Senior Sergeant Anthony Bond said an 18-year-old man was driving towards Mosgiel in a ute with a trailer yesterday about 4.10pm.
He tried to brake after his trailer full of soil began to fishtail.
The vehicle crashed and became wedged on to a median barrier.
While attending, police observed another man who was rubbernecking and filming the incident, Snr Sgt Bond said.
The man was given an infringement notice for using a cellphone while driving.
The incident served as a reminder to concentrate on driving and not be distracted, as such behaviour could have caused another crash, Snr Sgt Bond said.
A Fire and Emergency New Zealand spokeswoman yesterday said three crews attended.
A police spokeswoman said no serious injuries were reported and one southbound lane of the motorway was closed for a time.
