Before Graham Kennett ploughed into an overpass, sprawling a digger across the Southern motorway causing widespread gridlock he checked the load with his eye.

The Taupo had also never driven further north than the airport and because he'd been under other bridges that day, he thought his load was fine.

After ploughing into the Penrose overpass on May 9 causing traffic to logjam around Auckland, the 66-year-old was charged with dangerous driving.

His lawyer, Simon Stokes, defended the charge at the Auckland District Court in a judge-alone trial today on the grounds the temporary warning system at the time of the incident was inadequate.


Police prosecutor Sam McErlean alleged Kennett saw the warning sign but then made the decision not to move off to the shoulder but into the right-land lane where the bridge was highest.

After a day of evidence, Judge Grant Powell reserved his decision on a verdict until next week.

A truck carrying a tall load, a digger, collided with the Penrose Rd overpass on the southbound lanes of Auckland's Southern Motorway, blocking traffic. 9 May 2016 New Zealand Herald Photograph by Nic
A truck carrying a tall load, a digger, collided with the Penrose Rd overpass on the southbound lanes of Auckland's Southern Motorway, blocking traffic. 9 May 2016 New Zealand Herald Photograph by Nic

The court heard how Kennett's flatbed truck carrying a 15-tonne digger passed through a sensor beam and set off a warning sign 288m before the bridge telling him to "pull over".

However, the single sign was temporary after an earlier bridge strike in March which damaged the former three-alert warning systems. A three-sign upgrade was due to be installed later in the year.

The height limit for the motorway network at the time of the crash was 4.25m and the Penrose overpass - the lowest on the route - stands at 4.41m.

Kennett, who normally drives around Taupo for Higgins, when he picked up the digger from Avondale and considered the height of the load.

But he didn't have an accurate way of measuring it so made sure "it looked flat" with the height of the truck cab. The driver was given a means of measurement two days later.

After reaching the Penrose overpass, Kennett said he'd passed through "five or six" bridges so thought his height was fine.

"I glimpsed a warning sign and it took a little while to comprehend what it actually said and I'm still not really sure."

The sign said "overheight, pull over" but Kennett couldn't see anywhere to move over safely on the hard shoulder.

He said "it was just an instinct" to move into the right-hand lane where the bridge was highest.

"Then the excavator hit the bridge. I sort of sat there like a stunned mullet for a while then people came and saw if I was alright then I asked if everybody else was alright."

McErlean asked the driver whether he accepted it was his sole responsibility to check the height of his truck, which he did.

Haydon Bishop was headed southbound in the right-hand lane and remembered seeing a dump-truck with a flatbed carrying a digger in the lane to the left of him.

The court was shown a number of videos with different angles of the overpass strike.

The bright yellow digger can be seen slamming into the overpass in a cloud of dust as the machine falls onto the road, narrowly missing Bishop's car.

"I heard an almighty bang and I had to react. I was thinking in my head straight away, do I stay or do I go ... I just accelerated through everything," Bishop said.

A specialist traffic engineer witness for the defence analysed the overpass, traffic data and crash history and told the court in his opinion the temporary signage was insufficient and "poorly placed".

Don McKenzie said the temporary sign, placed 288m before the overpass, didn't provide drivers with oversized loads with enough time to realise it was them, move out of traffic and come to a full stop before the bridge.

In his opinion the hard shoulder was also too narrow for heavy vehicles to come to a stop safely.

McKenzie also analysed information for all 21 recorded strikes of the overpass in the last 10 years as well as the March incident and the crash involving Kennett.

Of the 21 with reports, McKenzie said he believed all crashes were a result of drivers being unaware or unable to react to the warnings.

However, when under cross-examination by McErlean - who called that opinion "a bit sweepy" - accepted some drivers were aware they were too high but chose to "run the gauntlet".

Judge Powell asked Stokes whether it was his submission a charge of careless use was more appropriate if he were to substitute the charge.

The lawyer said ideally Kennett would be given an infringement notice but accepted a charge of careless use would be appropriate.