Methodology Notes

Every number on this site came from somewhere, and you should be able to trace it. This page lists the source material behind each category of figure, how figures get cross-checked, why we print ranges when sources disagree, how often pages refresh, and where the limits sit. If a page ever cites a figure you can't trace back through these notes, tell us through the contact page and it gets fixed or logged on the Corrections Log.

Primary Sources by Category

Cost-per-Mile and Operating Cost Benchmarks

Operating cost figures — fuel cost per mile, maintenance cost per mile, insurance cost per truck per year, driver wages as a share of marginal cost — come from the 2024 ATRI/ATA Operational Costs of Trucking survey. That's the American Transportation Research Institute's annual carrier survey, produced in cooperation with the American Trucking Associations, and it's the standard industry benchmark for what it actually costs to run a truck. The survey collects real cost data from fleets of all sizes, which is why we use it instead of trade-press estimates: a number built from hundreds of carriers' ledgers beats one built from phone calls.

When you see a figure like "marginal cost per mile for a semi tractor averaging in the low two-dollar range" on our fleet economics pages, the anchor is the ATRI survey. When you see a cost breakdown by component — fuel, labor, maintenance, insurance, permits — the component shares come from the same source, sometimes adjusted with the fuel-price caveat described in the ranges section below.

Violation Rates and Out-of-Service Percentages

Inspection and enforcement statistics — vehicle out-of-service rates, driver OOS rates, the most common violation codes, brake and tire defect frequencies — come from two FMCSA sources: the Safety Measurement System (SMS) public data and the DataQs system, which is the channel carriers use to challenge erroneous inspection records. SMS gives us the aggregate picture: how many inspections happen, what they find, how carriers score across the BASIC categories. DataQs matters to us for a different reason — the volume and type of challenges carriers file tells us which violations are most frequently contested and which get overturned, which informs the "is this worth fighting" guidance in our inspection guides.

Both are public datasets; what we add is the compilation and the translation into decisions — which violation categories generate the majority of OOS orders, and therefore where a pre-trip inspection checklist earns its keep.

CVSA International Roadcheck Results

The annual Roadcheck blitz numbers — inspections conducted, vehicles placed out of service, top violation categories during the blitz — come from the Commercial Vehicle Safety Alliance's published International Roadcheck results. The 2024 blitz ran June 4–6, 2024, and CVSA publishes the results each year in the months that follow. Roadcheck data matters because it shows what inspectors focus on when they're explicitly looking: the emphasis categories CVSA announces each year (hours-of-service and tractor protection systems have been recent focuses) are the categories that spike in the results. If our DOT inspection prep material tells you to check specific items before a blitz week, this dataset is why.

Registration Fees, Permits, and State-Level Charges

State-by-state fees — IRP apportioned registration costs, overweight and oversize permit fees, highway use taxes, UCR brackets — come from the state DOT and DMV fee schedules themselves. This is the least glamorous source category and the most labor-intensive: fifty jurisdictions, each with its own fee table, its own update schedule, and its own talent for burying the current schedule three menus deep on a redesigned website. We pull the published schedule, note its effective date, and record the pull date. When a page says a New York Highway Use Tax figure or a specific state's IRP base plate fee, it reflects the schedule as of the pull date noted in our working files.

UCR fee brackets come from the UCR Plan's published annual bracket table. The brackets change year to year — sometimes the fees drop, as they did for one recent registration year — and a stale bracket is one of the most common errors we see copied around the internet. It's also, candidly, the category where we've logged corrections ourselves. See the Corrections Log for the receipts.

IFTA Fuel Tax Rates

Quarterly fuel tax rates by jurisdiction come from the IFTA Inc. quarterly fuel tax rate matrices — the official matrices published for each quarter. IFTA rates change every quarter in some jurisdictions and hold steady for years in others, which is why a rate table without a quarter label is a rate table you shouldn't trust. Our IFTA pages and guides label the quarter explicitly, and when a new matrix drops we reconcile the affected figures. The reconciliation isn't always instant — a mid-quarter matrix update can lag our page update by days — and when a lag produces a wrong figure on a live page, it gets a dated entry on the Corrections Log, not a quiet edit.

Federal Heavy Vehicle Use Tax

HVUT figures — the tax rates by weight class, the $550 annual maximum, the July filing period, the suspended-vehicle mileage threshold — come from the IRS Form 2290 instructions and the underlying statute, 26 U.S.C. § 4481. This is the most stable category we track: the HVUT rate structure has been essentially unchanged for years, and instruction updates are usually procedural rather than rate changes. Stable doesn't mean ignored — we re-read the current instructions each filing season.

How Figures Get Cross-Checked

No figure goes on a page from a single read of a single source. The standard check has three steps:

1. Primary pull. The number is taken from the primary source — the survey, the matrix, the fee schedule, the instructions — with the effective date recorded.
2. Secondary confirmation. Where a second legitimate source exists (a state revenue department page confirming an IFTA rate, FMCSA's own summary confirming an SMS trend, a prior-year figure for sanity comparison), the number is checked against it. If the secondary source disagrees with the primary, the primary source wins — but the disagreement gets noted, because a disagreement between two official sources usually means a change is in flight.
3. Plausibility check. The number is compared against its own history and its neighbors. If every surrounding state's diesel rate sits between $0.30 and $0.40 and one state shows $0.89, someone reads that entry twice before it publishes. Outliers exist — some states genuinely tax at multiples of their neighbors — but outliers get verified, not assumed.

And the check runs in both directions on update. When a source refreshes, we don't just look for what changed; we check that what didn't change actually should have stayed the same. A fee schedule republished with identical numbers still gets spot-checked, because agencies occasionally correct a figure without announcing it.

Why We Print Ranges

You'll notice our cost figures are often ranges — "insurance runs $9,000 to $14,000 per power unit per year for many small carriers," that kind of thing — rather than a single precise number. That's not hedging. It's honesty about the underlying data.

Sources disagree for real reasons. The ATRI survey averages across carriers of wildly different sizes, regions, and freight types; a fuel cost per mile that assumes one diesel price is obsolete the month diesel moves fifty cents. Two legitimate fee-tracking sources can be one update cycle apart. When the honest answer is a band, we print the band and say why. A single number printed with false precision — "$11,847 per year" — looks more authoritative and is less true. An owner-operator building a budget from our pages deserves the range, because his actual quote is going to land somewhere in it and he needs to know the width of it before he signs a truck note.

What "2024 Averages" Means

When a page says a figure is a "2024 average," it means the source data covers calendar or fiscal 2024 operations, as published in the 2024 edition of the source — and it means average in the statistical sense: the midpoint of a wide spread. The average maintenance cost per mile hides carriers running brand-new equipment at half that figure and carriers nursing fifteen-year-old trucks at double it. So use our averages as benchmarks to compare against your own books, never as a substitute for them. Your cost per mile is the one in your accounting software; ours tells you whether yours is out of line.

Update Cadence

Update timing follows the source calendar, not an arbitrary schedule:

Pages carry their sources' effective context in the text. If you're reading an IFTA rate on this site in a later quarter than the matrix it came from, treat it as history, not gospel, and verify against the current matrix before filing.

Limitations — Read This Part

Regulations change, fee schedules change, and enforcement priorities shift. Nothing on this site replaces verifying current requirements with your base jurisdiction, your state DOT, FMCSA directly, or a qualified professional before you file, pay, or sign. We compile carefully and correct publicly — but the authoritative version of any rule is the current official one, not anyone's summary of it, ours included.

Three specific limits to keep in mind. First, lag: a source can change faster than we can update, and there will always be a gap measured in days or weeks. Second, scope: we track the major federal programs and the state-level items with the broadest impact; local and municipal requirements — city permits, county fees, port-specific rules — are largely outside our coverage. Third, interpretation: we describe what published rules say and how carriers commonly handle them. How a rule applies to your specific operation, your contracts, and your history is a question for your base jurisdiction or your attorney.

When we get something wrong despite all of this — and every research operation does eventually — the fix and the date go on the Corrections Log. Nothing gets silently edited. That's the accountability half of the methodology, and it's the page that keeps this one honest.