Site Planning

By Dr. Heng Li [bshengli@polyu.edu.hk] Tel: 2766 5879

1. Learning Objectives

"An analysis of the factors affecting the decisions during contract planning stage."

2. Contract Planning and Control

This involves working out a plan of campaign or a programme for the contract as a whole and assembling the necessary data. Programme is required to promote the satisfactory organization and flow of the various building operations during the course of erection, by planning in advance the times and sequences of all operations and the requirements in labour, materials and equipment.
 

BRE Digest 91 states a well planned programme should:-

  • show the quickest and cheapest method of carrying out the work

  • ensure continuous productive work for all operatives employed and reduce unproductive time to a minimum

  • provide an assessment of the level of productivity

  • determine attendance dates and periods for all subcontractors’ work

  • provide information on material quantities and essential delivery dates, the quantity and capacity of the plant and the periods it will be on site

  • provide a simple and rapid method of measuring progress

2.1 Gantt Chart or Bar Chart

simple and easily read plan of operations

plot all site personnel against actual performances

only takes into account one of the resources, time

does not inform on the critical relationships between the various activities

 

 

 

 

 

 

 

 

 

 

 

2.2 Critical Path Diagrams

  • analyse the difference between a production problem against linear or parallel linear methods lies in the identification of the dependency between operations

  • this approach leads to interrelated networks through which certain sequences can be seen to be "critical" to the anticipated outcome

  • often convenient for the network to be set up initially using non-scaled linear arrows to represent the sequence interrelationship of activities and then plot the network aginst a linear time scale to examine the distribution of resources and to the preparation of a bar chart form of presentation.


2.3 Master Programme

  • On acceptance of the tender, contract planning commences and a working, or overall, programme is prepared.

  • This is a guide for site activities, for detailed planning, for the buying and delivery of materials, for the co-ordination of sub-contractors’ and main contractor’s work and for assessing job progress.

  • The programme shows the major operations and phasing of the job, but detailed short-term planning at regular intervals on the site is necessary to ensure the satisfactory allocation of labour and materials to each individual operation as the work proceeds.

The preparation of the overall programme consists broadly of:-

  • breaking the job down into a series of basic operations involving only one trade

  • establishing the quantities of work in each operation and the time content

  • arranging the operations in a sequence and balancing the size of gangs to give a maximum continuity of work and minimum delay

  • breaking down a large job into phases so that several operations may proceed simultaneously.



3. Planning Consideration

3.1 Site Conditions and Access

  • Site conditions will limit the type of plant that may be used.

  • Wet sites: need to use tracked machines in the case of excavators and mobile cranes, and dumpers for transport

  • Sloping sites: make the use of rail mounted cranes unsuitable or uneconomical

  • Confined sites: insufficient room for a mixer or mixing plant and may need to use truck mixed concrete

  • Site closely surrounded by tall adjoining buildings: indicate the use of a derricking jib crane rather than a horizontal jib crane in order to be able to rise and clear the buildings

  • Limitation of access

3.2 Nature of Job

Different type of structure and form, size and detailing of the building will have effect upon the way the contract is planned.

Influence the decision of equipment and materials.

3.3 Plant

General considerations: capabilities, limitations and outputs of different types of plants

Excavation plants:

The type of excvation to be carried out

The nature of the soil to be excavated

The volume of soil to be excavated

The length of haul to tip and the terrain over which the machinery has to dig and travel.

Handling:
Quantity and nature of materials to be handled

Degree of tower crane’s utilization

Avoid "Double Handling:

Sitting of hoisting plant, materials dumps and mixing plant in relation to the building and to each other

Mixing:
Quality and quantity of concrete required

Site conditions

Costs comparisons among various methods

Type of Plant:
Nature of job

Sequence of work

Method of construction

Amount of work

Cost of equipment and running cost

3.5 Design Factors

Simplicity of construction and detailing

Separation of trades

Phasing of works

Continuity of works

4. Site Organization

4.1 Site Planning

Period Planning – usually done monthly

Weekly Planning – prepare towards the end of each week progress and to plan the next week progress

Progress Control – a regular review of the progress of all operations and comparison with the programme or plan


4.2 Site Layout

Site layout is divided into Administrative Area and Construction Area.
 

Administrative Area

  • Includes stores, offices, sub-contracts’ huts, canteen and similar accommodations

  • Locate with quick access to the site area for control reasons

  • Ease of connectivity in telephone facilities for communication, electricity for power, compressed air for equipment, as well as lighting and heating facilities for office huts

  • Careful initial site planning is required to minimize to moving of administrative area during the contract period

Construction Area

  • Includes the actual site of the buildings being constructed, materials and equipment

  • Positioned to minimize the time of handling and movement

  • Areas properly identified beforehand to avoid the possibility of dumping materials in the wrong position