London is set for a test run of the new Night Tube this weekend ahead of its official launch next week.
On an operational basis only, without customers, trains will run on Friday (August 12) and Saturday (August 13) night for Transport for London (TfL) to make checks.
It will only run on the Central Line and Victoria Line as part of the trial.
The official launch of the Night Tube on August 19 , which was originally set for September 2015, comes after a string of delays after tube strikes from the RMT and TSSA.
It will begin on the Central and Victoria Lines before expanding to the Piccadilly, Jubilee and Northern lines in Autumn.
Mayor of London Sadiq Khan is set to release details about how "outer London" stations on the new service will be policed .
It follows a City Hall meeting where Conservative Assembly member Andrew Boff quizzed Mr Khan and used stations in Ealing to highlight some of the challenges.