Highway Capacity Manual · 7th Edition

HCM Calculator

A browser-based implementation of HCM analysis procedures across fourteen chapters: freeways, urban streets, signalized and stop-controlled intersections, roundabouts, interchanges, and multiuse paths. Every chapter reproduces its published HCM worked examples, computed by a WebAssembly engine that also works offline. Interactive 2D and 3D diagrams, traffic animation, and printable run reports included.

Browse chapters HCM 7th Edition reference

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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

Fourteen chapters, each validated against its published HCM worked examples

10 Freeway Facilities Core Methodology Whole-facility analysis over 15-min periods, composing basic, merge, diverge, and weaving segments Available 11 Freeway Reliability Analysis Whole-year travel time reliability with demand variation and incident scenarios Available 12 Basic Freeway and Multilane Highway Segments Free-flow speed, capacity, density, and level of service for basic freeway segments Available 12ML Basic Managed Lane Segments Capacity, speed, density, and level of service for a managed lane, including the friction effect of the adjacent general purpose lanes Available 13 Freeway Weaving Segments Weaving and nonweaving speeds, capacity, and LOS, under the 7th Edition or Edition 7.1 Available 14 Freeway Merge and Diverge Segments Ramp influence area density, speeds, and LOS, under the 7th Edition or Edition 7.1 Available 15 Two-Lane Highways Level of service, follower density, average speed, and passing analysis Available 16 Urban Street Facilities Facility travel speed, spatial stop rate, and LOS aggregated over a chain of urban street segments Available 17 Urban Street Reliability and ATDM Travel time distribution, travel time index percentiles, and reliability rating over a year of generated weather, demand, and incident scenarios Available 18 Urban Street Segments Free-flow speed, running time, travel speed, stop rate, and LOS for one direction of an arterial segment Available 19 Signalized Intersections Control delay and LOS by approach for a pretimed four-leg signal Available 20 Two-Way STOP-Controlled Intersections Gap-acceptance capacities, delay, and LOS by movement rank, with the December 2022 corrections Available 21 All-Way STOP-Controlled Intersections Departure headways, control delay, queues, and LOS per lane and approach Available 22 Roundabouts Entry capacities, delay, queues, and LOS, including right-turn bypass lanes Available 23 Interchange Ramp Terminals O-D experienced travel time and LOS for diamond and DDI interchanges and RCUT, MUT, and DLT alternative intersections Available 24 Off-Street Pedestrian and Bicycle Facilities Pedestrian space and events, and the bicycle BLOS score for shared-use paths Available

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.