activities.
Activities begin at EST and show their EFT, FF, TF, Durations, etc.
Arrows at the relative ends to show dependency.
Status Line Concept
Unable to show complete interdependency between Activities.
Time-scaled Network Diagrams show complete interdependency between Activities.