Transport police were called out to two suspicious incidents on Mansfield railways in a matter of hours.
On Friday, British Transport Police received two reports from members of the public, at 7.20pm and 7.50pm, that teenagers were sat on the bridge above tracks on Hermitage Lane.
Officers attended the scene soon after the reports were made, but did not find anybody there.
At around 8.45pm on Friday, transport police also received a call that a man was sat on the edge of the platform at Mansfield train station, refusing to move.
A spokesman for British Transport Police said that trains had to be slowed as a result of concerns for the man.
Officers also attended this incident, but the man had left the scene by the time they arrived.