The results of a study carried out for the Swedish Transport Administration on fire detection in road tunnels is presented. Laboratory tests and numerous large-scale tests were carried out in order to verify a proposal for a test method for fire detection systems. The main aim was to investigate possible fire detector systems and to see if they could fulfil the requirement given by the Swedish Transport Administration to detect the fire within 90 seconds. The tests are presented as well as a recommendation for testing detection systems in Swedish road tunnels. In order to perform the fire test, pans of different sizes were tested in order to obtain a reasonable fire size. The method proposed requires the use of three 0.6 m diameter standard pans, each containing eight litres of 95 octane gasoline, and air flow velocities of 2 m/s and 6 m/s. It was found out that using only one 0.6 m pan is sufficient if early warning is required without identifying the position for the fire-fighting system.