We explore various options for constructing Hoosier roadways
As we’ve extensively detailed for you, Indiana’s roads couldn’t be more of a hot topic for legislators right now.
Shortly after the conclusion of the 2024 legislative session, House Committee on Roads and Transportation Chair Jim Pressel (R) of Rolling Prairie went as far as to muse that road funding has “consumed his life.”
While new ideas and improvements are ever-present in transportation, Hoosier or otherwise, one thing has stayed in stasis: asphalt and concrete roads.
When we think of roads of the past, we envision cobblestones and dirt, horses and buggies. Using asphalt and concrete instead makes sense as the natural evolution of road materials that support the ubiquity of motor vehicles.
However . . . in truth, our roads fundamentally haven’t changed since the Roman Empire. We still utilize the same basic formula: The surface layer of pavement is smoothed over chunky layers of granular materials, thereby diffusing traffic load strain to the underlying soil.
The adage “Well, if it ain’t broke, don’t fix it” would be breezily applicable here . . . but Indiana’s roads are indeed broken. The Governor’s Next Level Roads plan has recognized the dilemma, and the Crossroads of America already faces an estimated $1 billion annual shortfall in revenue needed to maintain and repair state and local roads. That’s without mentioning the billions INDOT already spends on maintenance of existing roadways (an inventory that increases almost daily).
That’s not all. The overall costs of road repair can be much higher than the base figures.
“Traffic jams caused by infrastructure repairs waste four billion hours and three billion gallons of gas [yearly] … due to insufficient knowledge and understanding of concrete’s strength levels,” Purdue College of Civil Engineering Associate Dean of Faculty Luna Lu tells your favorite transportation newsletter.
Dr. Lu, the Reilly Professor in the Lyles School of Civil Engineering, is specifically concerned about the unpredictability of concrete rest times: “The concrete may go through premature failure, leading to frequent repairing.”
Where Do We Go From Here?
So, okay – concrete and asphalt aren’t perfect . . . but major industry players are starting to reimagine how we build our roads. Heritage Construction + Materials CEO Geoff Dillon has extolled the virtues of asphalt for years, deeming it “reliable, durable, cost-effective, and sustainable.” However, he also believes that asphalt will be combined with other materials in the future, stating that “there are situations where [a combination] would make for [a] more appropriate solution.”
A report by HG Ventures, a partner of Heritage, states that asphalt is “already one of the world’s most recycled materials . . . advances in materials science could see the amount of recycled materials increase over time.” Some regulations currently constrain permissible amounts of recycled asphalt pavement or recycled concrete aggregates. This may have to change if the National Asphalt Pavement Association wants to meet its goal of net zero carbon emissions during asphalt production and construction by 2050, considering that concrete production alone contributes to 8.0% of global CO2 emissions, according to the World Wildlife Foundation.
Recycled Roads
Considering the environmental impact and longevity of concrete and asphalt, researchers are eyeing integrating one of humanity’s most copious byproducts into the mix. A May 2023 report from the World Bank suggests that using plastic waste as a modifier for asphalt is feasible.
In 2020, California repaved a section of Highway 162 using only recycled asphalt pavement and liquid plastic sourced from single-use, plastic bottles. On that issue, California Sen. Ben Hueso (D-CA) asserts that “using waste plastic that was otherwise destined for a landfill will not only reduce the cost of road repair and construction but also increase the strength and durability of our roads.”
To Sen. Hueso’s point, the plastic section of Highway 162 yields stronger results in durability and longevity tests than traditional asphalt pavement. Another company, KWS, a subsidiary of international construction company VolkerWessels, explores modular plastic roads that “fit together like children’s LEGO bricks,” per an HG Ventures report. These “jigsaw” roads are being trialed on bicycle paths in the Netherlands.
With Indiana’s expensive and expansive infrastructure, innovative methods to lengthen roads’ lifespans may be considered soon.
Roads Repairing Themselves
Diversifying road materials isn’t the only solution. The World Economic Forum labels “self-healing” road materials as one of the top emerging technologies globally.
While much of this concept is still in the research phase, concrete possibilities (get it?) are coalescing. In 2013, the University of Bath, the University of Cardiff, and the University of Cambridge abroad started a collaboration to create a concrete mix that contains bacteria housed in microcapsules. These capsules activate when water enters a crack in the concrete, allowing the bacteria to feed and produce limestone to seal the crack.
Researchers estimate this mix could reduce repair costs by 50% over the road’s lifetime. Magnetite iron ore is another option. University of Minnesota researchers are converting the ore into bitumen, a construction material that can “readily absorb microwaves and heat very quickly.”
With bitumen, pothole repairs in cold weather are substantially speedier. Asphalt hardens slowly in chillier temps, so it’s not uncommon for winter potholes to be filled with gravel or patches until warmer weather arrives – allowing for additional damage in the interim.
Robotic Roads
The term “electrified roads” doesn’t just refer to electric vehicle infrastructure – we’re seeing technology and automation embedded within the mix itself.
“Smart pavement” can sense and respond to changes in its environment, allowing it to communicate with road users and other devices. The sensors are embedded into fresh concrete, and can measure the concrete’s strength levels in real time, conveying when highway pavement is strong enough for traffic – and then grab information on traffic volume, speed, weather conditions, and more, then relay that information to the intended parties. Dr. Lu’s lab at Purdue develops and furthers these smart road technologies. In addition to her academic and research expertise, Lu is the founder and CEO of Wavelogix, a Purdue-rooted startup that developed the REBEL concrete strength sensing system.
“We look at how we can address problems in infrastructure using materials and sensors that harness artificial intelligence and big data,” she explains. “The idea is to make infrastructure adaptive, sustainable, and resilient.” The Purdue professor also refers to her work as “making concrete talk.”
If this sounds like a scrapped concept from I, Robot, let us clarify that this isn’t technology for the distant future – it’s already happening.
In 2019, Dr. Lu collaborated with the Indiana Department of Transportation to embed her sensors into three Indiana highways: I-465 near Indianapolis, I-70 near Plainfield, and I-74
near Batesville. Dr. Lu’s team is collaborating with the Federal Highway Administration to install and operate more sensors on highways nationwide.
As emerging alternatives for road construction become viable, consider their integration into Hoosier roads imminent.
Indeed, Dr. Lu is slated to step down from her deanship on January 1 as she becomes vice president of the Office of Industry Partnerships. OIP facilitates collaboration between businesses and Purdue faculty, staff, and students to create mutually beneficial relationships that drive innovation, research and economic impact. OIP also collaborates closely with the Purdue Research Foundation to refer industry partners for economic development and intellectual property and startups. OIP further serves as a one-stop shop, providing internal support to all units, and acting as a concierge for external industry partners . . . so expect more from Dr. Lu and her shop on road matters given her specialized expertise and new role.
“Indiana is a leader in digital adoption [in transportation],” Conexus Indiana Vice President Bryce Carpenter tells your favorite transportation newsletter. “Indiana is [also the] number one state in pass-through highways.” This makes Indiana’s road health vital to the nation’s economy and supply chains – Crossroads of America indeed.
Picture this: One day, we may live in a world where no one brings up potholes when discussing Indiana road funding (or municipal elections!).
. . . Well, one can dream.