Maesdu bridge at West Shore was scheduled to open in July but has been delayed by 10 weeks.
Construction work on the new bridge, which crosses a railway line, began with the demolition of the old structure in October last year.
The old bridge, built in the 1920s had deteriorated and had a 7.5 tonne weight limit for vehicles.
There were concerns about the "structural integrity" of the bridge and steps taken to stop "deteriorating concrete" from falling onto the railway
Final finishing works will take place next week, but traffic flow should not be affected.