CH 11

HORSE BLANKET

A "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

BAR CHART

A bar chart is 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..

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. If a contractor has a schedule delay, and there is no float or the float has been used up, it could cause a serious delay for the project's completion.

S CURVE

An '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.

DELAY CLAIMS

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.

EARLY START

Earliest time an activity can begin based on network calculations made by a computer (and translated into calendar dates). early start date occurs the day after the number of working days listed on the chart.

EARLY FINISH

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.

FREE FLOAT

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.

PROJECT DURATION/CRITICAL PATH

The 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.

CRITICAL PATH METHOD (CPM)

The critical path method (CPM) is a 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. In the project planning phase of this method, contractors identify necessary work elements, determine an order of operations, and prepare a network schedule to graphically illustrate the work planned. The scheduling phase involves determination of time estimates for job completion of each activity and items required for the project. Using the network schedule, most contractors use a computer program to calculate the time schedule characteristics of each item.

LATE FINISH

The 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.

LATE START

The 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.

TOTAL FLOAT

The 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.

LINE OF BALANCE

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.

PROGRAM EVALUATION & REVIEW TECHNIQUE (PERT)

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.

MATRIX

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.