A three-month detour of State Highway 27 for the Mangawhero Stream bridge project south of Matamata will begin today.

The start of the detour has been delayed slightly to allow for the construction of a temporary roundabout on the detour route.

A temporary roundabout, which was completed overnight, will help safely manage the increased flow of traffic at the intersection of State Highway 29 and Hopkins Road.

"The detour is scheduled to begin on Thursday afternoon, when the construction crew returns after their mandatory rest period after night work," says a spokesperson for the Waka Kotahi Transport Agency.

"The State Highway 27 detour is required to ensure the new sections of road which lead to the replacement bridge can be safely joined to the existing state highway. The new road will be 1.4 metres lower than the existing road, so a 200 metre section of State Highway 27 needs to be cut down and rebuilt.

"The detour route via SH29 and Hopkins Road will add around 3.7 kilometres to a journey between Tirau and Matamata."

Three months has been allowed for the closure to ensure the work can be complete and properly sealed by early April when the new bridge is forecast to be complete.

When State Highway 27 is expected to reopen in April, traffic will be running over the new bridge, with the project fully complete around the middle of 2022.

"The Mangawhero Stream bridge is being replaced because of its high crash rate, with contributing factors the narrowness of the bridge and the unexpected dips and curves in the road leading up to it.

"Waka Kotahi thanks motorists for their patience."

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