Heavier Vehicles Need Stronger Guardrails
Our infrastructure was not designed for what most Americans drive today.
Slate (“A 7,000-Pound Car Smashed Through a Guardrail. That’s Bad News for All of Us.“):
It’s a nightmare situation on a highway: Your car hits a patch of ice and starts to skid. Unable to regain control, you panic as you veer toward the roadway’s edge.
In emergencies like this, guardrails provide a failsafe. As explained in a federal memo, a guardrail will “deflect a vehicle back to the roadway [or] slow the vehicle down to a complete stop.” Your car will probably be damaged, but guardrails can prevent something much worse.
But some modern vehicles can instead smash through these guardrails, new research demonstrates, sending their passengers hurtling toward a ditch, cliff, or whatever is on the other side. The problem is that thousands of miles of guardrails installed alongside American highways were designed decades ago, when vehicles were much lighter than the behemoths that increasingly dominate the U.S. car market.
These pieces would be more useful without the sneering language. While I get that large vehicles have negative externalities, there are all manner of reasons why they’re becoming increasingly popular. Including the fact that their prevalence puts those in smaller vehicles at a disadvantage on the road. What makes sense in Boston doesn’t necessarily make sense in Bismark or even Birmingham.
Regardless, the facts are what they are:
And cars are only getting heavier: Bulkier electrified versions of big cars are poised to arrive in the years ahead. The risk of huge vehicles tearing through guardrails is yet another reason to expect American car bloat to augur an expensive, and dangerous, roadway future.
Again, “bloat” inserts sneering judgment into what would otherwise be a scientific analysis.
The new study comes from the University of Nebraska, which received funding from the U.S. Army to examine the impact of electric vehicles on guardrails. The university is a natural location for such research; its Midwest Roadside Safety Facility designed and tested the metal barriers known as the Midwest Guardrail System that are a familiar sight along American highways. The MGS is a beam with a dip running horizontally in the middle—if you think of a guardrail, you’re probably picturing one. “It’s the most frequently used guardrail system, because it’s the cheapest to install and maintain,” said University of Nebraska engineering professor Cody Stolle, noting that all 50 states use it.
The current version of MGS was developed to withstand cars weighing a maximum of 5,000 pounds, but many of today’s SUVs and trucks exceed that threshold. A Cadillac Escalade, for instance, now weighs over 6,200 pounds, and the latest model of the Ford F-150, the most popular vehicle in America, can tip the scales at almost 5,700 pounds. You don’t really want to hit a guardrail with a vehicle like that, but electrification can make things even dicier. Electric cars often weigh around 30 percent more than a gas-powered counterpart, because big vehicles require enormous batteries to propel them hundreds of miles between charges. The goliath-like GMC Hummer EV weighs a staggering 9,083 pounds, 2 tons more than a gas-guzzling H3.
Again with the social commentary. While I don’t get the attraction of the Hummer, it’s not even a particularly large vehicle compared to a full-sized pickup truck or SUV. But, yes, the electric version is staggeringly heavy.
In their study, the University of Nebraska researchers wanted to see whether guardrails can withstand a collision with a big, modern EV. Their answer: No.
Last October, the researchers directed a passengerless 2022 Rivian R1T truck weighing around 7,000 pounds toward an MGS guardrail at 62 mph and a 25-degree angle, reflecting common highway crash conditions. The Rivian demolished the guardrail, passing through it before striking a concrete barrier that the researchers had installed as a backstop.
The silver lining, Stolle told me, was that the Rivian seemed capable of protecting passengers in that test. “The damage to the interior of the vehicle was very low,” he said, “and the occupant risk in that scenario would not be cause for alarm.” But he noted that in the real world, a guardrail is much more likely to be placed next to a steep dropoff than a concrete barrier. If a car penetrates a guardrail and tumbles down an incline, passengers would face far greater danger.
Hitting a guardrail at 62mph is definitely not a good idea. Doing so in a particularly heavy vehicle, apparently, even more so. Because physics.
It’s worth highlighting that this study isn’t really about the merits of EVs. After all, you can buy an EV that weighs less than 5,000 pounds. You just can’t electrify your favorite already-large car—or even buy a hulking gas-powered car—and expect guardrails to work as intended. “Weight is a universal problem; it is not unique to electric vehicles,” Stolle said. “We have similar concerns about the compatibility of the biggest gas-powered cars with our guardrail system.” The 6,700-pound Chevrolet Silverado 1500 already weighs too much, based on the result from this research, and the 8,500-pound Silverado EV weighs even more.
A caveat: This is only one study, using a single truck. Still, its implications are troubling, to say the least. As the average American car grows larger, today’s guardrails could fail in more crashes, creating a new highway hazard and worsening an already dire road safety crisis.
Of course, crashes involving guardrails are not the only variety. Indeed, I strongly suspect they’re not the most common variety. We’ve known for years that drivers and passengers in bigger vehicles are much more likely than smaller ones to survive vehicle-on-vehicle crashes. And that, smaller vehicles—not to mention cyclists and pedestrians—are at a severe disadvantage against larger ones.
Ensuring that tomorrow’s cars do not slam through metal barriers and fly off the highway would require a wholesale upgrade of the nation’s guardrail installations, which Stolle estimated to cover at least 50,000 miles. Assuming a materials cost of $30 per foot, replacing all MGS guardrails could easily hit $8 billion, not including installation expenses that would drive the price tag much higher. (Retrofits could be less expensive, but Stolle said it’s too soon to know if they would be feasible.) To put that figure in perspective, $8 billion exceeds North Carolina’s entire annual transportation expenditures, and is almost six times Maryland’s transportation maintenance budget.
In a statement, a Federal Highway Administration spokesperson showed little interest in assuming responsibility for a future guardrail overhaul, saying that “states and local governments are responsible for properly selecting, installing, maintaining, and replacing roadside safety hardware, including guardrails,” and requesting that further questions be directed to them.
Unless there’s a spate of “behemoth” vehicles crashing through guardrails, I suspect this upgrade won’t happen. And that, if it does, it’ll be a gradual one, with sturdier versions replacing existing ones a the most dangerous locations and as old ones were due for replacement.
Who will ultimately foot the bill for reinforced guardrails? You, in all likelihood. There is ample precedent, since car bloat is already known to worsen a bevy of societal problems that range from pedestrian deaths to climate change to roadway erosion. Because the federal government has not imposed taxes to address those costs, all Americans bear the financial burdens of oversize vehicles—no matter how they travel.
Again, there’s no denying that there are negative externalities associated with “oversize” vehicles. But that’s more true of commercial vehicles than ordinary passenger cars. Our one-day delivery culture means that giant trucks are on the roads—including neighborhood streets—constantly.
Those who own larger vehicles do, of course, pay taxes to do so. They’re more expensive to purchase, in most cases, than comparable smaller models. Which means higher sales and property taxes. They consume more fuel, which means higher fuel taxes. Whether these are enough to offset the externalities, though, I haven’t the foggiest.
Car bloat is not a uniquely American problem; SUV sales are rising around the world, notably in Europe. Places like France, Norway, and the District of Columbia have enacted policies that force owners of the biggest cars to pay fees that at least partially compensate for the costs imposed on everyone else (and potentially nudge consumers toward smaller, less damaging models). But Congress and the Department of Transportation have shown no signs of following suit.
The United States is a vast country that, for a whole variety of reasons, requires people to be in their cars a whole lot more than is the case in France, Norway, or DC. It’s not at all shocking that this has led us to prioritize comfort over efficiency. Spikes in gas prices will temporarily cause panic buying of smaller cars but the demand for larger ones always rebounds.
It would be foolish, indeed, for the people’s representatives to punish them for this choice. But it would absolutely be reasonable to incentivize the purchase of more fuel-efficient vehicles. As, it turns out, we do. (Although, apparently, EVs come with the hidden danger of guardrail failure. The horrors!) And, yes, to the extent “behemoth” vehicles impose negative externalities, it’s reasonable to mitigate them, whether through design choices (bumper placement, more cameras to provide better visibility, etc.) or taxation.
In the meantime, a prisoner’s dilemma is catalyzing the shift toward vehicular enormity, prodding even those who prefer a modest-size car to get a bigger one simply to avoid being at a disadvantage on the road.
Again, this is not an unreasonable choice! In the linked piece, about a kerfuffle over a recommendation that parents get their teen drivers newer, bigger cars because they provide more crash protection, someone asks, “What about people outside the car?” That’s a reasonable question from a public policy standpoint but decidedly not the biggest consideration for said parents.
Unless federal policymakers finally acknowledge car bloat’s dangers, the result will be a dirtier, deadlier, and more expensive transportation network. And a lot of busted guardrails, too.
It turns out that the sneering was the point and the concern over guardrails merely an excuse to deliver it.