A man broke his leg when he came off his motorbike near Hadleigh.
The rider, believed to be in his 60s, was involved in the accident at 3.30pm by the junction with Lady Lane.
The East of England Ambulance Service attended and called for an air ambulance to arrive.
A police spokeswoman said the rider had initially complained of chest and thigh injuries.
An ambulance spokeswoman said he was taken to Ipswich Hospital on a land ambulance with a broken leg.
The road was re-opened at around 4.30pm.
At around 4pm a man riding a Harley-Davidson was in collision with a Citroen Advantage which was turning left on the A12 at Blythburgh.
An off-duty nurse assessed the rider at the scene who was complaining of an injury on his left side.
A police spokesman said he was taken to hospital with “soft tissue” injuries.
The crash caused delays in the area for a time.
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