The Eunony Bridge will be out of action for six months starting from the early hours of Friday morning.
Wagga City Council's $10.6 million upgrade to allow heavier vehicles to cross over the bridge will mean vehicles accessing Bomen and North Wagga will be detoured via Wagga until August 1.
Barriers will be erected at both sides of the bridge at 12.01am to stop traffic crossing.
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Therefore drivers will need to prepare for thousands of extra cars and trucks detoured through Wagga each day.
Although the majority detoured will be passenger vehicles, council's project manager Silas Darby said there will be an additional 3000 trucks travelling on Edward Street each week.
Mr Darby said he anticipates the roundabout joining the Olympic and Sturt highways will be congested in the early morning and late afternoons when truck movements are more frequent.