A man has been arrested following this morning's crash on the SDR.
A Gwent Police spokeswoman a 39-year-old driver had been arrested for driving without due care and was in custody.
She added the road had been cleared and the lorry moved.
One ambulance was also called 9.54am.
Two Maesglas men who were travelling behind the lorry when it overturned helped to pull the driver out of the cab.
Luke Dowsell, 24, said: "We were driving about four cars behind. We heard a noise and thought it clipped the curb. If there was a car by the side it would've been crushed."
Jordan Reynolds, 23, said: "Some man chucked me up on the top of the cab and I opened the door and tried to get him out. It was a bit difficult at first, he was looking for his phone."
Mr Dowsell added: "There was diesel leaking all over the floor. It could've caught on fire, it was risking our lives."
"I wanted to get off the top as well, I didn't want to be there just in case," Mr Reynolds added. "We didn't know what's gone wrong, if there were any electrical faults or anything."
A South Wales Fire and Rescue Service spokesman said they received the call at 9.57am and sent three crews from Malpas, Maindee and Ely to the scene.
The fire service made the scene safe and left the incident in the hands of police and the local authorities at 10.52am.
The spokesman said no-one was trapped on arrival.
AN overturned lorry has partially blocked the SDR in Newport this morning.
The incident happened on the Leeway Roundabout.
Emergency services are at the scene.