Computer Aided Estimating

Introduction 

We have seen that estimating involves handling of an enormous amount of compilation of measurements, calculations of quantities using mostly simple arithmetic and the use of a fairly large volume of cost data, which are mostly standard. With the advent of microcomputers and their ability to rapidly accept, file, store, sort and retrieve or delete large amount of complex data with minimal error and in desired and advantageous patterns, it is realised that an estimator needs to educate himself on the use of personal computers just in the same way as electronic calculators were substituted for manual calculations a few decades back. Computers significantly reduce the time required to prepare an estimate, improve the accuracy of computations and enhance the quality of the various analyses required.  

Applications 

In the particular fields of construction estimating and cost accounting, there are already hundreds of specialist programs with more being developed every year. All of these exhibit varying degrees of quality and utility, and each has been to serve some-real or imaginary specific need of the construction estimator or cost accountant, either on an individual basis or on an industry-wide basis. Programs of most interest to construction estimators broadly fall into the categories of spreadsheets, databases, CADD and specialised  estimating packages. 

A spreadsheet is nothing more than a two-dimensional matrix which consists of vertical columns connecting with horizontal rows, to produce small boxes or "fields" into which data can be inserted. The ordinary quantity take-off paper used by estimators is a good example of a spreadsheet. Most of the examples illustrated in this unit can be easily implemented on a spreadsheet. The columns are usually identified by letters and the rows by numbers. As all columns and lines chat appear on the computer console screen at once, the program must be able to permit "scrolling" from side to side and forward and backward to permit all parts of the spreadsheet to be viewed and modified. The main advantage of the computer spreadsheet is that the program can command the CPU to manipulate data inserted into the various field cells; for example, lengths can be multiplied by widths to produce areas, and numbers of areas can be summed instantly and correctly. Reflected dimensions can be passed automatically to one or more cells, as required. If a change is made in any one cell, the results can also be automatically amended to reflect the effects of the change. Some of the popular spreadsheet packages available in the market include Microsoft Excel, Lotus 1-2-3, etc. 

Apart from measurement and summarising, there are many programs available to suit the needs of estimators involved with cost control, scheduling, purchasing payroll and other features involved in the proper management of any construction company. Filling and mailing programs are also very popular and useful for 

companies with large numbers of customers or clients, or any other extensive data base requiring storage, manipulation, and retrieval, such a labour, material, and equipment output and cost data. In the design field, there are computer programs intended to assist with the graphical aspects of design, in which the data are pictorial or graphical, as distinct from vertical or numerical. Such programs are generally known by the acronym CADD, which stands for "computer aided design and drafting". CADD programs can also be used to generate data of use to the design estimator, m the form of the perimeter lengths of walls, floor areas, building volumes, quantities  of specified elements, heating and cooling roads, and the like, which when used with other programs can generate probable costs of proposed solutions to design problems with in seconds.