Fairfields was part of the design team for the All England Lawn Tennis and Club ALTC retractable roof on centre court at Wimbledon. Owing to the traditional British summer, rain would often stop play on centre court but this is now a thing of the past thanks to the construction of the retractable roof. Fairfields was awarded the contract to specify, design and commission the system controlling the movement of the roof.
The protocols for the use of the roof are governed by three basic principles, as detailed on the Wimbledon website (www.wimbledon.com)
- The Championships is an outdoor daytime event. Therefore, in good weather, the roof will only be used if it is too dark to play on without it.
- The Referee has ultimate control over use of the roof and his decision is final.
- Timings of scheduled play on Centre Court are intended to be on the same basis as the previous year. This includes the number of matches and the likely timing of those matches to be put on the court. There can be many different circumstances which will govern the opening and the closing of the roof, hence the ultimate control of the Referee.
- Hardware Design
- Software Design
- Graphical User Interface Design (GUI)
- Panel Build and Supply
- Factory Acceptance Testing (FAT)
- Site Acceptance Testing (SAT)
- Preventative Maintenance
- 24/7 Support
The overall roof system comprises of ten sections split equally into two sets of five with each section referred to as a truss. Each truss weighs 100 tonnes and is required to support the 5,200 square metre roof which weighs 3000 tonnes. The trusses are connected by means of mechanical actuators and as each section extends, a waterproof, folding, translucent fabric called Tenara is pulled across to form a weatherproof shield for the court below. The height of the roof from the ground is 16 metres.
The 212 moving elements that are required for the roof to operate need a complex control system containing some 40 control enclosures and 21 PLCs to provide synchronised operation. A complete deployment (closure) of the roof takes eight minutes with a speed of 214mm/s whilst a redundant site-wide PLC/SCADA and communication system ensures fault tolerance between all command and control stations is not exceeded. High speed data acquisition provides historical data storage to help with future maintenance. An innovative automatic system ‘pre-test’ is performed daily to defend against a component failure during roof operation. This entails the control system independently oscillating and verifying all of the moving elements to ensure the system functions faultlessly when required.
The control desk acts as the interface to the roof’s control system. This was an important requirement as the project demanded a simple user interface which would allow non-technical grounds staff to safely operate the roof. All movements can be performed using the buttons on the desk with a SCADA system providing an additional back-up.
To assist with maintenance, a high speed data acquisition database system has been incorporated. This provides an interface between the data being supplied by the truss PLC and the information available to a maintenance engineer. The data is stored by an on-board memory card within the PLC which stores the data until the truss movement has been completed. This truss movement data is then transferred to the control computer.
Once the roof is closed, it takes between 10 and 30 minutes for the court’s environment to stabilise. The Tenara fabric still allows natural light to pass through onto the grass and the airflow system removes any condensation. Although the roof is translucent, lighting is installed within the roof which comes on automatically once the roof is closed. The lights take 10 minutes to cool down prior to an opening operation, then it is another 8-10 minutes for the roof is fully open again. The roof can be safely operated in wind speeds of up to 43mph.
Prior to the 2009 championships, Wimbledon Centre Court roof was tested at a special centre court celebration in May which saw past champions playing in front of a capacity 15,000 strong crowd. The roof really came into its own at the 2009 championships and has been used at every tournament since. As well as providing cover from the rain, the roof can be partially closed in order to protect the crowds and the Royal Box from the glare of the sun.
The All England Club are now planning similar improvements for Court No. 1 with a similar retractable roof to guarantee uninterrupted play for approximately 27,000 spectators over the two courts. It is set to open for the 2019 Championships. See their ‘Master Plan‘ for more details.
The roof continues to receive regular service visits by Fairfields Engineers and we are there for Wimbledon fortnight annually to ensure the smooth operation of the roof when needed.