An Australian road train carrying fuel - Darrian Traynor/Getty ImagesThere is something inherently satisfying about watching a massive vehicle moving past you, such as seeing the American Class 8 semi-truck rolling down Interstate 80 with its 53-foot-long trailer. If you're lucky enough, you'd encounter a turnpike double, or on the rare occasion, a triple trailer allowed in a few states, such as Ohio. That's a lot of truck. However, catch a flight and travel to the southeast before taking a pickup and traveling a few hundred miles, and you'd reach the desolate expanse of the Australian Outback. That's when you realize that America's biggest rigs look like toys compared to the apex predator of Australia's logistics network — the Australian road train.These aren't just trucks. They are literal freight trains without steel tracks, barreling across thousands of miles of the brutal Australian Outback. To fully comprehend the size of a road train, you have to look at the ridiculous numbers. In the United States, the length of a semi-truck is capped at around 70 to 80 feet, and when you consider a triple-trailer (a Long Combination Vehicle), the maximum combined length is 115 feet. In Australia, a standard Type 1 road train featuring a prime mover and two full-size trailers stretches up to 120 feet, while a Type 2 road train gets up to three trailers, reaching a staggering 175 feet. Head to the remote Outback of Western Australia, and you may find quad trains, and if you are lucky enough, witness extreme hauling in the form of five or more trailers. However, that's still not longer than the longest vehicle ever — a trackless overland train meant to run on nuclear power.AdvertisementAdvertisementRead more: 10 Of The Strangest Boeing Aircraft Ever MadeWhy can't we have road trains?An Australian cattle road train carrying four trailers - Shirley Jayne Photography/ShutterstockRoad trains can weigh up to five times the weight of a semi-truck, so why don't American trucking companies adopt these hyper-efficient, hyper-long trucking solutions to cut shipping costs? The short answer is that, while we did have a snow train developed by the US Army, the United States is structurally, geographically, and regulatorily opposed to the road train concept for several reasons.The American interstate highway system was engineered in the mid-20th century to accommodate standard-sized commercial semi-trucks, with tight radius cloverleaf interchanges, and dense metropolitan merging lanes. Driving a 175-foot-long vehicle requires an enormous amount of physical space just to make a simple turn. In Australia's Outback, intersections are few and far between, and are designed with a massive turning radius. If you tried to navigate a three-trailer road train through a standard American highway exit ramp or a suburban delivery hub, the rear trailers would simply off-track, destroying guardrails, crushing concrete barriers, and wiping out utility poles. In fact, the U.S. Federal Highway Administration strictly enforces axle weight limits and overall length laws to preserve bridges and roads. The capped gross vehicle weight of six-axle semi trucks travelling on federal highways is 80,000 pounds, which is far less than a 380,000-pound road train.AdvertisementAdvertisementThe United States is a hyper-connected web of heavily congested freeways and constant stop-and-go traffic. The braking distance of a road train travelling at 60 mph is enormous, so mixing road trains with millions of unpredictable commuter cars on U.S. highways could have catastrophic consequences. Meanwhile, many parts of Australia are barely inhabited, such as the Northern Territory outside the Greater Darwin area, which has a population density of roughly 0.5 people per square mile.Can America ever have road trains?A warning sign about road trains in the Australian Outback - Alan Morris/Getty ImagesIf a coalition of politicians decided that they should bring in the Australian-style road trains to America, the required infrastructure transformation would easily be a multi-billion-dollar engineering undertaking. First, federal and state legislations would need to be completely rewritten. The decades-old 80,000-pound federal total weight limit would have to be abolished for designated routes. The State Department of Transportation would also have to replace the traditional weight limits per axle to 20,000 pounds and per tandem axle to 34,000 pounds with Australia's framework that allows specialized heavy-duty permits for road trains.From an infrastructure perspective, thousands of miles of highways would require extensive physical reconstruction to prevent damage. Many highway off-ramps would have to be rebuilt with incredibly wide, sweeping geometric curves to prevent tracking trailers from leaving the asphalt. Furthermore, hundreds of highway bridges would require complete structural reinforcement to handle the immense localized weight of multiple 130-ton vehicles passing through. Truck stops, weight stations, and rest areas would also need massive staging zones just to give these long vehicles a place to park or unhook extra trailers before entering urban areas.Where could a road train hypothetically work? There are a select few corridors in America that mimic the vast openness of the Australian Outback. The flat, desolate stretches of Interstate 80 across Nevada, the long expanses of Interstate 10 and Interstate 20 cutting across the barren desert of West Texas, and the wide open plains of Interstate 94 through North Dakota and Montana could hypothetically accommodate road trains. These specific routes feature minimal congestion, long straightaways, and vast distances between major metropolitan hubs. It's a fascinating logistical dream, but given the staggering cost of infrastructure modification and safety risks, the American road train feels like a pipe dream for now.AdvertisementAdvertisementWant more like this? Join the Jalopnik newsletter to get the latest auto news sent straight to your inbox, and add us as a preferred search source on Google.Read the original article on Jalopnik.