Introduction Part 3

1.5 The impact of IT and CAD

Since 1987 there have been huge changes in the IT and CAD scene and practically every design office now has a computer and access to the Internet. But this has not automatically led to the production of good production information. Necessary changes to the management of the design process have not been made; in consequence CAD systems are not being used to their full potential, invariably being used as little more than electronic drawing boards.

Recent developments in IT and CAD have made it possible to build a virtual prototype of a project (i.e. a 3D model) in a computer. This enables errors, omissions and co-ordination problems in the production drawings to be identified and rectified before work starts on site, thus avoiding the expensive delays and re-working which are, at present, too common. A recent Egan 'demonstration' project at Stansted Airport on which 3D modelling was used (see Appendix D1) has shown that cost benefits of at least 10% of contract sum can be achieved. Also, significant savings in drawing costs can be expected because drawings data is shared and not re-drawn.

Figure 1.1 Lack of registration between drawings
Electronic overlay comparing two different drawings that had been approved for construction
(architect's drawing – red, structural engineer's – blue).

At present most production drawings are produced using conventional 2D CAD systems, but despite this the inadequacies of the manual methods remain (see Figures 1.1 and 1.2). However, if the disciplined procedures associated with the use of 3D modelling are used to produce 2D models a substantial part of the benefits of 3D modelling can be achieved. The adoption of such disciplines will also prepare designers for the use of 3D modelling should they so wish.

Figure 1.2 Differences in size and location of columns
Electronic overlay comparing two different drawings that had been approved for construction
(architect's drawing – red, structural engineer's – blue).

In parallel with the development of CAD systems, computerised specification systems have been developed to the point that they are now supplanting traditional word processing methods. Most recently, a computerised schedule of work system has been developed, potentially extending the benefits of co-ordinated production information to the substantial small jobs and refurbishment sector of the industry.

Although this Code mostly refers to building projects the principles apply equally to civil engineering projects. In many ways civil engineering construction has led the way, using 3D models from which to generate production drawings for highways, railways, earthworks, etc.

The principles of information sharing and common modelling processes can be adopted and extended to cover civil engineering production drawings. The principles of specification preparation can similarly be adopted for civil engineering projects.