Goal-line Technology: How Does it Work?

TechGoal-line Technology: How Does it Work?

Goal-line Technology: How Does it Work?

Turn on an international football game and you’ll like see goal-line technology in action, though you might not realize it. The process aims to remove much of the human error from the game by automatically tracking the position of the ball to see if it has crossed the goal line and scored a goal. How does this innovative technology work?

In essence, goal-line technology uses data gathered from multiple sources to track the path of the ball and detect when it completely crosses the goal line. In most cases it is fairly easy to see if a goal has been scored, but fast-paced plays, rebounds, and saves can make it hard for referees to make a decision by eye—that’s where goal-line technology comes in.

Since 2012, FIFA and the International Football Association Board (IFAB) have approved the use of certain systems in official games. Certified installers must verify their systems using a special test, which takes into consideration the many variables in each stadium, such as lighting, climate, and architecture. Because goal-line technology is expensive to install and maintain, it is currently only used at the highest level of the game, including in top European leagues and the Men’s and Women’s World Cups.

Camera Tracking and Other Tools

One common method for tracking the ball is to use camera technology. Hawk-Eye, the first ball-tracking technology in action, uses cameras to triangulate and track the ball’s location. With seven cameras pointed at each goal, Hawk-Eye can still be effective even if a few of the cameras are blocked. This program has been used in cricket and tennis and throughout the Premier League.

Another option is GoalControl, which was used during the 2014 World Cup. It uses 14 high-speed cameras mounted throughout the stadium to track the flight of the ball and to see if it crosses the goal line. All Fifa stadiums that use camera tracking programs either use Hawk-Eye or GoalControl. Some technology, like Goalminder, uses cameras embedded in the goal posts and crossbar.

Magnetic Field Tech

Another wave of technology relies not on cameras by on a magnetic field of wires installed underneath the goal area. With the Cairos GLT system, a sensor is placed inside the ball that can detect the magnetic field created by a series of wires running underneath the penalty box. The sensor communicates with a computer program to track the ball’s location and when it crosses the goal line. Another program, GoalRef, uses a similar magnetic field but uses sensors in the goal frame instead of the ball to determine a ball’s location within the goal.

A football player tests a new high tech system for soccer that has a microchip built into
Image: Dated back to 2003: A football player tests a new high tech system for soccer that has a microchip built into the shin pads of all 22 players on the pitch and also inside the ball. A German company is working on the system that could one day help referees on close and controversial calls, such as whether the ball crossed the goal line, whether the offensive players were off-sides or whether the ball went out of bounds. A test ball (background) is filled with foam to protect the microchip, but later the chip is supposed to be able to float freely inside the air-filled ball. Picture taken at Fraunhofer Institute for Applied Electronics Erlange. REUTERS.

With most systems, the decision ultimately comes down to the referee to determine whether or not a goal has been scored. In most cases, referees get an encrypted alert on their watches within a second of the goal line being crossed.


Although goal line technology helps remove some degree of human error, it isn’t a perfect system and has faced some controversy. In the 2014 World Cup group-stage game between France and Honduras, the referees received two alerts about possible goal-line crossings; the first when the ball had just crossed the line, and the referee gave a goal to France. Another alert showed the ball cross the goal line only after hitting the goal keeper, which greatly confused coaches and media commentators. In response to the game, FIFA issued a statement saying it would review how the technology affected the game to see if things needed to be changed to create a better and less confusing experience for fans and coaches in the future.

Goal-line technology has received criticism, including from top FIFA officials, for removing much of the human element from the game. While other sports have changed their rules of play based on new technology, football has long prided itself on staying true to its roots. Goal-line technology has yet to be used in the American MLS, largely because of the high installation costs and the per-game usage costs.

Goal-line technology aims to make football a more objective sport and seems to be having good success so far. With an understanding of how this technology works, fans can better relax and enjoy the action between their favorite teams.