Here at Ars, we like thinking about the future. And some of the biggest problems we’ll have to solve in the future are related to transportation. The population of the US is increasing, fossil fuel consumption must be cut or climate will change more dramatically than it already is, and autonomy is coming to vehicles. So it’s worth asking our presidential candidates their views on transportation policy. After all, the policies of the next four years could impact how automakers implement autonomous systems, whether large train systems will be built (hello, Hyperloop?), and how quickly electric vehicles will be adopted.

Unfortunately, although Ars reached out to Hillary Clinton, Donald Trump, Gary Johnson, and Jill Stein’s campaigns, not one of the candidates’ teams got back to us. That left us with statements on the candidates’ websites and comments they made during debates and interviews earlier this year.

Clinton

Clinton’s policies are by far the most thorough, although there are still gaps in her plan that leave room for questions.

The Democratic Party nominee says she would set aside $275 billion for infrastructure, $25 billion of which would be used to create an infrastructure bank that would allow the government to leverage another $225 billion in loans and credit, which would be used for building even more infrastructure.

The former secretary of state added that she’d raise the money for this endeavor by overhauling how businesses that keep assets abroad get taxed on those assets. Clinton also says she'll renew and expand the Build American Bonds program that President Barack Obama started in 2009 to fund some of her infrastructure projects.

But figuring how much of this huge infrastructure outlay would go toward building trains or upgrading networks for automotive and air fleets is difficult. The plan Clinton articulates on her website groups all federal infrastructure projects together and doesn’t detail how much, for example, she’d like to devote to building roads better equipped for smart vehicles versus how much she’d like to devote to less-transportation-minded endeavors, like building more broadband infrastructure which Ars’ Jon Brodkin covered in a separate piece.

But among the goals listed on her website, Secretary Clinton says she wants to use at least part of that $275 billion to create roads that can talk to autonomous vehicles. Clinton’s website doesn’t get more specific than that, but one idea that’s been floated involves building wireless beacons at intersections where the glare of the sun makes traffic lights difficult to see. Automakers could then equip their cars so that the vehicles will know automatically if the light is green or red.

The Democratic candidate also said she’d use some of the infrastructure money to build “advanced fueling stations,” as well as equip roads with “sensors capable of alerting drivers to a dangerous icy patch a mile ahead.” She promised to also use some of those infrastructure billions to “provide more funding for basic research in transportation technology,” especially tackling problems that are “too far in the future for private industry to address."

Clinton’s campaign claims that this funding will result in fewer accidents and less traffic due to the introduction of “vehicles that can sense and communicate with one another.” The funding would also theoretically reduce pollution after “more efficient and effective parking management systems,” are introduced.

In her official statement, Clinton didn’t mention California’s bungled High Speed Rail project, and neither did her campaign share any opinion on the likelihood of Elon Musk’s Hyperloop idea making it from the hands of turmoil-ridden private companies to the real world. But she did offer some salient details on improving aviation technology. The Clinton campaign writes that World War II-era air traffic control systems need to be chucked in favor of “NextGen,” a satellite- (rather than radar-) based system that has been in the works since 2007. The system is projected to ultimately cost the Federal Aviation Administration $17 billion in total (including funds that have already been spent), as well as $15 billion in private sector costs—that is, getting airlines to upgrade their equipment to work with the new system.

“These efforts have fallen chronically behind schedule and well short of expectations,” Clinton’s campaign writes. “Clinton will get this crucial program back on track and ensure that it is managed effectively and with accountability. These changes will save air travelers and airlines an estimated $100 billion in avoided delays over the next 15 years.”

Despite campaign promises, getting the money to fund all this would be a real challenge. The US has traditionally funded transportation infrastructure with the Highway Trust Fund, financed by the federal gas tax, which hasn’t been raised in decades. Republicans would like to see the gas tax abolished and infrastructure spending tossed back to the states. The Obama Administration has fought to increase funds for infrastructure spending to no avail. If Congress’ demographics don’t change dramatically, Clinton could have as difficult a time as Obama did getting tax hikes for infrastructure spending approved.

Trump

Trump’s written and stated plans, compared to Clinton, are much, much more vague, but also more surprising, as they break significantly with the 2016 platform put forth by the Republican party. His campaign, like Clinton’s, did not respond to Ars’ request for comment.

Throughout the summer, the businessman told reporters that he would more than double Clinton’s proposed spending on infrastructure, bringing the cost of his plan into the half-a-trillion-dollars range.

But Trump’s plan to fund all this spending hasn’t been adequately articulated, except for in a couple of offhand comments he’s made on the campaign trial. According to The Hill, over the summer Trump told Fox Business Network’s Stuart Varney that he’d set up a fund to finance his infrastructure projects, offering only that “people, investors,” would be the primary contributors to that fund.

“We’ll get a fund, we’ll make a phenomenal deal with the low interest rates and rebuild our infrastructure,” Trump told Varney. “The citizens would put money into the fund... and it will be a great investment, and it’s going to put a lot of people to work.” The Republican candidate explained that the money for the fund would come from selling infrastructure bonds.

No matter where the money comes from, Trump’s ideas reflect a break from his party. Typical Republicans try to kill most federal infrastructure spending initiatives that come through Congress in favor of letting states fund transportation and infrastructure as they wish. The Washington Post wrote that when federal GOP lawmakers put together their party’s platform, it called for a significant reduction in how the Highway Trust Fund is funded, including a repeal of gas taxes. The GOP wrote:

We propose to remove from the Highway Trust Fund programs that should not be the business of the federal government. More than a quarter of the Fund’s spending is diverted from its original purpose. One fifth of its funds are spent on mass transit, an inherently local affair that serves only a small portion of the population, concentrated in six big cities. Additional funds are used for bike-share programs, sidewalks, recreational trails, landscaping, and historical renovations.

Now, Trump doesn’t seem to be against cutting taxes that feed the Highway Trust Fund—he said wants to subsidize all his planned building by selling infrastructure bonds, after all. But the Republican candidate has repeatedly called for a national effort to repair roads and bridges beyond what many Republicans would deem kosher. According to The Hill, Trump made a promise in June to “build the greatest infrastructure on the planet Earth—the roads and railways and airports of tomorrow.” Trump at the time also called for the rebuilding of “dilapidated airports,” a sentiment he echoed in the first presidential debate at Hofstra College on Sept. 26.

Outside of building massive airports, road networks, and train stations, Trump’s campaign website doesn’t directly target any policies regarding future transportation. He’s called for a general “temporary pause on new regulations and a review of previous regulations to see which need to be scrapped,” which could, among many other things, impact the way the federal government regulates automakers or the shipping industry or any number of transportation-related government endeavors.

The Republican candidate also said he would not support the Trans-Pacific Partnership (TPP)—a multi-national trade agreement that covers everything from intellectual property to tariffs in trade between countries. Trump’s website specifically called out the auto industry as a potential victim of the TPP, saying the trade deal “will hammer the car industry because it does not resolve, among other things, the substantial non-tariff barriers to US cars being sold in Japan and other countries—including currency manipulation, excess supply, and closed dealerships."