Cover Story: Terex Trucks TA400 ADTs

By: Cameron Officer, Photography by: Cameron Officer

BOSCO runs two Terex Trucks TA400 ADTs up and down the steep slopes of Horokiwi Quarry, near Central Wellington

Whatever the vista out your office window, there is precious little that will compete with what the upper reaches of Horokiwi Quarry has to offer.

Horokiwi -Quarry

Thanks to the unique terrain surrounding the Capital, Horokiwi Quarry can exist—as it has done for decades—seemingly right next door to the Wellington CBD.

It isn’t, of course, but such is the elevation you rise to as you power 260 metres up the hill behind the main asphalt production area that all of a sudden, it looks like you could reach out and touch the Cook Strait Ferry Terminal to your right, Eastbourne to your left, or Matiu/Somes Island straight ahead. All the while, directly below, ADTs and wheel loaders speed back and forth like they would in any remote quarry anywhere in the country.

Horokiwi Quarry work

Bryce 's -father -Suds -O'Sullivan

Bryce O’Sullivan Contracting Ltd (BOSCO) has been based at Horokiwi for some time now. And with continuing work along the Kapiti Expressway now joined by the first stages of the mammoth Transmission Gully project—further to the north and directly behind the quarry as the crow flies—Bryce and his team, and the quarry in general, are very busy indeed.

As Bryce’s father (and employee), Suds tells me it’s the blue rock they’re after here, for base course and asphalt. The top layers dug out are used for hard fill. It’s a hive of activity everywhere you look, and Bryce O’Sullivan’s Terex Trucks TA400 ADTs are in the thick of it.

"Porter Equipment was really good to us when we decided to have a look at the Terex Trucks," Suds says. "Josh Hunter, the sales rep there, was so straightforward to deal with. There was no mucking around at all.

"I think those guys recognise the fact that, if an operation is in the market for a dumper like these—or two, as we were—then they need them fast. They aren’t going to kick their heels and umm and ahh about it; they want a good machine for a good price. Porters reacts accordingly."

And so it went for BOSCO. Now, two new Terex Trucks TA400s are steaming up and down the hillside. "Porters supplied us with a demo unit, just so we knew we were doing the right thing. But all-in-all, from the moment we started looking at the trucks to the moment they were on their way to us was about a fortnight. I don’t know if you’d get that kind of action from any other distributor."

Terex Trucks TA400 ADTs


With a maximum payload of 38 tonnes and a heaped load capacity of 23 cubic metres, the Terex Trucks ADTs offer plenty of hauling efficiencies.

The six-cylinder turbo diesels don’t even sound like they’re straining as the trucks head off on their delivery cycle down the nearby access road, but with 444hp (331kW) of power on tap and a massive 2255Nm slab of torque available from just 1300rpm, even hauling aggregate upwards, rather than downwards, wouldn’t be an issue for the ADTs.

The Terex Trucks have had their work cut out for them since arriving on-site. Suds says the crew has taken 200,000 cubic metres of aggregate off the hill since August last year. Blink and the entire shape of a range will change before your eyes. The two BOSCO-operated trucks have around 700 hours on them at this point.


The benches at the top of the Horokiwi Quarry look like they drop away precipitously, but it’s another trick of the eye, as the slopes down towards the highway to Petone are less sheer than you think. Suds says it’s a pretty glorious place to be on a sunny day. In the middle of a winter gale? Yeah, not so much.

Up the top of the hill, a big Hyundai R480LC-9 is feeding the ADTs as they make their runs up and down. This 48-tonne giant sits in the upper reaches of the Hyundai excavator model range offering huge reach and impressive digging dimensions.

The BOSCO business


Bryce has been in business for around nine years now, and BOSCO has become a family affair, with not only Bryce’s father but also Bryce’s partner Becs, her father, and other members of the extended family are all working for the company.

"It’s funny how it has grown like that. Bryce never set out to establish a family business, but it’s just the way it has developed," Suds says.

Outside of Horokiwi, BOSCO runs other civil contracting jobs around the Greater Wellington region, with 45 staff on the books in total (and six on-site at Horokiwi). That’s not bad going for a 25-year old, says Suds.

"He’s doing very well in this business. He’s making some smart moves and he’s always hungry for the work; you have to be though, right?"

He’s also privy to some million-dollar views, which is a bonus in anyone’s books.

Keep up to date in the industry by signing up to Deals on Wheels' free newsletter or liking us on Facebook