Throughout the game the weather has been typical of early July – patches of sunshine and showers of rain – but the match has been protected by the court's retractable fabric roof. And the spectators know that nothing will interrupt the contest: the sky has darkened outside, but the court is lit by the artificial glow of floodlights. A drop of sweat falls from Henman's brow, he bounces the yellow ball three times, throws it into the air … and serves an ace down the centre line. "Fault!" cries the line judge. Henman protests to the umpire. The umpire is trying to announce a decision but he cannot be heard over the screaming of the crowd …
Sorry readers, we have to leave the action at that point to get back to Building magazine, which is trying to give you the news that all-weather tennis at Wimbledon came a step closer last Friday, when the All England Lawn Tennis Club lodged a planning application with the London Borough of Merton to install a retractable roof over Wimbledon's Centre Court.
If the application is successful, it will mean the end of 81 years of rain-affected matches at one of Britain's most traditional sporting events. When the heavens open, the roof will close to form a translucent cover over the players and spectators. If it is too hot, the roof can be closed and the court's air-conditioning system will ensure play can continue at perfect temperature. And when daylight begins to fade, floodlights will ensure a match can be played to a conclusion – regardless of the time.
The roof has been designed to protect profit as well as players. An estimated 1.8bn people in 131 countries watch the championships.
But the television companies that bankroll the tournament are unable to accommodate rain-forced delays into their programme schedules. By 2009, with the roof and floodlights in place, the All England Club will be able to guarantee a certain number of hours tennis to these companies. And who knows? In the future the championship's finals may be entirely floodlit affairs, with play timed to coincide with global peak television viewing figures.
Architect HOK Sport has spent three years getting the design to this stage. The first year was spent monitoring the grass in an attempt to define the best growing conditions for it (a similar exercise to the one HOK undertook at the national stadium at Wembley). "We started out by trying to define the problem, not by trying to define a design," recalls Rod Sheard, senior principal at HOK Sport.
The studies showed that grass at the southern end of court was in shadow for most of the day. The solution was to reduce the width of the fixed roof sections to create a bigger opening, thus exposing more of the grass court to sunlight. The existing roof will be removed and a new roof, with an opening of 65 × 70 m, will replace it. "The opening is huge – it's only a few metres narrower than the one at Cardiff's Millennium stadium," says Sheard. The roof will be supported independently of the existing 1922 art deco concrete structure on four columns, one in each corner of the building.
With the size of the opening defined, the architect's next task was to find a way to cover it with a retractable roof. The problem was that the fixed section of the court's roof was extremely narrow, so a sliding panel roof – like the one at Cardiff – was out of the question, as there would be nowhere to slide the panels. And they could not be stacked on top of each other without throwing shadows onto the surrounding courts. So the architect favoured a folding fabric solution.
Wimbledon couldn’t cope with Agassi spraining his ankle because the grass was sweating
Rod Sheard of HOK Sport, on creating the optimum playing environment
"We believed we could do it using a folding roof if we could only find the right material to cover it," says Sheard. Existing roofing fabrics become brittle over time and crack with repeated folding. Fortunately for HOK, though, several manufacturers were developing a fabric that would be capable of withstanding repeated folding. "There has been a breakthrough in fabric technology in the past two years," says Sheard.
Having found a solution to roofing over the stadium, the challenge then was to ensure conditions inside the enclosed space were suitable for players and spectators. One concern was that with the roof closed, condensation would form on the grass and the underside of the roof.
"We had to prove to Wimbledon that when the roof closes, the court would still be playable – the club couldn't cope with Agassi spraining his ankle because the grass was sweating," says Sheard.
Using a combination of computer simulation and 3D physical models, the team's environmental consultant, Roberts & Partners, developed an air-conditioning system capable of maintaining the court's internal environment at 24°C whatever the external conditions. The air-conditioning is critical to Wimbledon's television commitments; with the roof closed the system must be able to cope with conditions on the hottest day of the year, as well as providing warmth in an unseasonably cold snap.
Wimbledon is using the opportunity offered by the replacement roof to revamp facilities at Centre Court. Six additional rows of seating will be added to the upper tiers – raising capacity from 13,800 to 15,000 – and the quality of the seating will be improved. As part of the works, the accommodation block forming the court's east wing will be demolished and rebuilt with catering and entertainment facilities.
Work is scheduled to start in 2006. However, it will be several years before play on Centre Court can go ahead regardless of the weather. Construction has to be phased to ensure that the championships can take place each year. "We're hopeful the scheme will be ready for the 2008 championships, but it may well be 2009 before it is completed," says Sheard.