In a recent American Society of Civil Engineers (ASCE) article, Tom Fisher, Professor-College of Design-University of Minnesota and Director-Minnesota Design Center (MDC)-College of Design-University of Minnesota, expressed his ideas of the future of roadways saying he imagines a dramatically different streetscape than the one most people drive on today … mainly that the people won’t be doing the driving! Instead, Fisher sees a future in which autonomous vehicles (AVs) briefly share the roads with human-driven vehicles at first, then inevitably replace those traditional cars and trucks entirely. As a result of that self-driving scenario, the road itself will also change, because AVs are, simply put, better drivers—or at least more precise drivers.
When humans drive cars and trucks, they tend to “wander across the road surface”, shifting a little to the right or left within their lane as they travel along, Fisher said. But AVs, guided by GPS and other navigational aids, follow and maintain a much more precise path, meaning that each AV will drive over the same parts of road surfaces on every trip. Unfortunately, such precision can lead to repetitive wear damage to a road surface, especially on gravel and asphalt roads, Fisher noted. This was evident in a 2018 pilot project conducted by the Minnesota Department of Transportation: Fisher explained that they witnessed an autonomous bus that left visible ruts in the roads after driving on it, caused by the repetitive wheel path tracks of the bus due to following a programmed route.
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A multidisciplinary team at the University of Minnesota—including the Minnesota Design Center, the College of Science and Engineering, and the School of Public Affairs—is researching how shared AVs will affect community health, equity, livability, and prosperity. This research is being funded by a 3-year, $1.75 million grant from the National Science Foundation as part of the NSF’s “Smart & Connected Communities grant program”.
Reviewing the results from the MnDOT autonomous bus pilot STUDY:
• Fisher and his colleagues began to ask themselves: “What would a road be like that could handle the repetitive wear of (autonomous) vehicles?”
Their conclusion:
• AVs will require a different type of street, perhaps one that features tracks of reinforced-concrete grade beams for the AVs to drive along.
– Use of such grade beams would enable the road surface between and around the beams to become pervious
– Example: instead of constructing continuously paved roads with curb-and-gutter storm sewer systems, necessary today, the future streets for AVs could replace impervious asphalt with permeable concrete pavers or low ground-cover vegetation, such as sedum.
– By replacing the existing stormwater system with underground stormwater retention basins or adjacent bioswales, “it would allow us to capture and not only retain stormwater but also recharge aquifers” as the water percolates down through the roadbed, Fisher said.
– For a 36,000 sq-ft road surface, which today is entirely impervious, the new AV street design could feature as much as 27,000 sq ft of permeable surfaces, with only about 9,000 sq ft of impervious concrete for the grade beams, Fisher added.
• Connections to adjoining tracks on the side of the road—in case a vehicle needs to pull off to pick up, drop off passengers, or allow other vehicles to pass.
• Additional benefits would derive from the fact that AVs are expected to generate much greater throughput, meaning “you won’t need as many lanes to move to the same number of people,” Fisher noted:
– 4-lane roads today could need just 2 lanes in the future, narrower—perhaps just 8-ft wide lanes compared with 11- or 12-ft of current streets, Fisher said.
– Space no longer needed for road surfaces could then be reallocated to more green space—trees and plantings
– Dramatically help with carbon sequestration and reduce the urban heat island effect created by today’s roads
• Overhead streetlights could disappear, reducing the effects of light pollution in cities and suburbs, since the roadway itself would no longer need to be illuminated.
– Bollards along the road could simply illuminate the adjoining sidewalk and bike paths.
• AVs are eventually shared rather than individually owned, as Fisher expects—as part of mobility-as-a-service operations—then many existing parking areas could be converted to other uses as well.
– Fisher noted: As much as 30% of urban and suburban land is currently dedicated to parking, so all that land could be freed up for alternative uses.
• Fisher expects that although AVs will need to share the road with human-driven vehicles for a certain period, driving itself will eventually be banned in urban and suburban areas—relegated only to the countryside—compared this scenario to 100 years ago when cars and trucks began to replace horses.
– “We discovered that having horses and cars on the road at the same time doesn’t work very well, so today we relegate horses to the countryside, and you can’t ride a horse down a city or suburban street. In the same way, within a couple decades, you won’t be able to drive down a city or suburban street,” Fisher said.
– Fisher predicts: As driving a car becomes less common, it will also become far more expensive because of the rising cost of car insurance as the insurable pool of high-risk drivers shrinks. Eventually, driving could become a hobby just for rich people—and even they will likely need to take AVs to get out to places in the country where they will store their cars, he adds.
The possibilities presented by AVs & the redesign of roads provide “a huge opportunity for our civil engineering community to envision a different kind of infrastructure that is more environmentally friendly & much safer,” Fisher said.
Moving forward, Fisher and his colleagues are working with MnDOT to develop a pilot project to test their proposed redesign of roads for AVs at various sites within the state, including Grand Rapids and Rochester.
An online publication called Future Streets, summarizing the findings and proposals, is expected to be released later this year.
“…With a decrease in oil production we will see less asphalt available. Moving to using concrete pavers or plastics will occur.” —Ken Davlin, PE
For the ASCE online E-News article titled “How autonomous vehicles will change road designs” please go to: https://source.asce.org/how-autonomous-vehicles-will-change-road-designs/