ch. 11 Flashcards
bar chart
a project scheduling method that graphically illustrates the job schedule that plots activities in a project, using horizontal bars on a chart. These horizontal bars show each activity from start to finish in relation to other activities on a job.
This widely used process allows program managers to monitor job progress, schedule subcontractors, record project advancement, check deliveries (materials and equipment), etc..
Critical Path Method
project management system that is widely used for construction time control. This process guides contractors in scheduling and time management and assists them in determining the project’s manpower, equipment, and material requirements.
CPM provides a framework for decisions in any sized project.
prime purpose to produce a coordinated project plan
CPM Network Schedule
early start early finish late start late finish Project duration/Critical Path Delay Claims
Network Schedule Floats
A float gives the amount of time an activity can be delayed without delaying the completion of the whole project. This gives a certain amount of leeway for scheduling. If needed, the activity start could be delayed or the end date of an activity could be extended without affecting the project’s completion.
early start
Early start is the earliest time an activity can begin based on network calculations made by a computer (and translated into calendar dates). If the early start of an activity shortens the project completion, the schedule may be adjusted.
On an early-start schedule, the early start date occurs the day after the number of working days listed on the chart.
Early finish
is the earliest time an activity can finish based on network calculations made by a computer (and translated into calendar dates). There are no calendar adjustments for early finish dates.
late start
date is the latest time an activity can start without delaying project completion. Total floats on a project allow a degree of flexibility in the start date on an activity.
late finish
date is the latest time an activity can finish without delaying project completion. Total floats on a project allow a degree of flexibility in the end date on an activity.
Duration/critical path
is the chain of activities that control the overall project completion. Using a precedence diagram, the project manager can identify critical activities that have identical start or finish times. These are usually differentiated by using colors, heavy lines, or double lines and must continue in one continuous path from start to finish in a scheduling diagram. Reduction of the overall project duration can only be accomplished by reducing the critical path.
Delay claims
occur when contractors make financial claims for delay damages and time extensions when it causes a delay on contract performance. These delays may be caused by the owner, architect-engineer, subcontractors, material vendors, or another prime contractor on the job.
CPM schedules can demonstrate the true effect of the stated delay, and this can assist in establishing time extensions and or compensation for the contractor. In order to do this, the project manager / contractor would need to compare the current (as-built) networks with the as-planned networks. This comparison would demonstrate any time discrepancies regarding completion times, extension of work, and required logic changes. CPM schedules can demonstrate the effect of a specific delay or multiple delays in a project.
total float (TF)
or total slack time or total slack, gives the greatest amount of time allowable to finish the activity without delaying the project completion date. Since this affects other work scheduled before and after the activity with the float, a new critical path would be developed. All of the contract participants share the total float and can use it (if it has not been exhausted) to exercise some flexibility in the project.
Free float (FF)
or free slack or free slack time, is the latest an activity can be completed without affecting other work or the completion dates of the project. These are rare and offer a degree of flexibility to those working on the activities that have a free float.
Program Evaluation and Review Technique (PERT)
is a scheduling method that was developed by the US Navy with Booz Allen Hamilton & Lockheed on the Polaris Missile/Submarine Program in late 1950s. This method was first used in building the Polaris nuclear-powered submarine and its strategic ballistic missile system.
PERT is similar to the CPM method with minor differences. With the PERT method, the accurate time table for completion and the available resources are unknown.
The line-of-balance (LOB)
method illustrates where a project has repetitive work blocks. This is represented as a single line on a graph and represents linear projects such as pipelines, electrical transmission lines, and highways. On this chart, the activities are represented as lines that run vertically, and these represent the work rate (includes all of the activities) needed to complete the project on time.
‘S’ Curve
is a track trending curve that is a graphical representation of progress over a period of time. The curve is created by vertical bars. These may also be used for historical data to visualize project trends and variations. ‘S’ Curves are also great project management tools used to monitor and forecast project performance.
Matrix
schedule is a simple way to visualize and present the work schedule for individual items or categories in a job. This type of schedule can be programmed into an Excel sheet and is an easy way to keep the work on track from day to day.
“Horse-Blanket”
schedule shows overall progress on a project through a graphical illustration that looks like a horse blanket. An example of a subway system construction project was presented in the lecture. Each task for a project is color coded. The order of tasks proceed from the bottom of the schedule to the top, with all of the tasks finishing at once. This type of schedule is good for presenting overall progress and presentations to stakeholders, NGO’s, media, neighborhood groups, etc.
general considerations
the detail planning starts immediately after the contractor has been awarded the construction contract
CPM is that its effectiveness depend on the quality of the input information and the kill and judgement with which the generated data are used.
project planning
the most time-consuming and difficult aspect of the job time management.
job logic
the sequential relationships among them are determined
reflects the order of construction operations.
used when network is first being develop
restraints
called constraints
practical limitations of one sort or must be recognized and taken into consideration.
precedence notation
depicts each activity as a rectangular box, connected to other activities with arrows
activity on node (AON)- is CPM scheduling and the computer softwares with which most projected schedule is done
arrow notation
each activity as an arrow
The precedence diagram
the key to the entire time control process
time contingency
project disruptions of activities.
can be protected by weather
not applied to unforeseen project delays caused by fires accidents equipment breakdown strikes.
project duration
as early start activities , 5 to 10 percent and add this to the overall project time requirement for the entire work.
late activity times
Backward pass- “turn around” on the value of 95 work days to find late start and late finish
least cost project shortening
only 10 to 20 percent of the activities normally prove to be critical.
significance of floats
potential scheduling leeway
resourcing scheduling
the adequate resources include materials, subcontractors, labor crews, and equipment.
A key difference between pull planning and CPM network scheduling is that
CPM network scheduling is forward-looking and based on duration and sequence, but pull planning is working from a target completion date (milestone) backward
A line-of-balance schedule would most commonly be utilized on
highway projects
A key disadvantage of utilizing a project bar chart as compared to a CPM network diagram is that
activity dependencies are not clearly shown
The historical background of PERT and CPM when both were developed in the late 1950s is that CPM is a more __________ tool as to activity durations compared to PERT which is a more __________ tool as to activity durations
deterministic, probabilistic
In CPM network scheduling, the backward-pass calculations determine
Late Start & Late Finish Times
