Motorists were forced to brake to avoid hitting cones thrown on to a motorway by two drunken men, Birmingham magistrates were told.
Jason Connop (19) of Gravelly Hill North, and Paul Dixie (18), of Jarvis Road, both Erdington, admitted causing a danger to road users. Sentencing was adjourned to December 7 for reports.
Ian Dawes, prosecuting, said the two defendants were spotted walking along the A38 Aston Expressway towards Erdington at about 1.30am on July 19 this year.
He said they picked up four one-metre high cones, which had been on the hard shoulder, and threw them on to a part of the motorway where the lanes split.
Mr Dawes said the defendants' actions were caught on CCTV and when police arrested them near the scene they appeared to be in a drunken state.