Why running trains across European borders is so hard
EXPLAINER: European trains are harder to run across borders than within them — and the reasons are technical, institutional and political, not geographic.
Each country built its railway system independently, producing incompatible signalling, electrification and safety rules that a cross-border train must navigate simultaneously. A single journey from London to Rome today crosses multiple voltage systems, several signalling regimes and a patchwork of national operating rules — each requiring certified equipment or qualified crew.
Why the networks don’t connect cleanly
The most visible legacy of national railway building is track gauge — the width between the rails. Most of Europe uses standard gauge at 1,435 mm. Spain and Portugal built their networks to a wider 1,668 mm, which is why trains historically stopped at border stations like Port Bou and Hendaye rather than continuing across. Passengers changed trains; cargo was transferred or wheelsets were swapped.
Spain has since built its high-speed network to standard gauge, but the legacy broad-gauge mainline network remains. The border problem did not disappear — it shifted.
The electrification patchwork
Europe’s railways were electrified country by country, each adopting the technology available at the time. The result is four principal systems operating across the continent: 25 kV AC at 50 Hz, used across France, Denmark, Finland and Spain’s high-speed lines; 15 kV AC at 16.7 Hz, used in Germany, Austria, Switzerland, Sweden and Norway; 3 kV DC across Belgium, Italy and Poland; and 1.5 kV DC in the Netherlands and parts of France.
A train crossing from Germany into Belgium crosses two of these systems within a single journey. Multi-system locomotives and trainsets can handle the transition, but they are more complex and more expensive to build and certify than single-system vehicles.
Signalling: the hardest barrier
Track gauge is visible. Electrification can be managed with the right equipment. Signalling is harder.
Each country developed its own train control and safety system, and by the turn of the century more than 20 different national systems were in use across Europe. Eurostar, which operates across five countries, contends with multiple different signalling technologies — requiring onboard equipment for each and drivers certified in every territory crossed.
The EU’s response is the European Train Control System (ETCS), the signalling component of the broader European Rail Traffic Management System (ERTMS). ETCS provides a single, standardised cab-based signalling standard designed to replace national systems over time. The European Union Agency for Railways (ERA) coordinates the rollout and has reduced the volume of national technical rules from around 14,000 to approximately 800 since 2016.
Progress is real. It is also slow.
The institutional problem
Behind the technical barriers is a structural one. Europe’s railways were built to serve national markets, and the organisations that run them have historically had little incentive to fix what happens on the other side of the border. The head of ERA has described the result as collective irresponsibility: each actor assumes the cross-border problem belongs to someone else.
EU legislation opened international passenger rail to competition in 2010, and the Technical Specifications for Interoperability (TSI) provide the regulatory framework for standardisation across rolling stock, infrastructure and signalling. ERA now acts as the central authorisation body for vehicles operating across multiple member states, removing the need for separate national approvals.
But the framework and the reality remain some distance apart. Timetable coordination across borders is still inconsistent. Some cross-border lines operate with mismatched frequencies. A handful of internal EU border crossings have seen services reduced or discontinued in recent decades.
What changes — and what doesn’t
The direction is clear. ERTMS deployment is accelerating across the core TEN-T network, and the EU’s revised TEN-T regulation requires minimum speeds of 160 km/h on core network rail lines by 2040. New rolling stock orders increasingly specify multi-system capability as standard.
What does not change quickly is the installed base. Thousands of kilometres of legacy infrastructure, hundreds of older vehicles and decades of nationally siloed operational practice do not transform on a regulatory timeline. The European rail network is becoming more interoperable. It is not yet one system.