The dynamic outline of a train as it moves down the track, factoring in suspension sway, curve overhang, wheel wear, and track cant. Engineers use this measurement to ensure trains will clear tunnels, station platforms, and trackside signals without striking them. It is always larger than the static physical dimensions of the stationary railcar.
Heard on the job
We can't route those new double-stacks through the old tunnel because they exceed the kinematic envelope on the curves.
Insider tip
Track maintenance crews must strictly maintain superelevation on curves, as excessive tilt can push a tall car outside its kinematic envelope and into adjacent structures.