Analogue tachographs record the driver’s periods of duty on a waxed paper disc. However, these are vulnerable to tampering, and so are being replaced by digital tachographs which record data on smart cards.
Tachographs are also used to improve road safety and ensure fair competition. They are also used in the maritime world. Rules for this are made by the Central Commission for Navigation on the Rhine.
Tachographs are mandatory for vehicles allowed to carry a total weight of over 3.5 tons and vehicles built to carry at least 9 passengers, if the vehicle is used for commercial purposes. They are used to review the driving and rest time of drivers during reviews by traffic standards organizations or accident investigation. A driver must carry the tachograph records with him for all days of the current week and the last day of the previous week that he drove. Companies must keep the records for 1 year. In Germany, § 16 of the work time regulations lengthens this time to 2 years if the records will be used as proof of work time.
Ghosting is another common trick when false driver information is entered onto a second chart to give the appearance that there is a second driver present in the cab for long distance runs that cannot be completed within a single driver's daily driving period.
Digital tachographs have been implemented in Mexico since 1994, but this is not a federal regulation. The last implementations developed in Mexico have GPS capabilities such as mapping, altitude and location-activated video triggering.
Tachographs are being phased out in favour of electronic log books which record data digitally on a smart card.
When the use of tachographs was imposed by the European Union on its member states in the 1980s, governments and operating companies were opposed on the grounds that tachographs were expensive and unnecessary, and contributed nothing to road safety. Domestic hours regulations were replaced by European regulations which were complicated. It was doubtful whether strict enforcement of these regulations would reduce driver fatigue since they were not based on scientific evidence.
Drivers and their trade unions initially opposed the use of tachographs because they feared that employers would examine the records and reduce the driver's pay for any time stopped, even if the stop was for a good reason, such as checking the vehicle or going to the toilet. This would encourage tired drivers to continue driving rather than rest, and encourage drivers to exceed speed limits in order to reach their destination within the required time.
In some countries, fines to foreign drivers are imposed on the spot, and the drivers may not leave until the fine is paid. In other countries, the driver is required to pay within a time limit. Since collection of fines does not work over the borders, a foreign driver can throw away the demand documents, making the tachograph system less meaningful. The EU is negotiating a system where fines received in an EU country are payable in the home country.
Today operators see tachographs as levellers -- devices which prevent unfair competition from companies who force their drivers to work excessive hours. Trade unions and drivers also now favour tachographs for this reason and records are often used in tribunals as proof when claiming for unpaid work.
Tachographs are also useful after an accident to help establish the cause and corroborate eye witness accounts. Trade unions take a dim view of anyone who exceeds speed limits or permitted hours.
Fears that it is easy to falsify readings by tampering with tachographs have been allayed, since it is relatively easy to spot such attempts.