The invention relates to a method for determining a source of danger on a travel route. According to the method, a vehicle parameter (101, 201) is measured during travel of a vehicle along the travel route and is compared to a vehicle parameter threshold value (103, 203). Danger data comprising the measured vehicle parameter and a vehicle position associated with the measurement are formed on the basis of the comparison in order to provide information that a source of danger is formed (105, 205) at the vehicle position associated with the measurement. The invention further relates to a corresponding device (401) and a corresponding computer program.