Unit 1CONSTRUCTION PLANNING

Basic concepts in the development of construction plans-choice of Technology and construction method-Defining work tasks-definition-precedence relationships among activities-Estimating Activity Durations-Estimating Resources requirements for work activities-coding systems.

PROJECT

A project is a unique undertaking with an established starting point and duration, using finite resources to accomplish a certain defined objective. One time effort.

Examples

Construction & renovation Architectural and engineering design Facility start-ups and relocations Equipment installation and implementation of new

technologies Information system development and implementation New product development and introduction

PROJECT LIFE CYCLE

Four phases Concept Planning Execution Transfer

As an aid to memory, these phases may be readily recalled by the letters C-D-E-F standing for: Conceive Develop Execute and Finish.

Phase I & II - the feasibility and engineering phases, are the opportunity to "build the project on paper“.

Phase III & IV - which include preparing detailed drawings and specifications, encompass the physical implementation of the project.

Submission approvals are called for at the end of each of the first two phases, and commissioning and completion approvals are typically required towards the ends of the latter two phases.

Each phase - a mini-project with its own objectives and constraints

The Level-of-Effort Curve

The LoE curve represents the number of people dedicated to the project on a full or part time basis.

The number of people involved rises steadily through the first two phases, but increases dramatically in the execution phase

At that times - difficulties of communication and coordination are experienced Consequent high levels of stress, shortages of materials and equipment,

or other unnecessary delays. Success of Execution - quality of the planning in the prior planning

phase Careful balancing act between maintaining full source ahead

to accomplish all the work Being ready to cut the throttle as soon as sufficient work is no

longer accessible to maintain the productivity of those on the project

A major lag in this decision frequently accounts for serious cost overruns

PLANNING

1. Involves breakdown of the project into definable, measurable, and identifiable tasks/activities.

2. Establishes the logical interdependences among them.

3. Answers three main questions: What is to be done? How to do it? Who does it?

PLANNING

In construction, for example, plans may exist at several levels:

corporate strategic plans, pre-tender plans, pre-contract plans, short-term construction plans, and long-term construction plans.

PLANNING

All these plans involve four main steps:

-Performing breakdown of work items involved in the project into activities.

-Identifying the proper sequence by which the activities should be executed.

- Activities representation-Estimating the resources, time, and

cost of individual activities.

PLANNING

PROJECT PLANNING STEPS

1. Define the scope of work, method statement, and sequence of work.

2. Generate the work breakdown structure (WBS) to produce a complete list of activities.

3. Develop the organization breakdown structure (OBS) and link it with work breakdown structure and identify responsibilities.

4. Determine the relationship between activities.5. Estimate activities time duration, cost

expenditure, and resource requirement.6. Develop the project network.

Determine the primary characteristics of the project Establish the project scope Establish the project priorities

Determine how best to organize the project tasks Organization by deliverable Organization by process Combination of two

Create the Work Breakdown Structure (WBS) Establish highest level, most general tasks Establish “tree structure” of lower level tasks Lowest level used to identify “work packages

STEPS TO DEFINING THE PROJECT TASKS

A family tree subdivision of effort to achieve an end objective

Developed by starting with the end objective required and successively subdividing it into manageable components in terms of size and complexity

Product or task oriented and should include all the effort necessary to achieve the end objective

WORKBREAKDOWN STRUCTURE

SAMPLE WORKBREAKDOWN STRUCTURE

Why use a WBS?

Identifies the tasks, subtasks and units of work necessary to complete the project

Identifies the relationships between tasks Increases the probability that every

requirement will be accounted Organize areas of responsibility and

authority Used to estimate project cost and

schedule Can be used to track the costs of each

element Can be used to monitor progress by

completion of tasks

WORKBREAKDOWN STRUCTURE

WBS CODING

A project code system provides the framework for project planning and control in which each work package in a WBS is given a unique code that is used in project

planning and control.

BASIC CONCEPTS IN THE DEVELOPMENT OF CONSTRUCTION PLANS

Generation of required activities, Analysis of the implications of these

activities, and Choice among the various alternative

means of performing activities. planners also face the problem of

choosing the best among numerous alternative plans.

planner must imagine the final facility as described in the plans and specifications.

construction planning is cost or expense oriented.

Within the categories of expenditure, a distinction is made

Costs incurred directly in the performance of an activity

Costs indirectly for the accomplishment of the project

borrowing expenses for project financing and overhead items – indirect costs

The proper precedences among activities are maintained and that efficient scheduling of the available resources prevails.

Scheduling - emphasize the maintenance of task precedences (resulting in critical path scheduling procedures)

Efficient use of resources over time (resulting in job shop scheduling procedures).

Finally, most complex projects require consideration of both cost and scheduling over time.

Planning, monitoring and record keeping must consider both dimensions

In these cases, the integration of schedule and budget information is major concerned.

CHOICE OF TECHNOLOGY AND CONSTRUCTION METHOD

Example a decision whether to pump or to transport

concrete in buckets will directly affect the cost and duration of tasks involved in building construction.

A decision between these alternatives -relative costs, reliabilities, and availability of equipment for the two transport methods

The exact implications - depend upon the experience and expertise of workers or the particular underground condition at a site

The cost, time and reliability impacts of the alternative approaches has to be considered

Several alternatives are made explicit in bidding competitions in which alternative designs may be proposed

Value engineering for alternative construction methods may be permitted.

In this case, potential constructors may wish to prepare plans for each alternative design using the suggested construction method

Also to prepare plans for alternative construction methods which would be proposed as part of the value engineering process.

Examples

a decision to use a particular piece of equipment for an operation immediately leads to the question of whether or not there is sufficient access space for the equipment.

Three dimensional geometric models in a computer aided design (CAD) system may be helpful in simulating space requirements for operations and for identifying any interferences.

Similarly, problems in resource availability identified during the simulation of the construction process might be effectively anticipated by providing additional resources as part of the construction plan.

DEFINING WORK TASKS

Work Tasks - Represents the necessary framework to permit scheduling of construction activities,

Estimating the resources required by the individual work tasks, and necessary precedences or required sequence among the tasks.

The terms work "tasks" or "activities“ are often used interchangeably in construction plans to refer to specific , defined items of work.

In job shop or manufacturing terminology, a project would be called a "job" and an activity called an "operation", but the sense of the terms is same.

The scheduling problem is to determine an appropriate set of activity start time, resource allocations and completion that will result in completion of the project in a timely and efficiently.

Execution of an activity requires time and resources, including manpower and equipment

The time required to perform an activity is called the duration of the activity.

The beginning and the end of activities are signposts or milestones, indicating the progress of the project

The definition of activities evolves during the preparation of the plan.

A natural hierarchy of activities with functional activities repeatedly sub-divided into more specific sub-tasks.

For example, placing of concrete on site would have sub-activities associated with placing forms, installing reinforcing steel, pouring concrete, finishing the concrete, removing forms and others.

DEFINING PRECEDENCE RELATIONSHIP

DEFINING PRECEDENCE RELATIONSHIP

ESTIMATING ACTIVITY DURATION

The estimation of activity durations is to keep historical records of particular activities and rely on the average durations from this experience in making new duration estimates.

Since the scope of activities is unlikely to be identical between different projects, unit productivity rates are typically employed for this purpose.

The duration of an activity may be estimated as Activity duration = quantity of work / number of crews x

resource output

Develop the general project definition and set of tasks

Perform a rough cost and time estimate Develop the detailed project definition,

tasks and WBS Estimate the cost and time for each

individual, lowest level element of the WBS

Roll-up (add) the cost and time for each low level WBS elements to obtain the estimates for higher level elements

Establish the project schedules Reconcile differences between the macro

and micro estimates

STEPS TO DEVELOPING THE ESTIMATES

Task Definition: The completeness of your project definition will determine if all tasks have been taken into account.

People Productivity: People do not focus on a task with 100% efficiency. The difference between “calendar time” and effort must be considered.

Project Structure: A dedicated project team will be able to focus its effort on completing the project effectively.

Padding: People may increase estimates to take into account unknown risks and this may force an unnecessary trade-off.

Culture: What is deemed acceptable behavior by the organization (e.g. padding vs. accuracy) will affect estimates.

Downtime: Equipment repairs, holidays, vacations, exam schedules can all affect the time estimate.

FACTORS AFFECTING THE ESTIMATE

Scaling: Given a cost for a previous project then an estimate for a new project can be scaled from the known cost. E.g NASA, at times, uses spacecraft weight to estimate total cost.

Ratio: Costs for subunits of the new project would be proportional to similar subunits in a previous project. For example, if it takes 1 day to build & test a particular sensor unit, then an instrument with 10 sensors would take 2 technicians, 5 days to complete.

Learning Curve: If the same task is repeated a number of times there will be a cost / time savings relative to the first time the task is done.

WBS Roll-up: Times and costs associated with the lowest level WBS work packages are estimated and then these are added or rolled-up to yield the costs for higher level units.

ESTIMATING TECHNIQUES

Estimates should be done by the person most familiar with the task

If possible obtain estimates from several people and use the variance for risk assessment

Multiple estimates should be done independently to avoid “Groupthink”

Base the estimates upon normal conditions.

Use consistent units when estimating task time.

Work package estimates should not include contingencies

Use a separate risk assessment for estimating the affect of abnormal conditions and contingencies.

GUIDELINES FOR ESTIMATES

PROJECT NETWORK DIAGRAM

A network is a graphical representation of the project activities and their relationships.

A project network is a set of arrows and nodes. Before drawing the network, ensure that the project

has a unified starting and ending point. The need for start activity arises when there is more

than one activity in the project that has no predecessors

The end activity is needed when there is more than one activity that has no successors.

Also, networks should be continuous (i.e., each activity except the first and the last has both preceding and succeeding activities)

There are two ways that are commonly used to draw a network diagram for a project: 1.Activity on Arrow (AOA) representation. 2.Activity on Node (AON) representation