People using State Highway 29 over the Kaimai Range during the next two weeks are being warned that there will be considerable delays.

From Monday, June 19, Omanawa Bridge will be down to one lane and stop/go management will be in place while essential strengthening work is completed.

The bridge was constructed in 1935 and is the oldest bridge on the Kaimai Range.

NZ Transport Agency Highways Manager, Niclas Johansson says the Transport Agency would like to apologise in advance for the delays the work may cause.

'We have carried out extensive investigations to find a repair method that has the least impact to people's journeys and have been able to keep one lane open.

'However people should avoid the area if possible or expect delays and allow extra time when they are travelling over the Kaimai Range.”

As there are no short detours for this route drivers heading between Hamilton and Whakatane and between Taupo and Tauranga are being encouraged to avoid the Kaimai Range and use SH5 / SH30 or SH36 / SH5 via Rotorua.

For people in cars an alternative route is via Poripori, Crawford and Wairoa Roads to SH2, which will add at least 10-15 minutes to travel times to Tauranga.

The first lane closure will be from 7am on Monday, June 19, reopening by 7pm Friday, June 23.

The second closure will be the following week from 7am on Monday, June 26, reopening by 7pm Friday, June 30.

There will be 24-hour stop/go operation in place and a 30km/h temporary speed limit.

In the event that works are completed earlier than planned each week, the lane closures will be removed. These works are weather dependent and may extend into the following week.