Those driving between Christchurch and Ashburton will notice Rakaia's busier than normal

Contractors are starting to build a split site Commercial Vehicle Safety Centre, previously called weigh stations, just north of the Rakaia River.

They're sites where enforcement officers can do checks on vehicles and drivers.

It comes after local trucking companies raised safety concerns about heavy vehicles pulling out onto State Highway 1 in 2020.

Waka Kotahi regional relationships director James Caygill says the centre is being built with facilities on both sides of the highway, so truck drivers only need to turn left in and left out.

Both sites are set to be complete and operational by the end of 2024.