The obligation to record driver's activities was introduced in 1969, for social and road safety reasons. Recording was made via a paper book on which drivers were supposed what they did each working day.
Tachographs were introduced around 1985. Over this time the Tachograph has evolved. In the early days there were mechanical Tachographs, which progressed to the early electronic units, but these were subject to interference by unscrupulous users. In order to combat this interference some amendments were made to the regulations that required diagnostic features to be incorporated into the Tachograph, and for the signal cables to be armoured to prevent tampering.
All of these analogue units record the driver’s periods of duty on a waxed paper disc - a Tachograph chart. These are not always interchangeable between the different units and are vulnerable to damage and tampering.
The EU wanted to take advantage of technology now available in order to ensure the security of the recording of the driver’s duty periods. This introduced the Digital Tachograph. The aim was for the Tachograph to be less vulnerable to illegal acts by users to distort the data. The new system also allowed for easier and better control of driver's hours by operators and the enforcement authorities.
Digital Tachographs became mandatory in new vehicles with a kerb weight greater than 3.5 tonnes from May 2006. These electronic devices record drive, rest and break periods. There is no requirement to retrofit them to vehicles manufactured before May 2006 and in most cases these vehicles can continue to use conventional analogue Tachographs.
Digital Tachographs store data in memory (vehicle data) and by recording to an official driver card (driver data) inserted into the digital Tachograph unit during the period the vehicle is being driven. To obtain a driver card one must apply to the DVLA. Operators must periodically download data from the digital Tachograph and from the drivers' card and analyse them to check that EU rules and regulations have been complied with. Should a driver use both digital and analogue equipped vehicles then a continuous record of driver's activity must be assembled and made available for inspection for a period of up to 12 months.