Several trends are converging to redesign the nation's transportation landscape, increasing the stakes for state and local government policymakers looking to navigate the familiar issues of ever-increasing traffic congestion and steady declines in the traditional sources for funding highway construction, maintenance and repairs.

Foremost among those trends is the advent of autonomous vehicles -- the so-called "self-driving cars" that have excited the imaginations of the public and transportation professionals alike. Technology-driven vehicle innovations once predicted to be 15 to 20 years away now look to be just one to five years from reaching consumers. Industry analysts estimate that half the vehicles sold in the United States this year will have some form of connectivity with roadside systems and other vehicles, and many are predicting that we will see the first fully autonomous vehicles within the next five years, with mass adoption a decade or two later.

These advances will have a profound impact on transportation planning and fundamentally change the way we move around. Using image sensing, global positioning and computer vision systems, autonomous vehicles will be able to "sense" their surroundings. They will have the ability to collect, share and act on enormous amounts of data, including information from roadside systems about real-time traffic conditions, and at the same time give out data about their speed and lane movement. They will be able to communicate with cars around them, which means improved traffic flow and safety.

While concrete and asphalt have long been the simplest solutions to easing congestion or meeting the need for extra road capacity, these technological advances have created new opportunities for addressing these challenges. What that means is that we are going to have to figure out how to begin developing the smart highway.

Policymakers looking for blueprints on designing smart highways should look no further than the states and localities that are taking the lead. What they have in common is a deliberately cautious approach based on a couple of important principles: They are collaborating with independent researchers and industry advisers to develop a sound regulatory framework, and they are developing public-private partnerships to conduct careful, phased testing and refining of the highway infrastructure these smart vehicles will require to operate safely and effectively.

Already, six states and the District of Columbia have passed legislation aimed at creating an orderly and managed process for testing and introducing autonomous-vehicle traffic in their jurisdictions, according to data collected by the National Conference of State Legislatures.

These regulatory frameworks include requirements for permitted uses, specific locations, certifications for safety, and operations developed with scientific and technical input.

California recently began issuing permits to automakers and Google for testing of autonomous vehicles on that state's roads and highways. In Virginia, Gov. Terry McAuliffe recently announced an innovative public-private partnership for research and testing of autonomous vehicles in a high-traffic corridor around Washington, D.C., led by Virginia Tech's Transportation Institute, the Virginia Department of Transportation, the Virginia Department of Motor Vehicles and my company, Transurban.

The project will develop a test roadbed on a heavily used set of highways that integrates a wide range of technologies, from high-definition mapping capabilities to real-time traffic information to vehicle connectivity. Importantly, the Virginia test zone features complex curves and carries traffic operating at higher speeds. This is a tremendous opportunity to test automated vehicles in an ideal, real-world environment.

Governments and the private sector are showing a willingness to be creative and collaborative to devise innovative, market-proven solutions to meet our transportation challenges. As advanced technologies such as autonomous vehicles continue to develop, look for even more of these future-focused demonstration projects to test and refine the policies and technologies that will serve as models for the nation's smart highways.