How Goal-Line Technology Works in Football

Arguably the most famous goal in English football history was scored at Wembley Stadium on the 30^th July 1966 when Geoff Hurst’s shot beat German goalkeeper Hans Tilkowski, thundered against the underside of the crossbar and down onto, or just over (depending on your point of view) the goal-line to give England a 3-2 lead in Extra Time.

In the spring of 2013 it was announced that the FA Premier League would adopt Hawkeye technology to provide instant decisions when the whole of the football has crossed the goal-line. Within a second of the incident taking place, a goal will be indicated upon the referee’s watch if the goal should stand. Television replays, akin to those seen in Cricket and Tennis, are then displayed to confirm the validity, or otherwise, of the goal.

The system works through the installation of a number of super fast motion cameras which shoot at a rate of 500 frames per second. They track each and every movement of the ball when it comes within range by communicating with an embedded sensor inside. Every individual image from each camera is analysed by a computer, which by using the lines on the pitch as a static point of reference can establish the exact position of the ball at any point in play.

As soon as it crosses the goal-line and the referee is notified then he can stop play if necessary immediately to signal the goal. If however a goal is claimed but hawk-eye doesn’t confirm the ball has crossed the line, the referee is able to simply wave play-on. The signal sent from Hawk-eye to the official’s watch is encrypted so that it can be free of any interference.

Critics suggest that the system could be marginalised by players obscuring the view of cameras focused on the goal-lines in the event of a goalmouth scramble; however extensive tests have proven that only a small part of the ball needs to be visible in order for an accurate decision to be made. Indeed, one of Hawk-eye’s main advantages is the computer’s ability to remove players from the generated picture when assessing whether or not the ball has crossed the line.

Alan Kirkland who works for Champion Soccer 5 a-side leagues said I can only see it being a good thing for Football, as long as it doesn’t slow down the game. The technology isn’t just amazingly accurate it is also super-fast. I don’t see it being a negative issue at all, quite the opposite.

Other elements such as fog, snow, rain and mud will also not retard the ability of Hawk-eye to work effectively and accurately due to the power of the cameras which shoot at approximately 20 times the rate than normal television cameras do.