The A140 is currently blocked in both directions after a crane truck overturned in the carriageway in Earl Stonham.
Police were called to the road shortly after 2.30pm, following reports that the truck had overturned near to the junction with the A1120.
It is understood the truck – which is said to weigh 55 tonnes – also collided with two garden walls and a telegraph pole.
A police spokeswoman said two people inside the truck have not suffered any injuries.
No other vehicles were involved.
Highways England crews have arrived at the scene to help assist in clearing an oil spill caused by the accident – although police have been unable to confirm when the scene will be cleared.
Traffic is currently stretching as far back as the A14.
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