The Transport and Road Research Laboratory was an establishment that operated as part of the Department of the Environment, and later the Department of Transport, between 1972 and 1996.

The TRRL was established in 1972 when the Road Research Laboratory was transferred from the Ministry of Transport to the Department of the Environment. At this time, it was also renamed to the Transport and Road Research Laboratory, in order to reflect an increase in its remit from its previous form.

Despite this new name the laboratory would continue its previous work, making use of the priority rule it developed in the 1960s to introduce the mini-roundabout in 1975. It would also conduct a great deal of research in cooperation with several European agencies. As a result, it was involved in the establishment of the Forum of European National Highway Research Laboratories (FEHRL) and was the host of the first meeting.

Beyond its previous research the TRRL would be involved in the development of several software systems that model the traffic at various types of junction.

In 1992 the Transport and Road Research Laboratory became an executive agency of the Department of Transport as part of its privatisation process. It would also be renamed to the Transport Research Laboratory. In 1996 it would be privatised, becoming TRL Limited and trading as TRL.