The incident happened on Thursday afternoon at Cameron Toll in Edinburgh after the lorry struck a bridge shortly after 2.45pm.
Emergency services are currently at the scene and the road is closed.
One witness who took a picture of the the lorry said: “It was at the Prestonfield Roundabout at Cameron Toll - I took picture at 3.20pm today.
“One of the rescue team told me that the lorry’s load was too high and the bridge tipped him over.
"It caused huge tailbacks on Prestonfield Road from Niddrie and Old Dalkeith Road from Edinburgh.”
A Police Scotland spokesperson said: "We were made aware of a crash involving a lorry which struck a bridge at Cameron Toll in Edinburgh shortly after 2.45pm on Thursday, 16 September, 2021.
"Emergency services are currently at the scene and the road is closed."
As a result of the incident, delays are expected on Dalkeith Road, Peffermill Road, Minto Street.
Bus services such as the 24, 38, 49 are being diverted as well as the 33's and 42's.
For further information on diversions, visit Lothian Buses service alerts page.