Low-Speed Off-Tracking (Swept Path)

OT = R - sqrt(R^2 - sum(L^2)), R the turn radius and L each unit's wheelbase (tractor wheelbase + trailer kingpin to axle, summed in quadrature). A single unit with a 20 ft wheelbase on a 50 ft radius off-tracks 4.2 ft. The low-speed check for whether a rig holds its lane on a turn or intersection. High-speed off-tracking (rear swings out) and swept-path width are separate; the design vehicle and agency govern.

OT = R - sqrt(R^2 - sum(L_i^2)); effective wheelbase = sqrt(sum(L_i^2)). R the turn radius, L_i each unit's wheelbase (tractor wheelbase + trailer kingpin-to-rear-axle).

AASHTO Green Book (Policy on Geometric Design of Highways and Streets) low-speed off-tracking; standard swept-path geometry.

transportation.org for TOC; the geometric off-tracking relation is public. AASHTO design-vehicle tables are licensed.

Math aid for personal verification. The ELD on the truck and the carrier tariff are the legal record. State limits may be lower than federal.

Field names used by the API: turn_radius_ft, wheelbase1_ft, off_tracking_ft, effective_wheelbase_ft

• Low-speed geometric steady-state OT = R - sqrt(R^2 - sum(L_i^2)); rear tracks insideAASHTO Green Book
• Effective wheelbase units summed in quadrature; tractor WB + trailer kingpin-to-axleswept-path geometry
• Scope not high-speed off-tracking (rear swings out) or swept-path width (add vehicle width)analysis scope