Site layout planning can affect productivity and is crucial to project success. However, as construction is heterogeneous in the nature of its organizations, project designs, time constraints, environmental effects, etc., site layout planning for each project becomes unique. Affected by many uncertainties variables! And variations, site layout planning is a typical multi objective problem.
Problem solving requires representing the problem in a language that problem solvers can understand. However, solutions of most construction problems rely on empirical Knowledge about the site layout that can be as a site space allocation for material storage, working areas, units of accommodation, plant positions, general circulation areas, and also access and egress for deliveries and emergency services. Furthermore, conflicting objectives and the uniqueness of construction projects like bad site layout make the problems difficult to conceptualize and define.
In this report presenting, a routine task for many site staff in both precontract and postcontract stages of site layout planning of the typical multi criteria and multi objective construction problems. It is very much influenced by types of construction, density of development, and whether the site is bad or in a good layout.
Significance of Site Layout Planning
Site layout shows the relationship of the proposed site with its surroundings with respect to communication, approaches, and existing facilities. Good site layout planning assists in minimizing the traveling time and movement costs of plant, labor, and materials, activity interference during construction work, and site accidents, and ensures that work on buildings and other construction positions is not impeded by the thoughtless storage of materials on these locations. So site layout can thus either enhance or adversely affect construction productivity and progress. It is important to acquire the knowledge of the project site before setting out the site layout. The knowledge about the project site can be obtained from:
Site investigation is a process of site exploration consisting of boring, sampling and testing so as to obtain geotechnical information for a safe, practical and economical geotechnical evaluation and design. Generally it is an exploration or discovery of the ground conditions especially on untouched site.
In other words the main purpose of site investigation is to determine within practical limits, the depth, thickness, extent and compositions of each subsoil stratum, the depth and type of rock, the depth and composition of groundwater, the strength, compressibility and hydraulic characteristics of soil strata required by geotechnical engineers. Sometimes it is also known as geotechnical investigation.
Wok Procedure for SI
Steps of work involved in site investigation:
1.Desk study to collect all the relevant data and information,
2.Reconnaissance of site works,
3.Planning program after reviewing the above,
4.Ground or soil exploration includes boring, sampling and testing,
5.Laboratory testing (also field if necessary),
6.Preparation and documentation of SI report,
7.Engineering design stages,
8.Review during construction and monitoring.
Steps of Soil Exploration
Soil exploration consists of:
Boring: Refers to drilling or advancing a hole in the ground. The test would include hand auger, motorized hand boring (wash boring), deep boring (rotary drilling), and/or trial pits.
Sampling: Refers to removing soil from the hole. The samples can be classified as disturbed or undisturbed sampling. Disturbed samples are usually used for soil grain-size analysis, determination of liquid limit, specific gravity of soil as well as compaction test and California bearing ratio (CBR). The undisturbed samples are collected at least every 1.5 m and if changes occur within 1.5 m intervals, an additional sample should be taken.
Testing: Refers to determining the properties from the soil. The test can be performing either at laboratory or at field. Laboratory testing would normally be moisture content, sieve analysis, liquid limit, compaction test, CBR and so forth. Field test would include Standard Penetration Test (SPT), Cone Penetration Test (CPT) and Vane test.
Record of Soil Exploration
It is important to keep complete and accurate records of all data collected. Boring, sampling and testing are often costly. A good map giving specific locations of all boring should be available. All boring should be identified and its location documented by measurement to permanent features. And all pertinent data should be recorded in the field on a boring log sheet. Soil data obtained from a series of test boring can best be presented by preparing a geologic profile:
Arrangement of various layers of soil,
Ground water table,
Existing / proposed structures,
Soil properties data (e.g., Standard Penetration Test values).
The profile was prepared with data obtained from the boring, sampling and testing of each borehole from selected points.
Scope of site investigation works when planned by different engineers tend to be varied because there are an infinite number of conditions to be met and the process of planning also leaves many areas where individual judgment and experiences must be applied. It is also impossible to attempt to provide an exhaustive step by step guideline applicable to all possible cases. It should be realized that there is a possibility that any site investigation may leave some area unexplored or overlooked. The main risk in foundation design is the uncertainty involving in predicting soil conditions which may change with environment. The more site investigation the more it will reduce the margin of uncertainty but the time and cost requirement will be exorbitant. Therefore the extent and the cost of Site Investigation should be such that risk is at an established acceptable level to the designer and also comply to the accepted code of practice.
Decision Criteria and Site Facilities Adopted in Site Layout Planning
Although each site layout is unique, site layout planning can be resolved into a repetitive selection-evaluation process. Several analysis techniques can be used for the selection process for example, the dominant factor analysis and Parker s judgment technique, which can be used to screen out available decisions in choosing facilities, and identify key decision factors and locations for each particular facility.
All space-planning problems consist of a set of activities to be located and a space in which to locate them. Site layout planning consists of identifying the facilities needed to support construction operations, determining their size and shape, and positioning them within the boundaries of the site. So, the most temporary facilities are classified into six important categories, which are tabulated in Table 1.
Table1. General Classification of Temporary Facilities
Access road and exit
Needs vary with the type of project and the stage of the job. It will normally be linked with the plan of construction and in some cases may actually control the progress of construction. Ideally, short direct routes and one-way traffic are encouraged.
Location of plant and equipment
Choice of the major items of the plant is of real consequence on most sites. Correctly chosen and well operated and maintained equipment enables a construction project to be completed efficiently and economically.
Material storage and handling area
Areas must be set aside for the storage and handling of material. The objective here is to minimize waste and losses arising from careless handling, bad storage, or theft, and to reduce costs by obviating double handling or unnecessary movement.
Site accommodations and welfare facilities
Consideration should always be given to the possibility of ensuring that the site accommodations are kept at a suitable distance from the construction work and are in such a position to enable the site staff to conduct their duties (welfare facilities also)
This includes water supply, electricity supply, gas, telephones, and drainage the requirements of which may vary between different projects.
Position should be indicated to enable the site supervisor to arrange for the erection of the following types of workshops: 1) fitter s shops and work area; 2) joinery shop and machinery area;
3) Reinforcement and bar bending areas; and
4) Concrete mixing.
Bad site layout planning
Bad site layout is usually a multi criteria problem involving in construction site without any or less temporary facilities regarding to the type of project.
Fig1.Bad site layout
Figure1 shows one of the bad site layouts occurs daily in construction site that the Decision makers made mistake.
As you can see there are some missing temporary facilities like:
1. There is no enough access road to use. Only have two main entries that all type of vehicles can access.
2. No female toilet for any side of the site layout.
3. They don t provide any temporary office place
4. There is no storage for steel, timber and other facilities.
5. No temporary services including water supply pipes and waste storage like septic tank.
According to all that things, we can say the site layout planning is bad layout. Cause for the lake of or missing of some important facilities that leads the hall project to be fulfilled.
Site investigation product plane such as space allocations and material transportations need a lot of experience and knowledge. The planning of a site layout in practice will depend upon a number of factors such as the time and money. The need for careful site layout and site organization planning becomes more relevant as the size and complexity of the construction operation increases, and especially where spare site space is very limited.