16.02.2023 • Author: Lena Fleischmann
In this blog we have already delved into the history of sports technology with you. In the current article we want to go into more detail about a new, very special tool in football: the goal-line technique. Anyone who follows the news regularly has certainly been made aware of the highly controversial refereeing technique. Goal-line technology is intended to help referees in the game to correctly assess situations and avoid wrong decisions. Because in addition to the well-known Wembley goal, there have also been other controversial decisions in the past.
An example of this is the phantom gate of Sinsheim. Bayer 04 Leverkusen were guests at TSG 1899 Hoffenheim on matchday 9 of the 2013/14 Bundesliga season. When the score was 0-1 for Leverkusen, the visiting team got a corner. Stefan Kießling headed the corner kick past the left post, but to the astonishment of the spectators the ball still landed in the goal because it flew through a hole in the net and into the inside of the goal. In the 70th minute, Felix Brych scored a goal for Leverkusen, who won the game 0:2. It was clear to everyone that the referee had made a clear mistake and Hoffenheim lodged a protest, which failed at the DFB sports court. This goal caused a great uproar and made headlines in the days that followed.
Another exciting event occurred in the 2010 World Cup round of 16, in which, as in 1966, Germany and England met on the pitch. With Germany 2-1, a deflected shot from Frank Lampard bounced off the crossbar and bounced off the ground and out the front of the goal. Uruguay’s Jorge Larrionda disallowed the goal and allowed the teams to continue the game. A short time later, slow-motion recordings brought certainty – the ball was clearly behind the goal line. England were denied the goal and Germany advanced 4-1 to the quarter-finals. A similar event could be followed in 2013 at the season opener of TSG 1899 Hoffenheim against 1. FC Nürnberg. Shortly before half-time Hoffenheim led 2-0. Suddenly Kevin Volland scored a goal, which also jumps out of the goal due to the spin. The referee at the time, Thorsten Kinhöfer, denied the goal and Nürnberg managed to equalize to make it 2-2 as the game progressed. The game ended in a draw. This led to a big debate as it was questionable whether the game would have ended like this if Hoffenheim had taken a 3-0 lead. Kinhöfer said the following in an interview after the game: “It was only when I saw the pictures on TV that I realized it was a mistake. Where people judge, mistakes happen. We referees would appreciate it if this story were taken from us. But that’s not the case. So we have to make decisions – and unfortunately they were wrong this time.”
Before we can assess the use of goal-line technology in football, we also need to consider its impact on the referee. To do this, you need to understand the responsibilities and tasks of a referee. In the professional sector, they have a full week with little free time. At least every second day, they train to prepare for the upcoming game. The referees arrive the day before the game and since most games take place in the evening, they don’t leave until the next day. They are therefore on average 3 days on the road for a game. There are also courses, bases and other events. Most of the time, the referees are on the road throughout Germany. Sometimes they are also used twice a week when important events such as a cup game or an international Champions League game are taking place. The journey also brings hardships and stress. Not to mention that there is little time left for family and personal interests. Very few referees can do this full-time and also have to practice another profession, which also involves deadlines and obligations. The DFB wants to counteract this and wants to increase the fees of the referees and bind them contractually to the association, because as early as 1981 the DFB recognized the lack of qualified referees and advertised with the slogan “Be fair to the 23rd man – it doesn’t work without a referee! ”.
The referee also has a variety of tasks on the field. In order to keep an eye on everything, he must always be up to date with what is happening in the game. With 10 to 15 high-intensity running kilometers per game and up to 50 sprints in between, this represents a very high level of physical strain. Referees also have to train a lot in addition to their work in order to be able to keep up with professional footballers. The DFB determines this physical resilience with performance tests, which a referee must complete before being used in professional sport. In addition, he must not only run fast, but also be able to judge. The decisions that a referee has to make in a few fractions of a second must be factually correct. Not only the players expect that, but also the coaches, fans and also companies and associations, because a wrong decision can have a major impact on the marketing of a club and the income for them from TV rights. They are constantly being watched by thousands of people in the stadium and in front of television, cameras and the media. A great psychological pressure that one does not like to be exposed to. In addition, there are the consequences of an avoidable wrong decision. Everyone has seen players verbally abuse or spit at the referee. In the past, games have also been abandoned because fans threw a full beer mug at an assistant referee, causing him to fall to the ground. In order to better protect the referees and reduce the pressure, further tools have been introduced.
The following tools are intended to support the referee in correctly assessing game situations and minimizing the number of wrong decisions in football. These can be divided into technical and non-technical tools:
In addition to the whistle as an acoustic signal, the non-technical aids also include the assistant referees. They are also called linesmen and are on the touchlines during a game. The assistants’ duties are to signal foul play, handball, offside and balls on touch and behind the goal line. There is also another helper in the team of referees – the fourth official. This was introduced in the 2002/2003 season and monitors substitutions and overtime at the end of both halves. Another task of the fourth official is to keep the emotional expressions of coaches and officials in check and to have de-escalating conversations with them. If this is ignored, he can also dismiss anyone on the bench. Most recently, in 2008, goal-line referees, non-technical support before the introduction of goal-line technology, were used for the first time. These should officially be used to support the referee in all decisions in the penalty area.
The referees’ first technical aid was the radio system introduced in 2013, consisting of a headset for verbal communication and a vibrating bracelet for connecting to the flags of the assistant referees. If they press a button on the flag, the referee gets an acoustic signal and a vibration signal on his upper arm. In the event of an offside situation, the referee can therefore continue to concentrate on the game and does not have to look away to hear the decision of his assistants. All officials are also equipped with the headset to make it easier and faster for the referees to consult with each other. It is therefore possible for them to communicate throughout the game and to assess what is happening in the game. Many referees can therefore no longer imagine their work without this simplification and saving of additional walking distances. Another technical aid is the goal-line technique. This technique is very complex and will be presented extensively in the next section.
Two different systems are used in goal-line technology. On the one hand, this is a ball location using a chip in the ball, which conveys its position using an electromagnetic field, and on the other hand, through the use of camera systems. The FIFA-licensed chip-based systems include GoalRef and Cairos. Using weak electromagnetic fields around the goal, the GoalRef system can detect whether the ball has crossed the goal line. This field is generated by ten antennas located behind the crossbar and posts. GoalRef is similar in its function to a “radio light barrier” – only for the ball. In order to generate a change in the electromagnetic field around the goal, thin coils have to be installed in the ball.
This allows the system to recognize where the ball is between the goal line, post and crossbar and send a real-time signal to the referee’s watch. In contrast to GoalRef, the Cairos system uses two electromagnetic fields. For this, thin cables have to be laid through a 15 centimeter deep incision in the floor of the playing field. In addition, more cables are laid in the goal housing, which makes the use of this technology a bit more difficult. Thanks to the two electromagnetic fields and a chip in the ball, Cairos can calculate where the ball is on the field at any time. If the system registers that the goal line has been crossed, it also transmits the information to the referee’s watch. To ensure that the chip is firmly anchored in the middle of the ball and does not change its position during the game, it is held in place by twelve glass fibers. With this complex technology, the manufacturers can guarantee that Cairos is still 100% accurate even with limited visibility and disruptive external influences.
Compared to chip-based systems, the camera-based systems offer a major advantage, since they can also visualize the decision for the spectators and thus ensure greater transparency. The Hawk-Eye technique, which has been given the name “Goal Decision System” in football, is already known from other sports. The English Premier League’s system uses high-speed cameras, which capture more than 100 frames per second, to track the position and trajectory of the ball. A computer evaluates the recordings in the background and sends the result to the referee’s watch. Furthermore, the decision can also be shown on the screens in the stadium with the caption “GOAL” or “NO GOAL”. The animation is very detailed and therefore easy to understand for the viewers. A very similar technique was also developed in Germany – the GoalControl 4D system. This is based on 14 cameras, which are also positioned around the pitch and some of which also have to be attached to the stadium roof. Seven cameras are aimed at each goal.
A computer analyzes the movement of all objects on the field, ignoring disruptive factors such as the players or the referee. The ball is continuously tracked by the system and automatically captures it as soon as it approaches the goal line. As with all other goal-line technology, the computer again sends a signal to the referee’s watch when crossing it. The camera images can be recorded and stored so that they can also be used on the stadium screens and in the media.
Due to the generally advancing mechanization in all walks of life, football will also have to adapt to the introduction of further aids. As with many innovations, this of course always meets with headwind at first. Therefore, new techniques are first tested to find out their effectiveness and benefits. A bit of skepticism is appropriate here and not all referees are completely convinced of the use of goal-line technology in the game. The majority, however, expressed themselves very positively and can no longer imagine working without technical aids. It relieves them of the pressure of making wrong decisions and gives them the opportunity to concentrate on important game situations. The authority of the referee should not be undermined either, as there are only one or two situations in each game where goal-line technology is used and provides certainty for all involved.
The future will show what opportunities technologies like these bring to the sport and, in contrast, there will always be situations in which they provide a lot of material for discussion. We will of course keep you up to date on this – so stay tuned and follow us on Instagram, Facebook or LinkedIn!
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