Work to repair a sinkhole is expected to cause travel disruption for at least another day.
The hole opened on the northbound carriageway of the A47 in Lowestoft on Monday, just north of the Bascule Bridge.
Investigations have found it was caused by a collapsed sewer and a team from Anglian Water is working on the repair.
A Highways England spokesman said the work was “extensive” and would last until the evening.
Anglian Water is working to fix the problem “as quickly as possible”, a spokesman said.
BBC Radio Suffolk reporter Guy Campbell described the hole as “about the size of a dinner plate”.
Drivers in the town have complained of disruption to their journeys.
A signed diversion for northbound traffic is in place and, if safe, a contraflow system may be put in to allow traffic to run in both directions later on Tuesday. The southbound carriageway is open.
“We don’t know what has caused the sinkhole, but our investigations have found a section of sewer pipe which needs to be repaired under the damaged road,” the Anglian Water spokesman said.
“Due to the location of the pipe and a number of other utilities nearby including gas and electricity, this is a complicated repair which will require careful excavation, by hand, before we can begin any repairs to our pipework.”