It will help improve the journey between the city and Nissan and and the new International Advanced Manufacturing Park, boost regeneration, make it quicker to and from the A19 and reduce congestion.
The next part of the work will begin on Monday, March 15, when the construction team will carry out surfacing, road markings and traffic signal installation on the new carriageway on Trimdon Street.
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Work there has involved widening the road between the shops and homes nearby.
The A1231 will be closed in both directions from Hylton roundabout to Beach Street between 8pm and 6am.
A signed diversion will be in place taking traffic along the A1231 eastbound and then via Beach Street along Farringdon Row.
Traffic heading along the A1231 Westbound will be diverted via Hylton Road towards Pallion.
The A1231 will be re-opened each morning at 6am and Beach Street closed.
A spokesperson for Sunderland City Council said: “The benefits of carrying out works on nightshift means there is no disruption to traffic with road closures to Trimdon Street during the day, and also reduces the potential duration of the works.
"We realise that some disruption could be caused during the work and assure you that we will use our best endeavours to ensure that the impact to you is kept to a minimum.”
The SSTC3 route runs along the south side of the River Wear and features a new Western entrance into the Pallion Shipyard site, a crossing under the end span of the Queen Alexandra Bridge, new junctions in the Simpson Street Area to Pallion New Road and Beach Street, improvements to Hylton Road and St Mary's roundabouts, new shared use footpath and cycle paths throughout, the reworking of streetscapes at Alliance Place and Carol Street and landscaping.