Exactly one week after Tia Sharp went missing, police are stopping vehicles entering and leaving the New Addington estate.
Officers are quizzing drivers about the 12-year-old's disappearance and handing out leaflets bearing the schoolgirl's picture.
Uniformed officers were also seen on local bus routes talking to passengers about Tia.
It is understood the police are taking the names and addresses of drivers and their passengers, on where they were last Friday.
They are also asking for any information that could help them trace the schoolgirl's last movements.
Elsewhere on the estate officers have continue to search bins as refuse collections resume.
The Mitcham 12-year-old Tia Sharp went missing from New Addington on Friday afternoon.
Earlier today Christine Sharp, Tia's gran was taken away by two detectives. She was not was not under arrest.
Anyone with information should call the incident room on 0208 721 4005 or Missing People on 116 000 quoting reference 12MIS025216.