As the world focuses on the FIFA Confederations Cup in Russia, STRI’s Head of sports surface design, Dr Richard Gibbs, examines the unique set of challenges stadium pitch design adds to the operational mix.
Stadium architecture is evolving at a rapid pace. The development and use of new and innovative cladding and roofing materials means that stadiums can be truly designed and built to reflect creative local themes and architectural flair. This, coupled with new LED sports lighting technology, an explosion of communication and social media systems, achieving optimum seating capacity and spectator comfort, plus high definition displays mean that a visit to a stadium event is marketed more as an ‘experience’ than simply watching a game of football or rugby.
However, achieving optimum seating capacity and spectator comfort can be at the expense of the turf. Low light levels, poor ventilation and cooler soil temperatures cause poorer growth in seasonally shaded parts of a pitch. Furthermore, stadiums are expensive to build and maintain, and many have to operate as fully multi-use venues for economic survival. This includes having to change the playing surface from one use to another – for example by hosting non-sporting events like concerts or grand opening ceremonies for which the turfgrass surface has no practical benefit. So, whilst the need to pay attention to television, spectator and corporate requirements on the one hand underpins a successful stadium, on the other hand the simple fact remains that there still needs to be a sustainable rectangle of turf as the focal point of the stadium bowl.
Figure 2. Comparison of uniformity of predicted photosynthetically active radiation distribution (mol/day) for a stadium with a conventional roof (l) and the Forsyth Barr Stadium (r) for the same equivalent month in spring. Note that different colour scales have been used for each stadium.
Defying the odds
Since the late 1960s the turf industry has reacted well to the challenges thrown up by increasingly complex stadium architecture and expectations for use. The expectation is that the growing environment within a stadium bowl becomes the turf consultant’s challenge to address during the design stage (will the grass grow?) and the turf manager’s challenge to manage once the stadium is operational (how do I make the grass grow better?). In other words, most stadiums are designed from an engineering, as opposed to an agronomic, perspective where the relationship between stadium architecture and its effect on turfgrass growing conditions is often one relatively minor and often somewhat simplified focus of the design.
To date, I am still aware of only one stadium where the architectural design was carried out exclusively around the need to provide a sustainable growing environment for turf – the Forsyth Barr
Stadium in Dunedin, New Zealand, a surface used successfully for the 2011 Rugby World Cup (Fig 1). This stadium was the world’s first natural turf pitch grown under a permanently fixed roof. A sustainable growing environment was achieved without the need for an extensive artificial lighting system or complex turf replacement system by:
- orientating the stadium to maximise capture of sunlight so that the pitch received a far more uniform distribution of sunlight over the pitch than a more conventionally built stadium (Fig 2)
- lowering the height of the north facing grandstand to let in more sunlight (bear in mind this is a Southern Hemisphere stadium)
- designing a 5m high ventilation slot around a large section of the pitch to allow a sensible level of airflow across the pitch
- using a bespoke rootzone designed to be far more biologically active than a conventional ‘outdoor’ rootzone
- using a stitched turf reinforcement system
- carrying out two years of local research before the stadium was built
- designing the stadium with concrete platforms for the west and east wings where temporary seating could be located, which when removed, could then be used to locate the staging requirements for non-sporting events so that the grassed surface did not require heavy duty turf protection.
Figure 3. Carpet-reinforced turf being removed off the earthquake-damaged AMI Stadium pitch in Christchurch, New Zealand (l) for reuse in a new temporary stadium in Addington (r). Despite significant damage to the surface levels, the turf was able to be harvested successfully and played on three weeks after being re-laid at Addington (source: Sports Surface Design & Management, Auckland).
Current challenges and solutions
The Forsyth Barr Stadium proved to the many turf industry experts and academics, who openly said the project was doomed to failure, that turf was sustainable under a fixed roof. But being tucked away at the bottom of the world, in a country where grass growing is almost part of the national psyche, is a very different story from the more extreme continental, tropical and arid climatic zones where ‘European’ style stadiums (ie very large stadiums with very large roofs) have been built or are being built (such as in the Middle East, Singapore and Russia). In these types of venues, it is genuinely difficult to see how a natural turf pitch can be sustained without:
a) carrying out regular turf replacement or
b) using sliding pitch technology or
c) using a temporary natural turf pitch when required
d) using a modular turf system
… plus having standard pitch ‘bolt-ons’ like undersoil heating/cooling, artificial lighting rigs, turf reinforcement and pitch vacuum and ventilation systems. Regular turf replacement has always been an option since the advent of big roll turf technology where large sections of worn or damaged turf or even entire pitches can be replaced in a matter of hours (typically 10-20m lengths of turf up to 2.4m in width, with turf rolls containing up to 50mm of rootzone depth). A key development in the success of big roll turf systems has been:
a) the development of machinery that is able to harvest and lay the turf rolls without damage
b) machinery that can remove accurately up to 50mm of damaged turf in one pass off the pitch, leaving only the minimum of re-levelling required prior to laying new turf
c) combining big roll technology with carpet-type turf reinforcement systems so that the turf can be taken back to a turf farm, renovated and re-used (Fig 3).
Sliding pitch technology is the exclusive domain of the few but one new stadium just finished using this technology is the new stadium at St Petersburg for the 2018 FIFA World Cup (Fig 4). Also, the new FFR stadium in Paris was designed with this technology until the project was shelved in late 2016 (the project was due to commence construction this year). The systems are not without their unique technological challenges – a recent inspection of the St Petersburg stadium pitch by FIFA in late 2016 showed that it had unacceptable vibration.
Figure 4 (l). The new sliding pitch at The Krestovsky Stadium, St. Petersburg, Russia, and Figure 5 (r). Prototype temporary natural turf pitch at STRI, Bingley, UK
For stadiums hosting only a handful of natural turf events per year, the most sustainable option might be a temporary natural turf pitch. This type of design involves reusable components including lightweight, modular drainage cell and shockpad, overlain with big roll technology with carpet-type turf reinforcement (Fig 5). STRI research and development has confirmed that a significantly reduced profile depth can still provide the required playing characteristics, thus making this system a genuine alternative to conventional, deeper profiles.
Palletised or modular turf systems have a checkered history. Consisting of modules typically of dimensions 1.2 by 1.2m or 2.4 by 2.4m with up to 200mm of rootzone depth, these systems were first used in the early 1990s (eg the Pontiac Silverdome which was turned into a World Cup football venue in 1994). However, the two existing proprietary systems never really took off for football use and the issue of creating seamless joints between modules was never fully solved. Both the Millennium Stadium in Cardiff and the NRG Stadium in Houston (Fig 6) have now replaced their modular systems and only last year, the international derby match between Manchester United and Manchester City on the modular pitch at the Bird’s Nest Stadium in Beijing was cancelled due to safety concerns following heavy rainfall.
The definition of what constitutes a sustainable natural turf pitch in a challenging stadium growing environment is subjective. To the purists, sustainable might mean self-sufficient with minimal energy inputs. However, this approach will be achieved only if a stadium is comprehensively and exclusively designed around the needs of the turf, a very rare occurrence indeed. It is too easy to ‘value engineer’ pitch design components out of a design to cut costs, leaving the turf manager to pick up the pieces when the stadium is handed over. The turf industry is good at finding solutions to problems of growing turf in difficult environments and these solutions need to be embraced.
Gibbs, R.J. (2011). Forsyth Barr Stadium – the undercover story. Australian Turfgrass Management 13.5: 6-12.
World Cup 2018: Russian stadium’s shaking pitch concerns FIFA http://www.bbc.com/sport/football/37867926
Manchester derby in China off after heavy rain leaves pitch unplayable http://www.bbc.com/sport/football/36881494