President Obama has found a new way to invest in America's infrastructure: treating workers on a construction project to burgers.

Obama and Vice President Biden took four employees from a reconstruction project in Washington out to lunch at Shake Shack on Friday afternoon. The White House said the lunch -- a burger and fries for Obama; cheeseburger, fries and a milkshake for Biden -- comes after a week where they hit the road to highlight the need to increase investment in America's  infrastructure. Doing so, they said, will create jobs and relieve congestion.

We didn't know that infrastructure investment involved chipping in for cheeseburgers and fries. But who doesn't love fries?

Obama took four workers from the First Stree NE reconstruction project in Washington's NOMA neighborhood. The $9.1 million project ($6.9 million of which came from federal aid) is expected to be completed this week.

"If Congress does not act by the end of the summer, we could have hundreds of projects like this stop," the president told reporters. The White House also nicely tied in their push to increase the minimum wage, with Obama telling reporters that they chose Shake Shack because it has "great burgers and pays its employees more than 10 bucks an hour." Obama was a bit hoarse and has been nursing a cold.

Meredith Upchurch, who works on stormwater management for the District of Columbia, was one of the four people invited. She said she and her colleagues didn't know they were meeting with Obama and Biden until they got to Shake Shack.

"It was pretty much, 'okay, what are we going to talk about?'" she said in a phone interview. "We were assured that the president and vice president would have plenty of questions."

And they did, she said. As she ate a hamburger, she and her colleagues were peppered with queries about what they did on the project and how they thought infrastructure could be improved in Washington. Upchurch talked about the importance of cleaning up stormwater, and a colleague discussed LED lights.

"They both seemed knowledgeable about the topic and talked about it in other cities and states," she said. "That's really good to hear, that’s a topic that’s high on the mind."

So, are burgers the key to getting things done in D.C.? Who knows? At least four people got a (hopefully) free lunch out of the deal.

This post has been updated with Upchurch's remarks.