TPWS

Train Protection & Warning System

Loop-based automatic train stop and speed traps to prevent SPADs and overspeeding into hazards.

Driving Difficulty Level 3 / 5

Intermediate

Based on vigilance required, reaction window, and braking penalty severity.

menu_book System Overview

TPWS supplements AWS across the UK railway network. It uses magnetic wire transmitter loops laid on track sleepers to automatically apply the brakes if a train approaches a red signal too fast or passes it completely.

settings How It Operates

check_circle TSS (Train Stop System): Placed directly at red signals. Immediately drops train brake pipe to zero if a train passes the signal at danger (SPAD).
check_circle OSS (Overspeed Sensor System): Consists of an Arming Loop and a Trigger Loop spaced according to route speed. If the train covers the distance faster than the timer threshold, emergency brakes trigger.
check_circle Operates invisibly until an overspeed or SPAD occurs; no driver button presses are required during normal running.
check_circle Once tripped, the brakes cannot be released until the train comes to a complete halt and the TPWS brake demand light clears.

visibility In-Cab Visual & Audio Indications

notifications Brake Demand Lamp

Flashing red or yellow indicator illuminates on the cab panel when emergency braking is enforced.

notifications Temporary Isolation Lamp

Illuminates when override mode is active.

lightbulb Driver Tips to Avoid Penalty Brakes

verified Always respect braking curves approaching red signals; an OSS speed trap is usually placed 200-400m before the signal.
verified If TPWS trips, set the throttle to idle and wait 60 seconds after stopping for the brake demand to reset.