steps in assessing the resources required in a time-limited situation

8/6/2019 Steps in assessing the resources required in a time-limited situation

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2. Steps in assessing the resources required in a time-limited situation

Time limited resource consideration. Time analysis will provide the minimum time

possible for completing the project. If this minimum is taken as the time limit, adjustment

in the timing of any activity that may affect resource requirements must be undertaken

within the float available. The steps in assessing the resource required in a time- limitedsituation are:

• Prepare a list of activities ranked in order of their earliest start dates.

• Produce a resource aggregation chart

• Produced a list of activities ranked in order of latest start dates


• Compare the resource aggregation chart

Resource aggregation charts for activities starting as early and as late as possible

Resource- limited resource consideration. The production of resource-limited

aggregation chart is similar to that of the unlimited resource aggregation, except that if

the total resource demand of an activity exceeds the specified limit then that activitymust be delayed. To produced reasonable results, and so that earlier activities are

allocated their resources first, the activities must be arranged according to a system of

priorities or decision rules.

Decision rule –is a device whereby activities are ranked in the order in which

their resource demand is added to the resource aggregation chart.



The ranking in the priority order is known as sorting, and of more common sorts

or decision rules is to sort in order of early start time. For activities with the same

early state time a second sort is required and this could be in order of total float

Resource allocation for

two resource types

Uses of computers

Where network analysis is used the possibility of using computers to do the calculation

exists. The input data required by such computers programs for each activity are start

event number, end event number, activity description, activity duration and the level of

resources required for each resource type.

In addition to the data required for each activity the available resources are also needed

if resource allocation is required.

The outputs from such programs are a time analysis, that is listing of the activities in

some order such as the earliest start date with the start and finish times and the float

calculated for each activity. The output is often also produced in bar chart form printed

by the computer. If resource analysis is done then the resource aggregation chart are

also produced.



Precedence diagrams

A. listing the activities

B. producing a logical network

• Logic. Node represents the activity and the link or arrow represent only

the logical relationship.

• Identifying the activities. Each node representing an activity can be

given a single unique number.

• Durations and time analysis.

• Relationship between activities. The major advantage offered by

precedence diagrams and the available packages are the number of

relationships that can exist between activities is more than the simple

finish-start relationship offered by arrow networks.

The main difference between precedence diagrams and activity on the

arrow system were the first one have no dummies while, no change of

reference number when additional activities are added and complex

relationship.



Line of balance

Is planning techniques for repetitive work, the principles employed are taken fromthe planning and control of manufacturing processes. The basis of the technique is to

find the required resources for each stage operation so that the following stages are not

interfered with and the target output can be achieved. The technique has been applied

in construction work mainly to house building and to a lesser extent to jetty work and in

conjunction with networks to roadwork.



Preparing a line of balance schedule

1. Preparing a logic diagram

2. Estimate the man-hours required to complete each operations.

3. Choose buffer times which will guard against the risk of interference between

operations.

4. Calculate the required output target in order to meet a given project completion

date.

5. Complete the table

6. Draw the schedule, from the information calculated

7. Examine the schedule and assess possible alternatives to bring about a more

balanced schedule which might include:

• Changing the rate output of one activity by reducing the gang size

partway through the project

• Lay-off and recall one gang

• Overlap some activities

• Or schedule every activity to work at the same rate known as

parallel scheduling and involves employing enough resources to

ensure that the rate of the output required can be achieved.

Using the schedule

The complete schedule is based on the chosen sources; therefore the rates of

construction calculated have taken account in these resources. This is different to the

network calculations, which separated logic and resource allocations.

The schedule and the start and finish dates of the various teams on each operation can

be used to monitor progress.

Updating a line of balance schedule once the project has started and if the rates of

construction prove to be different from those calculated can be difficult.



Another use of the line of balance schedule is checking material orders or deliveries. If a

deadline for ordering and/or receiving materials is marked on the schedule.

Time limited resource consideration

• Prepare a list of activities ranked in order of their earliest start dates.

• Produce a resource aggregation chart• Produced a list of activities ranked in order of latest start dates


• Compare the resource aggregation chartResource- limited resource consideration.

Decision rule –is a device whereby activities are ranked in the order in whichtheir resource demand is added to the resource aggregation chart.

Uses of computersPrecedence diagrams

A. listing the activitiesB. producing a logical network

• Logic..

• Identifying the activities.

• Durations and time analysis.

• Relationship between activities.

Line of balancePreparing a line of balance schedule

1. Preparing a logic diagram2. Estimate the man-hours required to complete each operations.3. Choose buffer times which will guard against the risk of interference betweenoperations.4. Calculate the required output target in order to meet a given project completiondate.5. Complete the table6. Draw the schedule, from the information calculated7. Examine the schedule and assess possible alternatives to bring about a morebalanced schedule which might include:

• Changing the rate output of one activity by reducing the gang size

partway through the project• Lay-off and recall one gang

• Overlap some activities

• Or schedule every activity to work at the same rate known asparallel scheduling and involves employing enough resources toensure that the rate of the output required can be achieved.

Using the schedule



The complete schedule is based on the chosen sources; therefore the rates of construction calculated have taken account in these resources. This is different to thenetwork calculations, which separated logic and resource allocations.

line-of-balance

Many types of projects contain repeated blocks of activities. Examples of these kinds of projects

include road and high-rise construction. In both of these types of projects there is a set of tasksrepeated across many work areas. Arrow and Precedence Diagramming are both able to model

these types of schedules effectively. The Line-of-Balance (also known as the Vertical Production

Method) is a graphical technique that can be used in conjunction with Arrow or PrecedenceDiagrams.

In the Line-of-Balance diagram, the x-axis represents (as in the bar chart) the timeline of the

project. The y-axis identifies the work areas that define the project. The blank chart below is thestarting point for the Line-of-Balance schedule.

As crews arrive on the project, they begin at the first work area and move through the project. In

the figure below, Activity A has a total duration of 10 weeks. Spread across each of the work areas the productivity of Activity A can be shown to be 2 weeks per floor.



Now consider the implication of an Activity B that has a productivity of one week per floor. If we try to start Activity B as soon as possible, then the start of activity B on the first floor can

occur at the end of week 2.

As we continue to add Activity B throughout the remaining work areas we can see that ActivityB starts on the second floor, at the end of week 4; on the third floor, at the end of week 6 and so

on; as shown in the diagram below.

As you look at this chart, what do you think the red dashed lines mean?



The breaks in the Activity B line, shown as red dashed lines above, are significant. This gapmeans that the crew is waiting around for Activity A to clear out before it can start. In the case of

the project above, starting work as soon as you can will result in a lost productivity of 4 crew

weeks.

The diagram below shows that you should delay starting Activity B for four weeks. If you dothat, then you will keep the crew productive for their entire stay on your project. If you were

running a real project, you might include a bit extra time in case things backup, but you would

likely not start Activity B as soon as it could start!



Use of graphical methods, such as the Line-of-Balance method result in a common

understanding of how crews follow one another through the job work areas. Such an immediate,

intuitive understanding of the project is often not possible with the output provided by commonlyused software products.

A key conclusion for you to remember regardless of what computer program you use, if youdon’t understand what it’s doing to your projects crew productivities, you will not be able to

control costs on your projects.

steps in assessing the resources required in a time-limited situation

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