It's been done before but never on this scale. And it has real wow impact with potential customers. For the developer it's a way of pinpointing errors before it is too late and for the facilities manager a treasure trove of maintenance data.
If you are the main contractor on what is probably the largest town-centre retail development in the country, then spending £45 000 building a 3D replica of the scheme is probably the last thing you want to think about doing. But not Laing.

That is what it has spent on its pioneering model of Basingstoke town centre, where it is main contractor on a £110m redevelopment for Grosvenor Holdings. The job is a complex jigsaw that involves rebuilding bits of the shopping centre, without disturbing the shops that remain, to create Festival Place. A 3D replica of a town centre retail development has several uses: as a marketing tool for the developer, as a means of discovering errors before construction begins and as a potentially impressive bank of information on maintenance.

The model started life in Laing’s offices in Hemel Hempstead where a trio of 3D technicians headed by senior CAD consultant Mervyn Richards are based. The team has already put together a model of the £6.5m KLM building at Stansted Airport for BAA, which was completed last June and saved about £600 000 by finding inaccuracies in the plans before the scheme got to site. An example of the sort of errors it spotted was the pre-cast concrete stair slabs 10 mm too long to fit with the handrail. The challenge, however, was to try the model out on a big scheme. “People were always saying to us: ‘You only use this 3D thing on small projects’, so we thought: right then, we’ll try it on something bigger,” says Richards.

To build what is effectively an intelligent prototype of the 11.5 ha town-centre development is an astonishingly simple, but time-consuming, process. It has taken two technicians three months to create the project within a project. The 3D modelling technician traces, for example, a door from the 2D CAD drawings supplied by the architects, clicks on his mouse, and the 3D version of the object appears on screen in seconds. The information, down to the finer details on the doors, louvres and window frames, is held on about 100 models, which add up to a 160 MB file. The platform used is AutoCAD 2000.

If you fancy a stroll through the virtual project, all it takes is a click of the mouse to activate another crucial piece of software. Navis Roamer compresses the 160 MB files into a 12-14 MB file, which is much more PC-friendly, allowing the user to walk through the scheme. “We couldn’t get the information on a single model onto the PC otherwise,” explains Richards.

Indispensable marketing tool

On the Basingstoke site, the project model has been greeted with enthusiasm by both Paul Ashford, Laing’s construction director, and Lawrence Chadwick, associate director at Grosvenor Estates.

As soon as Chadwick clapped eyes on the model, he was smitten, and demanded a copy for his laptop. As a marketing tool, it is proving to be indispensable. Chadwick can take it to meetings with the likes of Debenhams, which can take its staff on a trip around the scheme and answer any questions they may have. Chadwick is also finding the tool a way to lure potential tenants into signing for unlet units. “It is so much easier to describe what is going on,” says Chadwick.

Laing’s Ashford has a giant Plasma screen in his site office on which he can call up the model. On such a complicated project, the sequence of the construction programme is vital. The cut-throughs and elevations of different sectors allow Ashford to make informed judgements. On one occasion, Ashford took a routine “walk” around the model and found a problem with the image. “I homed in on that big, dark shade and found it was a brick stair tower,” he says. He realised that the tower had to be completed before a glass rotunda on the British Homes Stores building was built, otherwise there would have been no room to put up scaffolding without doing some damage to the glass of the rotunda.

It may sound mind-bending to walk through a virtual site, but both Ashford and Chadwick have found the model reasonably easy to use. However, they both agree that it takes time to get to grips with what it can do. “It is easy to use if you open your mind,” says Ashford. “I made sure my diary allowed a few hours here and there, but once you understand what it does, it is simple.” Ashford and Chadwick have only been using the model on one project, but both feel that its potential for getting across the impact of a building this size is immense. Chadwick is determined to use models for other Grosvenor projects right from the planning stage. He can then take local town planners and councillors on a trip through a proposed building, instead of relying on a cardboard mock-up and some incomprehensible plans. “For the next presentation, we have a tool we know works and that we are conversant with,” says Ashford. “The PowerPoint slide is prehistoric.”

Finding inaccuracies in plans is the bane of a contractor’s life. And that is one of the areas where Laing hopes to find about 10% savings. The piling close-up shows the potential for identifying errors in the drawing’s dimensions.

In Mervyn Richards’ department, the 3D technicians look for details on the model that show up areas where, for example, a door does not fit the hole made for it, or ductwork misses its connection to the wall. Once an inaccuracy is identified, the drawings are sent back to the designer to check. Laing certainly thinks its 45 000 has been well spent.