Preparing for a world of 9 billion people, Shell Oil Co. president, Marvin Odum, said this week at the Aspen Ideas Festival, "is all about smart urbanization."

In many ways, smart urbanization is all about smart transportation, and, as U.S. Transportation Secretary Ray LaHood said in panel to discuss "How Can We Create Smart Transportation" at the Aspen Ideas Festival, "smart transportation is alternative transportation."

In recent years, the United States' ranking on infrastructure fell to 24th place worldwide, according to the World Economic Forum's Global Competitiveness Report. To meet the demands of our growing population in a way both economically viable and environmentally sustainable, we will have to get our current infrastructure back up to snuff. But we will also have to invest in alternative forms of transportation and in the groundbreaking technologies that will, over time, revolutionize the way we get around.

"There's no stopping high-speed rail," said LaHood, setting a goal of getting 80 percent of the country connected by passenger trains in the next 25 years. LaHood said the Obama administration invested $11 billion in building high-speed rail networks since taking office. 

Richard Florida, author of The Rise of the Creative Class, echoed his sentiment. "If we're going to build functioning mega-regions, it's just a no-brainer: We have to build high-speed rail systems," he said.

Yet passenger trains will not be a cure-all solution. With the widening of the Panama Canal, we will have to build new port facilities and improve old ones to accommodate the changes in freight shipping. In our cities, we will have to find ways for public transit riders to complete the "last mile" between the mass transit station and their destination. 

This will mean investments in making cities more bikeable and walkable. We will also have to improve and maintain our legacy network of roads, bridges and interstate freeways upon which the economic success of this country accelerated over the past half a century.

In our world of finite resources, the two competing visions of investing in the roads and bridges of the present or investing in the trains and heretofore-unknown technologies of the future are sometimes at odds. This controversy was on display at the Smart Transportation panel, as audience members and panelists engaged in a spirited debate over how the future of our transportation infrastructure ought to look.

Some in the audience questioned the wisdom of investing in things like high-speed rail, city-walkability, and public transit systems while the country's roads and bridges a pass into disrepair. Others asked why more had not been done, calling for a Manhattan Project-style national effort to overhaul the country's old transportation systems and develop wholly new ones, such as self-driving cars.

But there are places where these two purposes meet. Efforts to install natural gas pumps and electric car re-charging stations at locations around the country will upgrade our car culture while reducing environmental impacts over time. 

Research into developing "autonomous vehicles," or cars that drive themselves by communicating with other cars, could turn our roads into mass-transit systems, as connected cars move safely and efficiently down the road in unison while the person-formerly-known-as-the-driver is freed to, for instance, send a text message without risking an accident.

Upgrading our old systems while developing new ones will be a massive undertaking but it is one for which this country is prepared. "We always do big things. That's what America's been known for," said LaHood. "And we don't let the naysayers and those who have no vision stand in the way."