Nearing completion, on time and close to budget, the Welsh assembly in Cardiff has managed to avoid the excesses of the Scottish parliament. But this welcome result belies an arduous, epic journey that involved the client ditching its original procurement route as costs started to escalate …
The members of the Welsh Assembly must be getting quietly excited about the scene unfolding before them. From their temporary home in a nearby office block, the politicians can look down on the new assembly building’s completed roof, a curvaceous and complex affair floating on slender steel columns. They can practise giving speeches in the extraordinary funnel-shaped debating chamber that will soon be cleared of scaffolding. Best of all, they can savour the knowledge that the end of a long saga is in sight. In four months, they will be able to cross a link bridge from their drab block to the glamorous new home of Welsh democracy.
If the Welsh assembly had pursued its original procurement strategy for the building, its members would probably still be staring at a hole in the ground. At first, the project bore all the hallmarks of its difficult northern cousin, the Scottish parliament. Because the assembly wanted a home fast, it chose management contracting, which has no cap on costs – not dissimilar to the construction management route used in Edinburgh. “It was not really an appropriate form of procurement,” says Ivan Harbour, the project director at Richard Rogers Partnership, which designed the building. “It was very clear there was no cost or time certainty. The brief was constantly changing and the costs were going up.” The project was halted and Rogers was sacked.
But the story finishes on a more upbeat note than the Scottish parliament did. The assembly will be able to move into its new home soon because, unlike its Scottish forebear, it pulled back from the brink just in time. The scheme was retendered early on as a design-and-build project with contractor Taylor Woodrow at the helm. How the contractor managed to deliver such a specialised, high-quality building on time and to budget for a client type not known for good housekeeping is worthy of closer examination.
Ron resigns; Rogers is sacked
Rogers won the design competition in 1998 but things swiftly started going awry. “A week later our client was found on Clapham Common,” laughs Harbour, referring to Ron Davies’ “moment of madness”, when the then Welsh secretary was mugged after an encounter with a stranger. Alun Michael succeeded Davies but soon resigned and was replaced by Rhodri Morgan, who became first minister in 2000. By this point, costs had escalated from £27m to an estimated £40m. “Morgan’s first act was to question why we were doing the project,” says Harbour. Morgan halted the scheme for a review and six months later Rogers was sacked.
Design-and-build was adopted as it provided cost and time certainty, as well as the discipline required for the assembly to come up with a final brief. “The advantage of design-and-build was that the assembly couldn’t procrastinate on design issues, as they had a builder in front of them rather than an architect,” explains Harbour. Contractor Taylor Woodrow was made preferred bidder – with Rogers as its architect.
The challenge for the assembly was to decide, then stick to, the brief. This was not as easy as it sounds because of the nature of the project. “There isn’t a building type called an assembly building with a generic cost,” says Harbour. The design had to be carefully worked out before Taylor Woodrow could submit its price.
The client took on this challenge by going back to first principles. It organised a two-day workshop for all the assembly’s key officials and the members of the Schal project management team to identify key objectives. These divided into two categories: driving factors such as cost certainty and value for money; and quality objectives that had to be delivered by the contractor. These included a good debating space, open access for members of the public, sustainability and use of indigenous materials. The brief was developed by producing data sheets that set out requirements on a room-by-room basis. “This was one of the most complex briefs for a design-and-build contract I have ever seen,” says Jerry Williams, Taylor Woodrow’s project manager for the assembly.
The contractor had just four months to put in its final price. This was only feasible because of the work that had already been done. “Conceptually, the building was fundamentally unchanged,” says Williams. However, the detailed design had to be done and
the packages had to be tendered, evaluated and value-engineered. “Doing all that in four months was pretty heavy going,” says Williams. Taylor Woodrow’s price was £41m.
Putting the voters on top
The good thing about the design is that it hasn’t been diluted to fit the budget. “They didn’t want to lose design quality,” says Williams. “A lot of the process went into ensuring that happened.” The original design concept is a single-storey concrete box for the member’s committee rooms and facilities topped by a public space. “We decided to put the electorate above the elected, which is the right way of doing things,” says Harbour. This upper area is predominantly glazed and is topped by the landmark roof. The roof design is largely unchanged, apart from tweaks to make it more economic and easier to build (see “Assembling the assembly roof”, page 50).
The building’s quality is also top-notch. “We said: do you want a cheap building now or a more expensive one that will be cheaper to run and maintain?” says Williams. “They were very clear they wanted a high-quality building that would last 100 years. This informed a lot of the decisions.”
A good example is the intensive use of Welsh slate for cladding and flooring. “Slate is cheaper over 100 years than vinyl,” says Williams. “We spent a huge amount of time getting the detailing of this right – giving the architect what they wanted and also making sure it was practical.” It also ticks the box for use of indigenous materials. Another part of the strategy to keep lifetime costs down was to choose natural ventilation and borehole cooling and heating (see “How the assembly keeps its cool”, right). Again this cost more initially but will save money in the long term, and it helps to fulfils the sustainability part of the brief.
According to Williams, there have only been about 40 variations to the contract. This compares very well with the Scottish parliament, where several thousand design changes were made during construction. “About 15 of the changes were when we went back to the client and said ‘We can make a saving if we change this’. The same number again were clarifications, so there are probably only about 10, which is pretty impressive,” says Williams. He says the building is on target to be “within pennies” of the original contract sum, as long as there aren’t any last minute changes to the design.
Unfortunately, the final bill for the building will be substantially more than the design-and-build contract sum. Piling and groundworks cost £7.5m under the original contract; the assembly is in for another £8.6m as it is responsible for the IT, broadcast and communication systems, loose furniture and art; and another £2.2m has been spent on professional fees. The grand total is £67m, including VAT. Hopefully this sum won’t be enough to take the spring out of assembly members’ steps when they make their first journey across the link bridges in four months’ time.
Project team
client National Assembly for Wales
architect Richard Rogers Partnership
structural engineer Arup
M&E engineer BDSP
steel roof structure SH Structures
concrete structure Whelan and Grant
M&E installation MJN Colston
timber soffit to roof Barrett Ceilings
wind cowl Vision
design-and-build contractor Taylor Woodrow
Assembling the assembly roof
The roof of the assembly is meant to look like it is floating above the building so it is supported by the minimum amount of structure.
“Ideally it would have been a flat roof but that would have meant a very heavy form of construction,” says Harbour. “The roof has been pushed into a form that gives it structural stability and a natural flow so it reads as one plane.”
This has been achieved by dividing the roof into six repetitive bays that flow into each other. Each bay features a central, elliptically shaped hump – the funnel-shaped structure of the debating chamber structure punches through one of these and is supported by the roof. The roof is supported in turn on 12 slender columns and cantilevers beyond the columns by up to 15 m.
“It’s quite a complex roof – rationalising it was the structural challenge,” explains Arup’s Ed Newman Sanders. His job was to create a lightweight structure with a repetitive design to make it cheaper to build. His solution was the six identical bays, with structural rigidity provided by two arches across each bay. The arches are angled at 45° to create a space at the top of the arched section. This allows the debating chamber to punch through the roof without affecting its structural integrity.
Arches need a restraint at each end to take the horizontal loads and prevent the arch from spreading. The usual solution is heavy abutments at both ends of the arch, but this would have spoiled the “floating” effect. The only alternative, connecting each end of the arch with a horizontal tie, created another problem: a tie would have intruded into the space below the arch.
The answer was to offset the ties so that they were at the edges of the bay section and didn’t protrude into it. An angled strut was used to take the horizontal loads beyond the front of the arch to the corner of each modular bay where it connected to the tie. The tie was then separated from the arch by a series of intermediate struts.
Building the roof was challenging because it only works as a structural entity once all the elements are bolted together. Taylor Woodrow specified a horizontal beam running longitudinally down the roof where it meets the columns. This stiffened the roof and allowed the loads to be carried on into the next bay so it was less prone to falling over.
“We trial-assembled the roof at our works before we went to site,” says Peter Redfern, estimating manager of steel specialist SH Structures. On site, three cranes were needed: the first to hold the arches in place; the second to position the ties at the sides; and the third for positioning the struts linking the tie and the arch. Once these were in place, the section was self-supporting. “It went together really well,” says Redfern.
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