New Premier League season ushers in the GLT era

After this weekend the name of footballer Branislav Ivanovic is likely to be best remembered in future pub quizzes as the answer to the question “Who was the first player in the English Premier League to be denied a goal by goal line technology?”

The Chelsea defender’s headed shot in added time at the end of the first half of his team’s opening fixture of the new season yesterday (18 August) was saved on the line at the second attempt by Hull City goalkeeper Allan McGregor. Because the indicator receiver worn by referee Jonathan Moss did not buzz and display “Goal!” play continued and the score remained 2-0 to Chelsea through to full time.

The Premier League (PL) has long been a supporter of goal line technology (GLT) and was frustrated by the unwillingness of world governing body FIFA to approve its use. FIFA president Sepp Blatter finally relented on his anti-GLT stance after England was not awarded a goal against Germany in the 2010 World Cup, paving the way for the PL to become the first national league to use the technology.

FIFA has licensed four technologies for GLT: two based on camera tracking (Hawk-Eye and GoalControl), and two on sensors and magnetic fields (GoalRef and Cairos). The governing body selected GoalControl for the recent Confederations Cup but the PL favours Hawk-Eye, which was already used for analysis and resolving disputes in cricket and tennis, among other sports. The working relationship between the PL and Hawk-Eye goes back to 2006 when the two discussed a decision system specifically for football.

There were 31 “goal line incidents” during the 2012-13 season, and once the go-ahead had been given by FIFA the PL announced in April this year that it would use Hawk-Eye from  2013-14 onwards. In the gap between the end of the old season and the beginning of the new – known as the close season – Hawk-Eye equipment was installed at the grounds of the 20 teams making up the Premier League for the new season.

Seven cameras are positioned ‘round each goal, with most installed above them in the roof of a stadium. The combination of two cameras shows the 3D position of the ball, while information from the other five gives “extra accuracy and redundancy”. The images produced identify both what is the ball and what isn’t. Cameras are able to locate the ball even if only a small portion of it is visible. The software control system is able to create a virtual image of the ball if it is obscured by players. Once the GLT has detected if the ball has crossed the goal line an alert is sent instantaneously (within one second) to a watch-like receiver worn by the referee.

The Hawk-Eye Goal Decision System (GDS) was unveiled to the football and national press on 8 August at Arsenal’s Emirates Stadium, where it had been undergoing final trials. Broadcasters, other rightsholders and their facilities companies got to see the GDS in the flesh the following day, before it was on duty for the first time at an English football match on 11 August during the Charity Shield encounter between Manchester United and Wigan Athletic, although it was not called into action.

The image of the ball in relation to the goal line is displayed on big screens in the stadium, while a version of this is also made available to broadcasters. Steve Carter, managing director of Hawk-Eye, explains that what is seen on TV is based on the shot taken by an ultra-motion camera that looks along the goal line. This makes a virtual recreation of the incident, which is combined with data fixing the actual position of the ball received from the other cameras. “The graphics are overlaid so that the virtual matches the actual,” he says.

This image is produced, Carter observes, in “typically ten to 20 seconds” and is of secondary importance to the primary function of the GDS of resolving an on-pitch situation and ensuring the progress of the game is not held up unduly. “What we’re finding is that we’re getting more efficient at producing the virtual image and with time it will get faster.”

The virtual picture is sent to OB facilities being used by broadcasters. Carter says that a typical set-up will have the GDS output fed to an EVS workstation, where it will be recorded and “be available to a director to use on air at the next break in play”.

The first use of the GDS was overshadowed by the fact that it featured in the match marking manager José Mourinho’s first game back in charge of Chelsea since his 2007 departure from the club. The notoriously temperamental coach feigned displeasure at the technological decision but then accepted it with good humour. We’ll have to see if he’s as generous if GDS gives a goal against his team.