A track configuration where a train approaches the frog before the switch points, meaning two tracks merge into one. Passing through a trailing switch is inherently safer than going through facing points because the wheel flanges naturally push through the correct path, reducing the risk of picking a switch and derailing.
Heard on the job
We can run through that trailing turnout at track speed, no need to line it back.
Insider tip
Running through a trailing switch that is lined against you will force the points open, which damages the mechanism unless it is specifically designed as a trailable switch.