The Goal Line Technology - No Mistakes in 2014 World Cup

What is goal-line technology? 

Official goal-line technology ball

As was requested by the IFAB as a condition for its implementation goal-line technology is straightforward: it is a technical means of instantly determining whether or not the whole of the ball has crossed the goal-line, not more and not less. 

referee’s watch with goal indication

No interference with the game

The IFAB required that goal-line technology was not to interfere with the game. As a consequence the requirements were set up determining that only the match officials are to receive a signal to indicated whether or not the ball has crossed the line. The information is transmitted within one second which ensures immediate response from the referee. Due to this design there are no stoppages or other forms of interference in the game.

Support for the match officials

The match officials are the only ones to receive the signal on their watches. Unless there is a conscious choice by the competition organiser to show a reply, the information is only available to the referee and helps in challenging situations.

How does it assist the referee?

The International Football Association Board made the introduction of goal-line technology conditional of the assistance it can provide to the match officials. They receive the automatic goal signal within one second to their watch which helps them make the correct call despite the following challenges.

Human eye

One of the challenges for referees is that the human eye can handle only approximately 16 images per second, which means the ball needs to be behind the line for at least 60 milliseconds.

However, in some cases the ball is only behind the line for a few milliseconds before a player kicks it back or it rebounds back into the field of play, with the result that the human eye cannot see whether the ball has crossed the line. The ball can only be detected by the human eye at a speed of 12km/h or less, whereas nowadays players are able to shoot at a speed of over 120km/h (cf. “The hardest recorded shot in football – ever”, 14 February 2007, The Guardian).

Vantage point

Another challenge is the vantage point. When viewed from certain angles, it is easy to misjudge the ball’s position. Cameras placed at different angles can mislead viewers when showing images “proving” whether or not the ball has crossed the line, which is why only technology dedicated to evaluating such incidents can support the referee in the decision-making process and contribute to a fair game.

One situation, different perceptions

Same ball, different angle. What is your verdict: goal or no goal?

Based on this image, would you give a goal?

Same situation, again. It is clear that the ball has not completely crossed the line.

Thoroughly tested

To ensure the highest possible quality in the field of goal-line technology, any approved system must successfully pass a series of system tests as well as an installation test before it is approved for use in official matches:

System Test

Consisting of field, laboratory, training and live tests, the purpose of these system tests is to give football leagues, clubs, associations and confederations intending to install goal-line technology the total assurance that the system complies with the Laws of the Game. These tests are conducted under the expert eye of the independent FIFA-accredited test institute EMPA, based in St. Gallen, Switzerland.
While the purpose of the laboratory tests is to examine the components of each technology, e.g. the referee’s watch, the field tests aim primarily at evaluating their robustness in different weather scenarios and match situations. Only if the system fulfils all the necessary criteria will it be registered by FIFA as a licensed goal-line technology system.

Final installation test

This final step in the process verifies the proper installation of the licensed goal-line technology system. The installation test aims to establish the perfect functionality of the system by certifying that the technology performs to the same level in the stadium as it did during the system test. Following a successful installation test and approval by the customer (e.g. the competition organiser), the GLT system will then appear on the official FIFA list of certified installations.

Aftercare

Once the system has been tested, the challenge is to maintain the upkeep of its quality and functionality. Aftercare is an essential part of the sustained quality assurance of the GLT system, which is why its service provider must commit to performing regular post-installation maintenance.
As a final precaution, additional system checks must be carried out by the match officials prior to every official match.

What technologies exist?

As is the case for all FIFA Quality Programmes, goal-line technology systems must fulfil specific technical criteria in order to receive a licence. Consequently, different technical solutions have fulfilled the requirements, giving competition organisers the choice between different technologies.

Camera-based

Several approved systems work with cameras that detect the ball and then use specific software to evaluate the footage from all the cameras. This way the system can determine whether or not the ball has crossed the line entirely. Currently licensed systems work with seven cameras per goal installed as high up as possible within the stadium structure.

Magnetic fields

Several systems operate using magnetic fields. For these systems, cables are placed underground and around the goal and the ball has elements of the technology inside. The interaction between the receptors in the ball and the magnetic fields created through the underground cables allow the software to calculate the exact position of the ball and thus determine when a goal has been scored.

 

 

Goal-line incidents

Goal-line incidents can occur at all levels and in many different situations. The following examples show how difficult it is to judge whether or not the ball has crossed the line – even with the help of several replays and camera angles.

More than the “Wembley goal”

Although they were undoubtedly the most publicised incidents in football, the two goals involving England and Germany in 1966 and 2010 dominate the discussion and perception of the typical goal-line incident. In recent years there have been many more such situations that do not involve a ball rebounding off the crossbar. The following videos show a variety of goal-line incidents from the past couple of years.