Future jobs in heavy industries like freight rail transport will require a unique mix of industrial and digital expertise, according to Jamie Miller, CEO of General Electric’s $5 billion transportation business.

Freight trains weigh in at 440 million pounds, and combine the brute strength of their GE locomotive engines with computers and increasingly complex software, said Miller who spoke at Fortune Brainstorm Tech on Tuesday. Modern freight trains use a large amount computing power.

A GE trip optimizer, for example, monitors data about engine performance, the condition of the tracks, and constantly tunes the engine as the train operates. That, Miller said, results in 10% fuel savings for GE customers.

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“If you understand physics of how a locomotive works, that knowledge is irreplaceable,” she said. “If you’re industrial person with a digital capability you can transform an industry and yourself. It is hard for a digital person to become an industrial.”

Miller, who is also a senior vice president at parent General Electric ge , said the company has reinvented the engine repair business in a way that minimizes cost and the time of engine repairs.

“We used to take a used locomotive engine, tear it down, rebuild it and put it back out there,” she said. “We treated all the engines the same. Today, before the engine hits the shop, we know the condition of every part and component, which have had no wear and tear and which need to be reworked or remade.”

As a result, GE cut 20% of the time from that process this year, she noted, which means railroad customers get their engines back to work faster.

Asked if GE would benefit if the Trump administration passes a massive infrastructure bill, Miller said it would be key to group digital infrastructure with the usual road-and-bridge improvements. While she did not specify, digital infrastructure may include things like improved broadband network connections and faster wireless.

“Talking about the infrastructure bill, we advocate that it not just be about heavy industry but add a level of digital into infrastructure spending,” she said. “Jobs are changing. Jobs will be about the blending of the digital and industrial capabilities.