INPUTS
Fills the dimensions below; tweak freely.
Car dimensions (model, over the body)
End to end (not couplers)
Bolster to bolster
Body width
Curve
Centerline radius. Use a preset or type your own.
Adjacent-track clearance (two cars on parallel curves)
Center-to-center between the two tracks. HO straight-track norm is ~2".
RESULTS
End outswing
—
corner past the railhead (outward)
Mid inswing
—
middle pulled toward curve center
Adjacent-track clearance
—
—
Recommended track centers on this curve
—
Car body
Track centerline / rails
Adjacent car
Long cars that overhang badly also foul sidings differently — size your trains in the Siding Capacity tool.
Mid inswing = R − √(R² − (truck centers/2)²). End outswing is the car corner’s radial distance beyond the centerline. Adjacent-track need = car width + (end outswing + mid inswing). Geometry is a rigid-body approximation; real couplers and truck swing vary. Confirm critical clearances physically.