Why Are Highways Always Under Construction? [Thoughts After Dark]

Thoughts After Dark answers the questions you have in the final moments before drifting off to sleep when a simple Google search turns into an hour-long exploration into how things are made and how they work. Your random late-night questions are answered here — even the ones you didn’t know you had.

Driving toward my hometown for the first time in a few years, I point out the window, signaling my partner to look. “I can’t believe this portion of the highway is finally done,” I say, laughing in astonishment. Growing up in Kansas, I drove down Old Highway 56 too many times to count, but this was the first time it wasn’t under construction.

It’s rare to drive down a long stretch of highway and not see bright orange traffic cones, “work zone ahead” signs, or heavy machinery moving gravel. But why are highways always under construction?

While construction slowdowns can be frustrating, there’s a reason for their frequency.

What Materials Are Used to Build Highways?

The first United States highway, coined the National Road, began construction in 1811 and eventually ran 820 miles through Illinois, Indiana, Maryland, Ohio, Pennsylvania, and West Virginia. The highway was built with rocks and gravel broken by hand and laid in trenches.

With today’s heavy vehicle loads and traffic, this construction method doesn’t cut it. In 2023, highways are built using distinct materials to ensure durability. The most common types of road construction materials are:

• Soil: Provides the flat base that supports road structure
• Aggregate: Used for granular bases, sub-bases, and as part of cement concrete
• Asphalt: Used in road construction because it’s 100% recyclable and cost-effective
• Concrete: Used to extend the service life of roads but is more difficult to repair than asphalt

Why Are Highways Always Under Construction?

In the United States, American drivers cover more than three trillion miles each year — which is enough to take around 5,000 trips to the moon and back. This heavy traffic takes a toll on highways, which is why busy cities seem to be hit with the most construction backups.

But it’s actually not vehicles doing the most damage to roadways; it’s the elements. Here are the main reasons highways are frequently under construction.

1. Water

In the winter, snow constantly freezes and thaws, which is a vicious cycle for roads made of tarmac and asphalt.

When a roadway surface cracks, which occurs over time due to heavy pressure on roads, water can seep in and weaken the base layer, causing depressions. When the base layer of a road is damaged, it’s more vulnerable to cracks and potholes until it’s repaved.

2. Sunlight

Most highways today use asphalt, which is a binder of rock, aggregate, and sand that creates a flat surface because it’s easier to repair than concrete. However, ultraviolet rays can dissolve the binder, creating a gravel mess and destroying roads.

3. Oxidation

You can always tell when a fresh patch of the highway is put down because it’s darker than the surrounding roadway. That’s because the road surface gradually becomes lighter with exposure to oxygen.

However, oxidation slowly breaks down the asphalt layer of the road and makes it more susceptible to cracking under heavy loads.

4. Leaking Oil

Small amounts of leaked oil aren’t usually an issue, but the longer oil sits and builds up, the more likely there will be asphalt breakups.

5. Aging and Improper Infrastructure

Some parts of highways are centuries old and came before the United States became a country. On top of that, companies often don’t coordinate their plans to cut into asphalt to set up telecommunications, gas, or electricity networks — which can damage roadways if done improperly.

Luckily, the $1.2 trillion Infrastructure Investment and Jobs Act, representing $550 billion worth of increased infrastructure investment, has set out to improve the United States’ aging infrastructure. As part of the bill, $110 billion is going toward improving roads, bridges, and highways.

The States with the Most Roadway Construction

When you’re used to being held up or late due to construction, it can feel like you must live in the state with the most roadwork happening. You would be correct if you live in New York, Texas, or California.

New York

In the Big Apple, nearly every major downtown street is under reconstruction. In the long run, this is a good thing for drivers, but it can be a frustrating experience while it’s happening. There’s currently around $14 million in federal funding in play to complete road construction to remove congestion on roads across New York.

The state received $13.6 billion via the infrastructure bill to improve roadways and bridges.

Texas

Last year in Texas, residents raced to the state’s Department of Transportation to voice their concerns about new highway expansions that would displace residents, businesses, and schools. Residents complained that the state continues to widen highways, but its mass focus on cars makes it difficult to take other forms of transportation like buses or trains.

“It’s just plain Jane boring lanes, more and more lanes,” said Fabian Ramirez, a structural engineer whose property in Houston’s Northside district is set to be demolished amid the $9 billion project to widen and realign the city’s highways. “There’s no train, there’s no bus, there’s no anything that supports mass transportation. It doesn’t exist.”

The state received $35 billion via the infrastructure bill to improve roadways and bridges.

California

If you live in or have visited California, traffic jams are part of the process of getting from point A to point B. In turn, the Golden State received the largest share of funding from the infrastructure bill at $45.5 billion to improve roadways and bridges.

Fun fact: the states with the best highway systems are North Dakota, Virginia, Missouri, Kentucky, and North Carolina.

How to Repair Highways

Roadways are frequently under construction, but workers don’t always use the same method to fix them. Depending on the damage and size, these are the most common repair methods, according to Civil Engineering Portal:

• Sealing with Coating: A method that uses crack-filling materials (asphalt emulsions, asphalt cement, and fiberized asphalt) to restore the look of a road and its durability
• Patching: A method that is used to fill smaller holes or cracks in the pavement to avoid further degradation
• Full Repair: By far the most effective but time-consuming, this method resurfaces worn-out asphalt with new asphalt
• Cold Method: A method using a technique of laying a cold-lay material into a pothole or portion of a damaged road layer by layer and compacting it down, resulting in a more durable surface
• Throw and Roll Method: A method for putting asphalt patch materials into a pothole and driving over it with a tractor, bulldozer, or huge truck
• Resurfacing: By far the most environmentally friendly, this method removes all asphalt to be crushed into smaller gravel-like pieces to make a new and stronger aggregate for reuse

4 Innovations in Roadway Upkeep

While sitting in standstill traffic in downtown Chicago recently, I impatiently asked my partner why we don’t just make all highways out of metal so they last longer. He reminded me of the icy Windy City winters. “Imagine cars driving on slippery metal in the midst of that,” he laughed.

While highways likely won’t be made of metal any time soon for several reasons, the construction sector is innovating. Like many other industries, it’s adopting new technology to boost productivity, automate tasks, and make roadways more durable.

1. Autonomous and Electric Vehicles

Over the last few years, the United States has ramped up its investments in electric and autonomous vehicles. In fact, by 2030, the U.S. aims to have 50% of all vehicles sold each year be zero-emission. Additionally, by 2035, 15% of light vehicles sold are expected to be fully autonomous.

This doesn’t just impact sustainability — autonomous vehicles also enable narrower highway lanes. This means instead of construction being done to widen or build new lanes, four-lane roads could eventually be up to 4.0 meters narrower than they are today.

2. Automation

Most construction work requires manual labor, but automation is promising to improve productivity. This will be especially beneficial when it comes to the surveying of a site.

According to McKinsey & Company, initial surveying could be automated using lidar technology to reduce time and cost: “Data from multiple sources could be fed into a digital representation of the physical asset — known as a digital twin. Such digital models allow contractors to visualize the entire lifecycle of a road, optimizing its performance.”

In February, robotics developer Boston Dynamics demonstrated a robot conquering a construction site and moving objects. While it will be a while before the Atlas actually takes on construction or manufacturing tasks completely solo, the company says the robot was “a sneak peek at where the field is going.”

3. More Durable Materials

Modern roadways are turning to new materials to make longer-lasting highways. While asphalt mixtures are typically created with stone, sand, or gravel, Missouri researchers discovered that plastic waste is a more durable substitute for aggregate.

Plastic items such as grocery bags and straws are chemically similar to asphalt because they both come from crude oil. To put it to the test, University of Missouri engineers, chemical company Dow, and the state’s Department of Transportation used a plastic-asphalt mixture on a two-mile section in Columbia, Missouri, that services about 36,000 vehicles every single day.

“I saw that in India, China and some other places in Europe had attempted to make waste plastic recycling and asphalt with varied success,” said Bill Buttlar, the Glen Barton Chair in Flexible Pavements in the university’s Department of Civil and Environmental Engineering. “And so, our challenge was to figure out how to make it work better and pass the tough standards that we have in the United States.”

By paving four lane miles in Missouri, the team repurposed 30,000 pounds of plastic waste, equivalent to about three million shopping bags.

4. Self-Healing Concrete

As the number of drivers on roadways increases, highways aren’t lasting as long as they once did. But self-healing, smart concrete could fix that.

Unlike traditional forms of asphalt and cement used for road construction, smart cement has self-healing properties and can adjust to various temperatures. Self-healing concrete doesn’t just repair itself but can even warn engineers of new cracks, stress or strain, and high-traffic areas.

The Defense Advanced Research Projects Agency (DARPA) recently announced its development of BRACE, a self-healing concrete for military naval piers, missile silos, and airfields.

More Construction Insights

• As Construction Demands Evolve, Industrial Project Activity Remains Robust
• DARPA to Repair Military Runways with Self-Healing Concrete
• New Smart Cement Has Self-Sensing, Self-Healing Properties
• Boston Dynamics’ Dancing Robot Conquers a Construction Site
• Michigan Begins Construction on "Digital” Highway

Read more from Thoughts After Dark. 

Image Credit: J.D.S / Shutterstock.com