Highway Capacity Manual · 7th Edition
HCM Calculator
A browser-based implementation of HCM analysis procedures. Compute level of service, follower density, and operating speeds segment by segment — backed by a WebAssembly engine for exact, reproducible results.
Highway Capacity Manual, 7th Edition
WebAssembly engine
Calculations run locally in a compiled Rust core — fast, offline, and identical on every run.
HCM-faithful methodology
Follows the manual step by step, including vertical and horizontal alignment effects on each segment.
Reproducible analyses
Import and export inputs as JSON to version, share, and re-run any study exactly as configured.
Available chapters
— Additional chapters Further HCM procedures are being implemented Planned
Built by Rei Tamaru, an ITS Engineer at HNTB. This is an independent, personally built tool and is not affiliated with any organization or corporation.
Questions or issues? Feel free to open an issue on GitHub.