ERTMS

What is it

The European Rail Traffic Management System (ERTMS) is a standardised digital signalling and train control system designed to replace the patchwork of national mainline signalling and train protection systems across Europe. It combines in-cab signalling with automatic train protection, enforcing permitted speeds and movement authorities to maintain safe separation between trains.​

ERTMS comprises the dedicated railway radio system, GSM-R, and the European Train Control System (ETCS). The latter continuously supervises a train’s speed, using information sent from trackside equipment (balises and/or radio) to an onboard computer that enforces safe limits and braking curves.

Why it matters

ERTMS enables interoperability, allowing trains equipped to a common standard to run across borders without multiple signalling systems onboard. It also improves performance by supporting higher speeds, closer headways and more reliable operations, while reducing lifecycle costs through rationalised, harmonised equipment and procedures.​

Who uses it 

ERTMS is deployed by infrastructure managers and railway undertakings on passenger and freight networks, including high-speed, conventional and dedicated freight corridors. It is mandatory for certain EU core network routes and has been adopted by many railways and suppliers worldwide as a reference standard for modern train control.​

Where it is used

In the UK, the Cambrian Line in Wales became the UK’s first ERTMS/ETCS Level 2 route in the early 2010s. The technology also covers sections of the Thameslink and Crossrail/Heathrow corridors. Within Europe, ERTMS is rolled out on core TEN-T corridors and key high-speed and conventional main lines, with progressive extension to wider national networks. Beyond Europe, variants of ERTMS/ETCS and GSM-R are in service or planned in countries such as China, India, Saudi Arabia, South Korea and others seeking interoperable, high-capacity rail systems.​

When: key dates

ERTMS is active whenever trains operate over equipped lines, continuously supervising movements from start-up to shut-down of a trip. Development began in the early 1990s, first specifications appeared around 2000, and the earliest commercial ERTMS/ETCS lines entered service in the early 2000s, with large-scale deployment continuing since.​

How it works

ERTMS centres on ETCS onboard equipment that calculates a safe speed–distance profile from movement authorities and track data sent by balises or radio. GSM-R (and its successors) carries continuous data and voice between train and control centre, enabling in-cab signalling, automatic enforcement of limits and, at higher levels, removal of lineside signals to increase capacity and reduce maintenance.​

ETCS comprises several ‘levels’ at which the train control system may be applied. With ETCS Level 2, lineside signals become obsolete as movement authority decisions are transmitted directly to the driver’s cab. Network Rail is rolling out ETCS Level 2 as its default ‘digital signalling’ solution via incremental, corridor-based programmes, centred on the East Coast Digital Programme (ECDP), then extending through renewals-led deployment across other main lines during its Control Period 7 (CP7, 2024-2029) and beyond.