As Japan’s construction firms are squeezed by the tightest labor market since the 1970s and a rapidly aging population, they are pouring investment into technology — and providing unexpected support to an economy reeling from the bitter U.S.-China trade war.

The industry sees artificial intelligence and robots — which can scurry around building sites day and night, preparing equipment and moving materials for the next day’s construction — as a way to future-proof and close the labor gap.

But a side effect is that one of the country’s least-productive sectors is bolstering capital expenditures even as the world’s third-largest economy flirts with recession amid a global growth slowdown.

Construction company Shimizu Corp., which spent about ¥3 billion ($27.7 million) on robots over three years, is a case in point.

Equipped with state-of-the-art AI, cameras and sensors, the machines handle everything from transporting building materials and welding steel to installing ceilings.

For now, Shimizu estimates the labor savings from the robots in its construction work to be 1.1 percent, far off the land ministry’s goal of a 20 percent productivity boost for the sector by the middle of next decade.

But the company hopes to eventually automate three-fourths of its work as it expands the range of tasks robots perform, said Masahiro Indo, general manager of its construction technology division.

“When it’s hot, workers need to take breaks and drink water. Robots don’t need that as they don’t get tired, so that’s good,” he said. “Once the robots become smarter, we are looking to increase the range of work.”