The man was trapped when a campervan and trailer collided.
Both lanes over the bridge were blocked and police expected the road to reopen about 6pm and were investigating the cause of the crash.
"We haven't established which way they were travelling. It's not an often-used road nowadays with the other tunnel going through on State Highway One," said Inspector Willie Taylor, Northern Communications Centre shift commander.
A witness reported that the crash was caused when a car towing a trailer jack-knifed and collided with a camper van travelling in the opposite direction.
Timber from the trailer went through the windsceen.
The crash comes just after police issued a caution urging drivers to take care on roads following light rain this morning and more expected tomorrow.
Assistant Commissioner Road Policing, Dave Cliff said after such a long dry period, the build-up of oily residue on road surfaces will create a slippery film when it starts to rain.
"Roads will be extremely slippery for some time and drivers will need to be very careful about speed, following distances and distances it takes to stop."
Mr Cliff says it's also extremely important that people check tyre pressure and tyre tread depth.
"We're asking everyone to take extra care on the roads when the rain does arrive," he said.
- additional reporting Herald on Sunday, nzherald.co.nz
