Vectores

5.6.1 The past

Evolution is the process of gradual change over a long period of time involving survival of the strong and adaptable species, and extinction of those that are inherently weak or unsuited to the demands of their changing environment. Systematic improvement is the means by which the evolutionary progression can be utilized to arrive at the optimum end result.

Cost planning has evolved from crude methods of estimation to highly complex and time-consuming activities that must conform to a wide variety of procedural rules and constraints. Economic demands now make it essential to look at a number of alternative design solutions in order that the overall construction cost and/or life-cost can be minimized. The time spent on effectively examining options must be weighed against the time allowed for the task, which is perhaps a function of the level of fees paid by

the client. Education of clients in the range and benefits of cost planning activities is important.

Traditional methods of project cost management refer to cost planning activities undertaken before the advent of computer assistance. The majority of cost planning activities undertaken in the recent past could hence be classified as traditional. They have still managed to continue in popular use because the limited amount of investigation that takes place enables the process to fall within the available fee margin.

The inadequacies of traditional practice have led to the realization that the cost planning process is currently undergoing significant evolutionary change. While the mechanics of cost management are well established, the amount of time associated with their employment precludes thorough investigation. The primary role of cost planning today seems to be costing a design and then reducing or eliminating components of high cost instead of instructing the designer at an early stage in ways that would enable the project to comply with the initial budget.

Traditional methods also suffer from the inherent problem of human error. While any system that interacts with people will possess this disadvantage, the extent of its influence and ways in which it can be reduced are of interest when discussing systematic improvement. In a science that relies heavily on manipulation and sorting of cost data, areas, percentages and the like, such a component must be of significance to any procedural changes that may be made.

Guidelines are required to control the directions for efficient investigative techniques and reduce the time associated with them. Either the number of cost significant areas needs to be reduced or the pace at which these areas can be analysed increased.

Computers are an obvious means by which time-minimization can be achieved while maintaining or expanding the range of design alternatives researched. The speed and accuracy of the computer, its accessibility and in particular its versatility, are considered as prime attributes that reflect and further promote this not-so-new technology.

5.6.2 The present

Although change can come slowly to some sectors of the community, the introduction and development of computers has been a relatively rapid and widespread innovation. The present low cost of personal computers has been a major reason for this trend together with the development of computer software capable of performing many specific labour-saving activities.

Cost planning in ‘the present’ is characterized by the widespread use of computers.

Their use to date has been mostly computerized estimating and the storage and presentation of specific cost plan information in electronic databases or computer storage systems.

Although computer storage systems have a definite role and possess numerous advantages that save time and reduce errors, they do not assist the investigation of design alternatives other than by time-intensive methods based on trial and error. They certainly do not analyse or optimize the concept of the design prior to the development of a formalized scheme nor show the effects on cost of plan shape change, building height or number of storeys.

20% of the items contain 80% of the cost total cost (%)

total items (%) 100

80

20 100

5.6.3 The future

Future evolutionary trends in cost planning must involve computers. There can be little doubt that computers will become more powerful and more flexible and the amount of marketable software will continue to increase. New technology will enable greater amounts of information to be processed and allow complex tasks to be handled with more efficiency. Simultaneously the size and cost of computers will continue to decrease.

From an evolutionary point of view, the frontier for cost planning may be classified as computer guidance systems. Since only about 20% of a project’s cost can be affected after documentation has begun (see Figure 5.1), it is important that cost planning activities be concentrated on the 80% that can be manipulated during the concept stage. Computer guidance systems must be directed to this area of investigation – an area that, in the past, has been largely ignored.

Experience to date has highlighted that attempts at design optimization must be initiated at an early stage before valuable time is spent documenting inherently expensive schemes.

For practical reasons, as mentioned earlier, more detailed exploration of alternative solutions requires either that fewer areas are investigated or that we reduce the time needed to test each alternative. The second option is clearly preferred and the use of computers to carry out cost management activities means that this can be done without diminishing the depth of an investigation nor over-simplifying the effect on cost of a particular design decision.

Figure 5.1 Pareto’s law of distribution.

It is clear that current practice can be significantly improved through the utilization of computer guidance systems at all stages in the design of a project. Computer guidance systems must be able to simulate a situation in order that the problems posed will generate results that may be analysed and used in the decision-making process. They are hence prime examples of cost models. A range of cost modelling techniques can then be employed to examine the impact of a wide range of design options and their comparative merits quickly assessed.

Some of the other attributes that a computer guidance system must possess include:

䊉 the mechanics of cost generation need to be ‘transparent’ so that cost consequences can be traced through all inter-relationships

䊉 the user must be allowed to interrogate the results in great detail

䊉 the model should facilitate a dynamic decision-making process

䊉 the costing mechanism must be highly flexible and adaptable to the most innovative design solution

䊉 cost information should not interrupt the ‘flow’ of design

䊉 the model must link the user to a central database (or store of information)

䊉 the model should relate a proposed design to comparable completed projects and indicate the variability of that relationship

䊉 it should assist in solution generation

䊉 information must be presented in a consistent and familiar form

䊉 the system must be easy to use and must significantly reduce time

䊉 flexibility and practicability must be encouraged

䊉 feedback to the database is essential

䊉 previous investigations must be able to be updated

䊉 traditional methods of project cost management must be incorporated into the design of the model.

It should be noted that cost data is context dependent and inherently inaccurate as no two projects are physically identical nor are their costs. This is due to factors such as variations in site, market conditions, location and time of construction. As a result cost relationships are never completely manifest but are implicit in the construction process as a whole. It is suggested that by breaking down costs into progressively smaller components, and through continual feedback, the likelihood of significant error can be greatly reduced.

Due to the manner in which costs are generated and subsequently utilized, the computer has the potential to give results that are much more accurate than those attainable through the use of any manual method. A reassessment of existing cost planning procedures is necessary to cope with the changing building environment and its related economics. The objective is to improve investigation and accuracy while reducing time and cost.

Computer guidance systems are capable of fulfilling the identified needs.