A Google car expert told us there's one thing that could seriously delay self-driving cars

The Department of Transportation wants cities to be smarter.

That's why it formed the Smart City Challenge, a contest that challenged cities to draw up plans showing how they would make their city smarter to integrate emerging technology like self-driving cars. The winning city will receive $40 million and will be announced this month.

And it's not just the DOT that thinks cities need to be smarter to prep for driverless cars.

Andrew Ng, chief scientists at Baidu, often referred to as the Chinese version of Google, wrote in Wired that it's necessary to make "modest changes to our infrastructure" to get autonomous cars on the road.

Ng has proposed changes like having construction workers guide traffic using wireless apps instead of hand signals.

But Brad Templeton, a consultant on Google's driverless car project, told Tech Insider that making cities smarter to support driverless cars is the wrong approach.

"You don't get to change the world, your car has to adapt to the world it's given," he said.

Why's that? Because addressing the problem from an infrastructure standpoint is bound to move at a "snail's pace" and isn't as useful as other methods, he said.

Templeton proposes taking advantage of a device people always have on them to make cities better prepared for driverless cars: cell phones. Rather than mold cities to prepare for driverless cars, it's better to collect enough data on people's movement so that cars understand their surroundings and traffic patterns.

Waze is just one example of an app that could be used for that very purpose, he said.

Not only is this a faster approach, but also a more comprehensive one as phones collect so much data.

"When you give software people that challenge, they rise to it," Templeton said. "When you give infrastructure the problem, they form a committee."

A division under Google's parent company Alphabet is taking the Templeton approach.

Called Sidewalk Labs, the division has teamed up with the Department of Transportation to aggregate data pulled from Waze, Google Maps, and sensors on the roads to understand transportation patterns to make it easier for driverless cars to navigate.

Toyota is also using data from customers' vehicles to map routes driverless cars can use to navigate safely. Companies like Audi, Daimler, BMW, and Uber are also mapping routes.

So even if we're channeling resources into making cities smarter for driverless cars, many companies are already tackling the issue using software.