UPDATE 4.10PM: The tail back of traffic over SH29 on the Kaimai range is expected to begin clearing over the next hour.

The road was blocked at about 3pm after a Toyota Hiace and a truck collided on a passing lane near the top of the hill on the Tauranga side.

The van invloved in a head-on crash at the top of the Kaimais. Photos: Luke Balvert.

The highway was blocked in both directions for at least half-an-hour until emergency services had freed the injured van driver.

With the driver on the way to hospital the wreckage was cleared at about 4pm, initially to one lane in both directions.

Earlier:

Emergency services are attending a crash near the top of State Highway 29 over the Kaimais.

Traffic is blocked in both directions after the head-on crash between a van and a truck occurred around 3pm.

The crash in believed to have happened near the passing lane close to the summit on the Tauranga side.

With SH29 highway closed in both directions options for travel to the Waikato are through the Waihi gorge, or south to Ngongotaha, but delays are expected.

Diversions are in place at SH29 and Cambridge Rd on the Tauranga side and SH29 and Raparapa Rd on the Matamata side.

Traffic senior sergeant Ian Campion says on the Waikato side, traffic will be diverted to State Highway 5 to Rotorua and through to Tauranga from Ngongotaha via State Highway 36.

On the Tauranga side traffic is to be diverted at Tauriko. With options of heading down SH36 or for Auckland traffic, to take SH2.

'At this stage there's no indication how long the diversions will be in place,” says Ian.