Bridge Law Calculator: axle weight layout software for trailer companies
Lay out trucks and trailers, see every axle load, and check the federal bridge formula and state bridge laws, then print a clean weight-layout sheet. The free calculator covers straight trucks up to 3 axles and tractor-semitrailers up to 5 axles, checked against the federal bridge formula. State bridge laws, truck + pup, doubles, triples and the other tools below are in the full version. It runs in your browser. The free version doesn't save your work; the full version saves and shares calcs.
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What the Bridge Law Calculator does
Truck & trailer library
Start from library tractors and trucks instead of typing every dimension. Library values show their source and confidence so you know what is published and what is assumed. (full version)
Scale tickets
Save scale tickets, compare them with the calculated loads, and use real empty weights in the layout. (full version)
Drag-and-drop layout
Drag axles, kingpins and loads on the drawing and watch the axle loads update. Photo or drawing backgrounds to trace real dimensions are in the full version.
Bridge formula + 50-state checks
Federal bridge formula on every axle group (free), plus rule sets for all 50 states and DC, Interstate and non-Interstate (full version). Questions about a specific state? Ask us.
Many configurations
Free: straight trucks up to 3 axles and tractor-semitrailers up to 5 axles. Full version: truck + pup, doubles with converter dollies, triples, B-trains, straight trucks with pushers and tags, and more axles. Lift axles and set-load air axles are modeled.
Optimizer & print sheets
Find the axle position or load position that stays legal, compare up to three scenarios, and print a one-page weight-layout sheet for the customer or the shop.
Quick check vs. the full Bridge Law Calculator
| Feature | Quick check | Free calculator | Full version |
|---|---|---|---|
| 5-axle tractor-trailer and simple straight truck | Yes | Yes | Yes |
| Straight trucks (steer, pushers, drives, tags) | Simple | Up to 3 axles | Up to 11 axles |
| Tractor-semitrailers | 5 axles | Up to 5 axles | More axles |
| Truck + pup, doubles, triples, B-trains | No | No | Yes |
| Federal bridge formula | Yes | Yes | Yes |
| 50 states + DC rule sets | No | No | Yes |
| Tap-to-edit drawing, drag loads, basic printable report | No | Yes | Yes |
| Multiple loads, branded PDF report, saved setups | No | No | Yes |
| Company accounts, private and shared design libraries | No | No | Coming soon |
Open the calculator · Full version
Shared design library (coming soon)
Each company keeps its own private designs. Manufacturers can publish designs to a global library that every Bridge Law Calculator user can lay out, with the manufacturer's name and a link back on every design. How the design library works →
Pricing
The free calculator (straight trucks up to 3 axles and 5-axle tractor-trailers, federal bridge formula) costs nothing. Pricing for the full version will be posted before it opens. Company accounts (team seats, private design libraries and the shared design library) are coming soon as an annual subscription. Pricing, seats and trial terms will be posted before launch. Want details sooner? Ask a question.
Full-version accounts are open
All rigs, state checks, multiple loads, PDF reports and saved calcs. Have an account? Sign in to the full version. Need one? Request full access. Questions? Ask a question.