🚛 路上这么多卡车，它们到底在干什么？

The answer first: you are looking at the economy's bloodstream, and you're driving down its aorta

Almost nothing sold in America avoids a truck — rail and ships get things "nearby"; the last few hundred miles are always rubber on asphalt. As for why today looks extreme: I-81 is the East's truck freeway. It parallels I-95 without I-95's tolls and city congestion (remember #6?), so freight from Texas and the Southeast to the Northeast funnels up this valley. On stretches of I-81 trucks are 25–40% of traffic, among the highest of any Interstate. You didn't run into trucks by chance; you drove into their main channel.

Chapter 1 · What do they carry? — truck vs rail vs air

Sources: ATA American Trucking Trends 2025 (2024 data); BTS/CRS 2023 ton-miles.

The gap between the two charts is the whole logic of the industry: short hauls and the last leg belong to trucks; long-distance bulk belongs to rail. Above 500 miles, more freight moves by rail or rail-plus-truck than by truck alone. Air is invisible by weight but large by value — chips, drugs, your next-day parcel.

A gallon of diesel moves a ton nearly 500 miles by rail, ~150 by truck — steel on steel rolls far easier than rubber on road. So why hasn't rail won? Rail doesn't stop at your door, and US freight railroads are private (UP, BNSF, CSX, NS) running only the trunk lines that pay. The modern answer is intermodal: a container rides a train 1,500 miles and a truck takes each end. Half of J.B. Hunt's business is exactly that.

Chapter 2 · Whose truck? — the secret of the logo

Chapter 3 · The business model: how the money flows

The central fact: trucking is an extremely fragmented market with a layer of middlemen who own no trucks at all. Brokers take loads from shippers and post them on load boards (DAT, Truckstop.com) where small fleets and owner-ops bid. Brokers keep 12–18%. Big shippers (Walmart) sign annual contract rates with big carriers; loose freight moves at spot rates, which swing violently with the economy — a 2021 spike, then a 2023–25 collapse that bankrupted thousands of small carriers, known in the trade as the freight recession.

Industry structure: a very long tail

0.7% of companies own hundreds of thousands of trucks; 91.5% average one or two. That is how "driver shortage" and "drivers can't find loads" are both true at once — the giants are always hiring, the small owners are always waiting.

Chapter 4 · Who's driving? — the driver's view

What a day looks like

What it pays

Company drivers are paid per mile — not per hour. Three hours waiting at a warehouse dock pays nothing (the industry's biggest grievance, called detention). Owner-op gross looks scary until you subtract the truck note ($2–3k/mo), diesel ($60–80k/yr), insurance ($15–25k), tires and repairs — average net lands just over $70k, not far from a company driver. What's extra is freedom, and risk.

Is the shortage real? — yes, and no

ATA (the industry association) says 60–80,000 drivers short, every year. Economists (Penn's Steve Viscelli among them) push back: plenty of people earn CDLs; the problem is 87–90% annual turnover at the big truckload carriers — the whole workforce replaced yearly. Three weeks away from home, paid by the mile, unpaid waiting, and parking at 11 to 1 (4 million drivers competing for 311,000 legal spaces; seven in ten admit to parking illegally). Verdict: no shortage of licences — a shortage of people willing to stay. Local delivery and private fleets (Walmart) never complain of a shortage, because their drivers sleep at home.

Chapter 5 · Who builds them? — the four families of the cab

The ones you can recognize: Freightliner Cascadia (the rounded cab you see most, Daimler of Germany); Peterbilt / Kenworth (square, chrome, long hood — PACCAR, the owner-operator's favourite and the face of the "American truck"); Volvo VNL / Mack (Swedish); International (now VW's Traton). A new long-haul tractor is $150–200k, plus $50k for the trailer — an owner-operator on the road is driving a house's worth of money.

Class 8 = gross weight over 33,000 lb. The 18-wheeler beside you grosses 80,000 lb (36 t) loaded — eighteen Model Ys.

Chapter 6 · The derivative industries: how many businesses one truck feeds

Chapter 7 · What it's like to drive an 18-wheeler — licence, blind spots, driver aids

Chapter 8 · Autonomy: where it really stands in 2026

Why trucks commercialized before robotaxis: the freeway is the easiest scene (no pedestrians, no intersections), the economics are the clearest (the driver is ~40% of cost, and a driverless truck runs 22 h/day with no HOS), and regulation is loosest (Texas). Why it hasn't spread: $100k+ of sensors and compute per truck, fair-weather and fixed lanes only, humans still needed at the exits and in cities (the "hub-to-hub" model). For drivers: the dullest Texas–Arizona lanes go first within a decade; local, complex and winter routes get more short-handed.

Chapter 9 · What the startups are changing

Epilogue · Tonight you'll sleep next to them again

Back to where this started: you spent a night in a Carlisle Walmart lot listening to trucks start and stop — drivers squeezed out by an 11:1 parking gap, executing a 14-hour federal rule in a 36-ton machine. In every cab beside you on I-81 tomorrow sits someone paid by the mile, three weeks from home, watched by an AI camera, carrying something you may sign for on your porch next week.