NZ Transport Agency contractors will be working on nine bridge sites over a 2-kilometre stretch of the Manawatu Gorge.

Motorists will experience delays in the Manawatu Gorge for the next three months while contractors carry out bridge maintenance.

Crews will be working on nine bridge sites over a 2-kilometre stretch of the gorge, working on one bridge at time.

From Monday , between 9am and 4pm, a small section of the gorge will operate as a single lane, controlled by temporary traffic lights. At these times, including weekends, motorists can expect delays of 5 to 10 minutes.

Between 4pm and 9am, the gorge will be open to two lanes. There will be a temporary speed limit of 30kmh at the work site.

NZ Transport Agency highway manager Ross I'Anson said the work was expected to take three months, depending on the weather.

"Much of the maintenance work is taking place under the bridges, so crews won't necessarily be visible from the road.

"We appreciate people's patience while we ensure that the bridges on this route are safe and resilient."

I'Anson said NZTA worked hard to minimise disruption to traffic, while still allowing crews to do the required maintenance work safely.

"We considered whether we could undertake the work at night when traffic through the gorge is less frequent, however this is not possible due to the nature of the work."

Motorists can keep up to date on the status of the gorge through the NZTA's website, social media channels, and electronic variable messaging signs at Ashhurst and Woodville.