The Alcolock or alcohol ignition interlock is a device installed in the vehicle, requiring the driver to provide a breath sample before starting. If the sample alcohol concentration is above a specified threshold value, the ignition is locked and the vehicle cannot be started.
Alcolocks may be installed in any vehicle but so far have been used mainly in public transportation, in particular buses and company cars. They may be used as a general measure or as part of a rehabilitation scheme for drivers known to be repeat offenders.
Drivers are prevented from driving while under the influence of alcohol.
Alcolocks used in public transportion must be reliable in order to avoid schedule delays or cancellations. To prevent problems due to malfunction, a test phase is recommended before complete implementation, with an override switch installed in some of the vehicles. It is recommended to include the drivers and their unions in the implementation of the alcolock from the very beginning, to ensure driver acceptance and make use of their practical input. Further implementation will depend upon the accident-reducing effect of alcolocks in public transportation, as more research concerning this issue is needed. Legislation concerning the use of alcolocks in public transport must be developed. Random retests during driving are not recommended for public transportation. Breaks without a retest should be as short as possible, preferably under 20 minutes. The test results should be easily observable. The device should give a clear signal to both the driver and the operations manager. Manufacturers should consider how to provide the results to the operations manager quickly and simply. A clear signal means less time need be spent downloading and reading data.