Built Robotics, a company aiming to make construction equipment autonomous, is announcing a $33 million Series B round this morning.

With the construction industry facing a global labor shortage, Built’s aim is to allow one equipment operator to oversee a fleet of vehicles working autonomously in parallel, hopping in the cab only for tasks the machine can’t handle.

Rather than building its own vehicles, Built focuses on converting the popular construction equipment that’s already out there. They sell a kit that straps to the top of things like excavators, bulldozers and skid steers, taking tech like lidar, GPS and Wi-Fi and meshing them into the machine’s innards to give it autonomous smarts. They sell the conversion boxes to other companies, help them get installed, then charge a usage fee whenever the machines are in autonomous mode.

No one wants a 20-ton piece of machinery blasting around a construction site without a care for those around it, so the autonomous machines try to keep a constant eye on their surroundings. As I wrote back in April:

Cameras on and around the vehicles are constantly checking for anyone who might stray too close. If something goes wrong and the machine starts to tip too much, or if on-board sensors detect that something is in the way underground? Power gets cut. And there’s a big red emergency stop button on the back of each machine (and a wireless button meant to stay on the operator’s desk) for good measure.

We also took a look at some of Built’s gear a few months back:

The round is lead by Next47 (the investment arm of the European mega company Siemens), along with Building Ventures and previous investors Founders Fund, Presidio Ventures, Lemnos and NEA. As part of the deal, Next47’s T.J. Rylander will be joining Built’s board of directors.

The company had previously disclosed a $15 million Series A it raised in 2017, bringing its total funding up to $48 million. Built co-founder Noah Ready-Campbell tells me that the company has roughly doubled in headcount over the past few months, with the team now sitting at roughly 40 people.