Accidents involving buses and trucks are about 50 per cent more likely to result in death or serious injury as a consequence of the large mass and volume of the vehicles involved. Such accidents should be prevented as much as possible. It needs thus to be ensured that professional drivers do not drive excessive hours and cause accidents due to fatigue.The AETR Agreement is the response of European Governments to fight this silent killer - "Driver fatigue". The AETR Agreement aims to prevent drivers and crews of commercial vehicles of more than 3.5 tons, or transporting more than 9 people, engaged in international road transport, from driving excessive hours. It also defines the control devices (tachographs), sets technical requirements for the construction, testing, installation and inspection of these devices and for checking driving hours by enforcement authorities.The AETR Road Map for Accession and Implementation explains the AETR Agreement, in particular it provides steps for countries on how to introduce the digital tachograph in their international and domestic transport.