A section of the Northwestern Motorway in Auckland will be closed tonight.

The closures relate to the construction of the Great North Road Interchange to connect the Northwestern and Southwestern motorways.

NZTA highways manager Brett Gliddon says the motorway will close so that preliminary works on one of the four interchange ramps can be performed safely over the motorway, with no risk to drivers.

He says they are getting ready for an operation starting next month to place long concrete beams weighing around 60 tonnes over the motorway.

The motorway closures start at 10pm and will affect drivers travelling in both directions.