It will be nine years in April since the Hillsborough disaster, when 95 Liverpool football fans were killed in a crush at the Sheffield Wednesday ground during an English FA Cup semi-final match.
The incident focused attention on the way in which crowd control and safety was handled in football stadia. Lord Justice Taylor's report on the inquiry into the Hillsborough disaster has meant that since the early 1990s football clubs in England, Scotland and Wales have had to redevelop their existing grounds and in some cases build completely new ones to comply with his recommendations and the subsequent changes to legislation. And elsewhere in Europe, measures had already been taken to protect spectators at major sporting events.
The initiatives have sparked a mini boom in the construction industry to refurbish old and crumbling stadia, the majority dating back to before the Second World War and some to the end of the 19th century. New construction was also commissioned where necessary, usually when the teams' homes were in urban centres and space was at a premium.
The most significant requirement of the Taylor report was that standing capacity on terracing be reduced and eventually eliminated for major football clubs and national stadia by August 1994. For all other designated grounds the timescale for compliance was extended until August 1999.
At the time, concerns were expressed that in the rush to comply, new grounds would be functional, rather than aesthetically pleasing. Simon Inglis, author of The football grounds of Europe, wrote in 1990: 'There is considerable anxiety that as clubs fall prey to the blandishments of consortia and developers, football grounds will all end up as soulless concrete boxes covered in crinkly tin - efficient, but hardly a focus for local pride and integrity.'
But in reality stadium design has had to take into account not only the change from terracing to all-seater but also the changes to the game itself. This has created some of the most innovative and spectacular structures being built today, which are certainly a source of pride to local communities and to the construction industry as a whole.
The increased popularity of football in the 1990s, the result of increased television coverage and a significant drop in crowd violence, has meant that football clubs are being run as businesses, trying to encourage more people to visit stadia, and not just for the football. Financial success requires that any new stadium development must be multi-functional, flexible and suitable for accommodating a number of different sporting and social events.
And to appeal to family groups rather than the more traditional supporter (ie young male), stadia now include club shops, restaurants and bars, corporate entertainment facilities and even hotels. Stadia are also increasingly forming parts of other wider commercial developments, especially in the case of new grounds built in out of town locations.
As stadium design has become increasingly sophisticated, foundation design has had to keep pace. In the last few years advances in steel structures have led to a variety innovations in foundation technology.
The first football stadia were little more than soil embankments built around the sides of pitches to support terracing that accommodated the increasing number of supporters as the popularity of football grew in the early part of the 20th century. Foundations were minimal, with only simple slope stability checks made. Remarkably, these embankments are still used today and not just at small clubs.
As more and more people came to see matches, grandstands were built to protect them from the elements, designs evolving from those used for cricket grounds at the time. Foundations were still straightforward, being required to take relatively low loads in compression.
The next major development came in the 1950s. Cantilever roofs meant that supporting columns could be removed, giving better views and offering an economic fillip for many clubs. But these overhanging structures meant that foundation design, while remaining simple, now had to accommodate tension loading. A further development was the appearance of the 'goal- post' roof in the 1970s, with a single beam spanning the full length of one stand, supported at either end by large columns, carrying high loads which required more substantial foundations.
And in the 1990s, roof structures have again been the major influence on foundation construction. The newest stadium roofs are supported on corner masts, which require foundations that can resist massive horizontal and vertical loads. Additionally, significant structural sway must be avoided and vertical strain must be addressed in design. These factors now mean that foundations are one of the most vital considerations for new grounds.
In the UK, by far the most popular piled foundations for new stadia are large diameter continuous flight auger piles. Developments in CFA in recent years - not least larger, more powerful rigs capable of installing piles of up to 1,200mm diameter - has meant that these piles now represent around 40% of the UK piling market. Tight control of operations is paramount and has led to increasing reliance on on-board computer systems to give quality assurance of installation. Automation has also produced cost savings, by speeding up installation and minimising concrete wastage.
Kvaerner Cementation Foundations has been involved in work on over 40 stadia, arenas and grandstands in the UK. In recent years, 75% of its projects have used CFA techniques, which has allowed many of the new stadia to be built on land previously thought to be unsuitable for development due to contamination or poor ground conditions.
The spectacular Alfred McAlpine stadium in Huddersfield is a prime example of the new attitudes towards stadium design and construction. Considered to be one of the finest stadia in Europe, it won the Royal Institute of British Architects' building of the year award in 1995.
The roof of each stand is supported by a massive steel arch beam spanning the full length of the pitch. These 'banana' trusses induce large horizontal and vertical loads to the ground via four legged finger supports at each corner, founded on cruciform configured piles. In addition to this piling, a massive bored pile retaining wall was built.
Piling work began in 1993. CFA was chosen to be the most practical way of transferring the lateral loads of up to 7,000kN at each corner, as significant penetration of the underlying weak Mercia Mudstone was needed. Three sides of the ground were completed in 1994, with the final stand due to be finished in time for next season.
Another UK ground, Bolton Wanderers' new Reebok Stadium, shows the lengths to which many clubs have had to go to comply to the Taylor report recommendations. The club's original ground in the centre of Bolton, Burnden Park, was built in 1895. The crumbling stadium needed major refurbishment to bring it up to standard so it was decided that the best solution was to build a new ground on the outskirts of the town that provided a wide variety of other facilities. The new £30M, 25,000 seater stadium at Lostock near the M61 motorway forms part of a 80ha, £150M urban regeneration project supported by the local council.
Support for the roof is provided by masts at each corner, each sitting on large pile bases each of up to 42, 750mm diameter CFA piles and inducing some 19,000kN.
Foundation movement had to be controlled and strain compatibility achieved between the corners, complicated by the variation in soil across the site. Competent coal measures are found at shallow depths in the south while in the north very soft peat occurs to depths of over 6m. Pile design at each corner had to take account of the different soil conditions for each zone and to meet the load requirements different solutions were adopted for the northern and southern corners.
More recently, Kvrner Cementation has been involved in the construction of Cardiff's Millennium Stadium. Built on the site of the original home of Welsh rugby, Cardiff Arms Park on the banks of the River Taff in the city centre, the new stadium boasts the first retractable stadium roof in Britain. This all-weather capability is just one of the features of the development thought to have been key to Wales' successful bid for the 1999 Rugby World Cup finals.
The new 72,500 seat stadium is being built at a cost of £114M, £46M of which has been provided by the Millennium Commission. Foundations must satisfy high performance specification and very heavy loads and original specification called for some 1,000 rotary bored piles penetrating deep into the underlying Mercia Mudstone to ensure low settlements. The more economical option of CFA piling was suggested as a viable alternative and proved to be so after two test piles were installed on site. Total cost savings are expected to be 30%.
In all, around 1,100 CFA piles of 600mm and 750mm diameter were installed for the stands, with between 42 and 47, 900mm diameter rotary bored piles used for each of the corner masts, three of which are now finished. Some of the rotary bored piles are raked at 1:6 to cope with the massive horizontal loads.
The move to all-seater stadia has not met with universal agreement, however. Many supporters feel that the atmosphere at many grounds has been lost and that fans are paying for the renovations through increased ticket prices. There is even a serious campaign to bring back standing at some stadia, with supporters arguing that safe standing facilities can be provided, in conjunction with proper policing and crowd control.
From 1-3 April the Concrete Society is holding Stadia 2000, a conference and exhibition on design, construction and operation of Stadia, Arenas, Grandstands and supporting facilities at the Cardiff International Arena in Wales. The conference will focus on changes in stadium development.