His advice comes after a truck became wedged under the Humber St rail bridge in Oamaru last week. The clearance height is 3.5m.
It was the third time a truck had come to grief at the bridge since 2014.
Drivers needed to be aware of their vehicle and load sizes when they approached the bridge, Mr Harrison said.
‘‘It’s very important for anyone driving a vehicle to know what size the vehicle is and to follow the signage.’’
He was now investigating whether there were ‘‘additional features that could be installed that would make a difference’’.
He declined to elaborate on what those might be.
The clearance height is clearly displayed on the bridge itself in both directions of Humber St, but there are no clear warning signs advising drivers to approach with caution.
He did not think that was a factor in Thursday’s accident.
‘‘In this case, it was a rigid-body truck, so it wasn’t even a load ... it’s not like it’s a flat-bed truck that’s had a load on it, or an excavator has been loaded on it. This is one where the driver has made a choice.
‘‘People don’t often obey signs ... so we have got to build an environment where people choose the desired outcome.’’
In July 2018, a southbound H&J Bruce Transport Ltd truck struck the bridge, stopped and toppled on to its side, blocking the northbound lane.
In 2014, a northbound New Zealand Vehicle Deliveries Transport Ltd transporter truck carrying several cars also came to grief.
Two cars, including a black Audi, were shunted off the truck and badly damaged.
