New Glider buses come into operation today (Monday).
The buses similar to trams, but on wheels, will run approximately every seven to eight minutes, linking east and west Belfast and the Titanic Quarter with the city centre.
The lanes in west Belfast will operate from 7am to 7pm Monday to Saturday.
Although the Belfast Rapid Transit Glider scheme does not officially begin until September 3, the Department for Infrastructure said opening the lanes would give motorists a chance to acclimitse themselves with them.
The introduction over the holiday period has been specifically implemented due to the lighter traffic flow.
The lanes being phased in are Stewartstown Road, Andersonstown Road, Falls Road and Divis Street.
The Glider lanes between East Bridge Street and Dunlady Road in East Belfast will be introduced on July 30. These will be followed by the Belfast Harbour Estate and city centre on August 6.
Drivers are currently in training for the new Glider buses. The new service is the culmination of years of work.