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PITCH PERFECT WEALTH CREATION

Prepared in time for the kick-off of the new football season, Arsenal’s innovative Emirates Stadium has already received plaudits from fans and media alike. Consulting engineer provided multi-disciplinary engineering on the project and Ian Liddell CBE FREng was in charge of the design reviews of the Emirates Stadium structures. He introduces some of the stadium’s significant features and explains how engineering was used to help deliver these.

PITCH The route from Finsbury Park When entering the arena, the design, plus imaginative create an all-seated capacity station to Arsenal Football Club’s scale and achievement of this engineering and technology. of approximately 38,000. But new Emirates Stadium in north project become clear. A view with the growing popularity of takes you past the club’s of the whole bowl, capable of football and the club’s success former Highbury ground, with its holding 60,000 fans, demonstrates THE ORIGINAL in the 1990s, it was clear that famous North Stand dominating how light and open it is. The STADIUM Arsenal needed a new home. the terraced housing around it. inward sloping roof disappears Arsenal’s stadium at Highbury Not only limiting the financial Unlike Wembley Stadium, now a and the transparent sections in north London was built in income from matches, the very visible landmark for the illuminate the seating. The focus the 1910s following the club’s stadium was squeezed into a PERFECT move from its original home in capital, Arsenal’s new home stays is entirely on the pitch where dense residential area which THE CONSTRUCTION OF THE NEW hidden until one has crossed the the action of the day is to take Woolwich. Over the years, the quickly became over-crowded footbridge and arrived at the place. To achieve this on such a terraces were exchanged for during match days, making ARSENAL EMIRATES STADIUM raised plaza that surrounds it. tight urban site required careful seating and new stands built to crowd movement difficult and

The new Emirates Stadium on its first match day, 22 July 2006, marking the departure of Arsenal's long-serving Dennis Bergkamp © Simon Warren

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PITCH PERFECT WEALTH CREATION

Other vital functions for the maintenance regime. In stadia with separate stands, stadium include crowd Factors that can be wind can enter from the corners. movement, safety and adequate controlled by the design of For Emirates Stadium, the provision of toilets – an the building are sunlight and rectangular geometry of the important part of the overall wind. In order to maximise front of the seating area visitor experience and natural light on the pitch, the interacts with the elliptical form something that has to be roof cladding is fixed to the of the perimeter to lower the considered at the design stage. underside of the steelwork and seating at the corners. With the On the plaza, spectators are the entire roof pitched down perimeter of the roof kept level, guided by colour-coded towards the turf from the this leaves gaps at the corners quadrants to lettered turnstiles constant height perimeter eaves. where wind can blow through. where their ticket is read by a This lowered the level of the The dished profile of the roof laser scanner, ensuring they only opening, thus increasing the helps deflect it on to the pitch to enter the correct zone. Upon solid angle of sky that is seen by dry the grass after dew has fallen. entering the foyer areas, fans the pitch. Illumination levels are immediately faced by food were checked by considering and drink counters that provide the geometry of the roof, the SITE CONSTRAINTS The site had a remarkable quick service, as well as an sun angles and the average number of existing buildings extensive number of toilets. amount of cloud cover. and other features that had to From the foyer, fans are directed Additional light was provided be addressed before construction towards a vomitory that by making the inner ring of the could begin. The railway lines accesses the aisle adjacent to roof translucent. This also on two sides of the site their seat. The whole system is softened shadows on the pitch restricted access for fans arriving simple to ensure the efficient and allowed more light into the and departing from the stadium handling of the large crowds seating areas. Harsh shadows and for emergency vehicles. that will regularly use it. on the pitch create problems for Two bridges were therefore Of course, cost is always an television coverage and for required to facilitate access. issue and spend on amenities footballers, to the extent that The building was designed has to be fully justified. With an some avoid running into brightly to use all of the available space anticipated project cost of sunlit areas because they are between the railway lines. approximately £390 million, the then unable to see action on Indeed, parts of the surrounding stadium is a major expenditure the opposite, dark side. podium circulation space had to for the club. This amount includes the cost of land, planning, stadium design and construction as well as relocation of local businesses and services, including building a new waste recycling centre, and regeneration HOK Sport’s design was intended to make the most of the available triangle of land © HOK Sport Architecture of the surrounding area. Outlay had to be considered with regard potentially hampering access more comfortable compared basis that when a contractor of the Premiership. To maximise to the overall business plan, for emergency vehicles. to Highbury, with row spacing was appointed the designers earnings it is necessary to get which is tied in with anticipated By the late 1990s the club typically increased from 720mm would be transferred to the the right balance of seat and income and running expenses. had located a potential site to 850mm. Seating tiers would contractor to form a design and facility prices and this affects nearby, at Ashburton Grove. This be steeper to ensure a better build partnership. layout and construction of the is a triangle of land squeezed viewing experience for all seating bowl. At Emirates THE GRASS between two railway tracks: the spectators, regardless of location Stadium – named after the club’s IS GREENER mainline out of Kings Cross in the stands. In short, the DESIGN DRIVERS Arsenal was considered by many A stadium isn’t just a place chief sponsor, the Emirates and a suburban line leading to aspiration was for a new state- to have had the best playing where fans can go and watch airline – there is a mixture of Old Street in east London. The of-the-art stadium with the best surface in the Premiership at football. It can form the nucleus general admission seating, Club site was an industrial estate, views, turf and ‘atmosphere’, Level seats with dining/bar Highbury and the club wanted containing many small predominantly meaning crowd of regeneration efforts for an to continue that tradition. area, and become the focal facilities, serviced private boxes, businesses and the Islington noise, in the Premiership. and Diamond Club seating with Ensuring good turf growth is an waste transfer station, all of The design team, with HOK point of a community through ongoing problem for any stadium hosting events and providing gourmet dining. When the which had to be relocated. Sport as architects and Buro stadium is not in use the club with a fully enclosed bowl. It employment for local people. requires water, from rain or The club’s aim was to build a Happold providing the full range and Diamond Club facilities can The stadium must make pipe, wind and sunshine in the modern stadium with modern of engineering, was appointed in be used for corporate events facilities. Sight lines would be 2000 to prepare concept enough money to enable right mix as well as the correct or entertainment. improved and seating would be designs. This was made on the Arsenal to compete at the top soil, drainage, fertilisers and Progress in June 2005. The bulk of the steelwork was in place © David Price/Arsenal FC

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oversail existing railway land in exit, this reduced the height sliding bearings at the ends of order to ensure that there was required to get fans to the the primary trusses, and by the adequate space for safe egress. upper terrace. flexibility of the tripods in the The waste transfer station The bowl structure and back- other direction. The perimeter was in the centre of the site and of-house areas are constructed truss was propped by a series an alternative had to be built primarily from concrete, but with of articulated stanchions around before it could be removed. the upper tier supported by a the perimeter, which transfer This affected the planning of steel frame. The seating steps are load down to the rear of the the whole project because the in pre-cast concrete, supported upper-tier rakers below and also stadium had to be constructed on stepped raking beams. carry the external cladding. in segments around it. Structures Vertical cores provide routes for Because of their relatively beneath the surface were also the escape stairs and vertical shallow depth, the primary affected. While a deep main service runs as well as primary trusses have an inherently low overflow sewer running across stability for the whole stadium. natural frequency. Modelling the site was left in place, a The roof structure features of the interaction between the shallower sewer had to be two 15m deep primary trusses roof and the wind-loads allowed diverted. The amount of time spanning 204m and supported the engineers to demonstrate required to achieve vacant on tripods on top of the that the roof behaviour will be possession of the whole site stadium’s end cores. These carry acceptable in all weather meant that staggered possession secondary trusses above the conditions. of the land was necessary. ends of the pitch. Tertiary trusses span from the perimeter truss to the primary and MECHANICAL AND STRUCTURE secondary trusses and carry the ELECTRICAL SYSTEMS A height limit was set for the roof sheeting on their underside. As with all modern buildings, building by Islington Council as All of these are three chord Emirates Stadium relies on its part of the planning approval. To trusses which were self-stable servicing systems. These made meet this, the bowl design had Figure 1 shows the typical section through the bowls of Emirates Stadium compared with other stadia, illustrating how improvements in seating standards and during erection which meant up a substantial proportion of hospitality facilities have had a huge impact on the size of the bowl © HOK Sport Architecture to be as compact as possible. savings in time and temporary the construction cost. Alongside The design team generated over propping. This was an important provisions for water supply, Jet flow fans were specified, fans and staff to follow the Once the bulk of the works The stadium was completed 100 bowl-sections in the quest ON TIME, consideration given the drainage and the heating of their effectiveness having been match or take part in the on- packages’ allowances were over two weeks early, having for the optimum arrangement. problems of site access and the occupied areas there were validated using computational screen betting network. While agreed the contract was WITHIN BUDGET incorporated a significant To separate vehicle access from Having agreed to the GMP and inter-relation of demolition of unusual specifications for the fluid dynamics software. this is not exceptional, with a converted to a Guaranteed number of the client’s upgraded pedestrian access, a raised a completion date, with hefty the waste transfer station, ventilation system to ensure With the roof sloping down perimeter distance of around Maximum Price (GMP). Sir finishes on budget and the external concourse (known as penalties for late delivery, hitting construction of the bowl and it can cope with the surge to the centre, pumped drainage 700m, the amount of cabling Robert McAlpine has a clear result is a stunning new the podium) was constructed deadlines was key for Sir Robert assembly of the roof steelwork. of people arriving for a game for rainwater is required. A total required to install and aim of achieving cost certainty landmark structure for football. around the building so that fans McAlpine. The philosophy of the The thermal expansion – particularly when raining of 50 pumps send water up to commission these systems before committing to a GMP The first game, the Bergkamp entered at the top of the lower project director was continually of the roof structure is because humidity will be down-pipes at the rear of the meant the work was significant and that means securing an testimonial, was played on seating tier. As well as facilitating to aim to bring the milestone accommodated by longitudinal brought in as well. Car park bowl. They have been sized to and challenging. agreed design and firm prices 22 July 2006 to a rapturous comfortable and safe entry and ventilation was also a challenge. deal with very high-strength from the package contractors. dates forward, gaining extra time welcome from fans, players storms, while overflows have For this project a great deal of if it was required. and media alike. been provided in case of power PROCUREMENT negotiation was required – for cuts, blockages or other AND CONSTRUCTION the new Waste Recycling Centre malfunctions. Electricity is The scheme design for the there were 87 works packages supplied through three stadium was presented in 2001. and for the stadium 110. transformers with diesel Sir Robert McAlpine was Many of the key packages generators as back-ups. In the appointed in February 2002 as required a substantial design event of a power failure there the main contractor for the input. For example, the is a prioritisation plan for project, which included building structural steelwork contractor discarding users, starting with the new Waste Recycling Centre. was responsible for the design electric cooking and heating. The appointment was based on of connections and preparation BIOGRAPHY – Ian Liddell CBE FREng The escape lighting, of course, a two stage process with a lump of shop drawings, as well as Ian was one of the founding partners of Buro Happold. The has to be maintained at all times. sum for Sir Robert McAlpine’s detailing the cladding fixings. practice was founded in 1976 in Bath and is now a worldwide Communications networks preliminaries and a fixed These details all require input organisation with 1,300 staff. He is now retired from the are of vital importance to the percentage for overheads and from the design team to ensure partnership and is a Visiting Professor at Cambridge University running of the stadium. Voice profit. There was also a rigorous the interfaces between packages Engineering Department and a consultant on a number of other and data links are provided to all proposed programme duration run smoothly. Clarifying the interesting and challenging projects. He was awarded a Gold areas, as well CCTV and public imposed on the project and a design input and defining Medal from the Institution of Structural Engineers and an address networks. There are also specific Sir Robert McAlpine these interfaces reduces risk International Award of Merit from the International Association TV screens in most areas to allow project team assigned. and makes for an efficient of Bridge and Structural Engineers. Ian was elected a Fellow of Emirates Stadium on 22 July, the Dennis Bergkamp testimonial © Sealand Aerial Photography construction process. The Royal Academy of Engineering in 1996.

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