Rail traffic in Europe: why is it so complicated?

Written by Georges Benisty

Published yesterday

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Since the 2000s, rail traffic in Europe has grown significantly... Yet despite these advances, the European rail network still faces major technical challenges that prevent full harmonisation. Here’s everything you need to know.

Technical Fragmentation of the European Rail Network

Overhead Line Voltage Differences

For electric trains, power is supplied via the overhead line system — the wires suspended above the tracks. However, this electrical supply varies greatly from one country to another, complicating interoperability.

For example:

• In France, electric trains use two types of voltage: 1500 volts (DC) and 25,000 volts (AC).
• In Belgium and Italy, the standard is 3000 volts (DC). But even this common voltage poses problems: a train that can operate on 3000 volts in Belgium may not be compatible in Italy due to differences in pantograph standards — the device on the train that collects electricity — as defined by each country’s network reference documents.

These discrepancies stem from post-WWII technological choices, when current conversion technologies were less developed and the priority was domestic travel. Today, cross-border rail travel is increasingly favoured in the geopolitical context.

While the 2023/1693 EU regulation now mandates that all new lines be electrified at 25,000 volts, achieving a unified voltage across Europe will take decades.

Rail Signalling Systems

Signalling is another major obstacle. Each European country has developed its own onboard system to display critical information like speed limits and stop signals. As a result, trains crossing multiple borders must be equipped with various systems, and drivers must be trained in each of them.

They must understand signals clearly — even in abnormal situations like a signal failure.

Take a look at the OpenRailwayMap — it reveals just how many different signalling systems exist across Europe:

Source : openrailwaymap.org

For instance, the current Eurostar trains (formerly Thalys) were among the most expensive to purchase from Alstom. Why? They had to adapt to the voltage differences across multiple countries and integrate up to seven signalling systems (two for France, two for Belgium, one for the Netherlands, and two for Germany), depending on the trainset.

To address this, Europe has introduced a standard called the European Train Control System (ETCS) to unify signalling across borders.

But implementation will take decades. Each country must adopt ETCS, install it across its network, and retrofit trains to make them compatible. These upgrades cost billions of euros and will only pay off over time.

Some countries are leading the way: Switzerland has implemented ETCS across 100% of its standard-gauge network, and Belgium has already equipped over 50% of its network.

Track Gauge Differences

Track gauge — the distance between the rails — is often overlooked but varies across Europe.

Switzerland is a standout example, with many narrow-gauge (under 1 metre) lines. Spain is another case: due to its railway development outside British influence, its traditional network uses a wider gauge of 1.668 metres.

New cross-border lines, like the Paris–Barcelona TGV or AVE routes from Marseille to Madrid and Lyon to Barcelona, use the EU-standard 1.435-metre gauge.

Directive 2016/797 now requires all new EU lines to adopt this standard gauge to improve interoperability — especially with France, which already uses it extensively.

Authorisations: A Complex Process

For Rolling Stock

For a locomotive or carriage to operate across several European countries, it must receive approval from each one.

For example, NightJet trains between Paris and Vienna (crossing France, Germany, and Austria) must be certified in all three.

Since the Fourth Railway Package came into effect in 2020, the European Union Agency for Railways (ERA) now issues these certifications.

Key steps include:

• Technical assessment to ensure compliance with safety and interoperability standards in each country. (In Italy, for example, trains must pass specific tunnel fire-resistance tests.)
• Compatibility checks with infrastructure (voltage, signalling, track gauge).
• Registration in the European Register of Authorised Vehicle Types (ERATV).

This process is long and demanding. It often reveals design issues that must be corrected before certification.

This is one reason train development cycles are long. For instance, the launch of European Sleeper’s Brussels–Prague route was repeatedly delayed due to difficulties finding certified rolling stock for all four countries involved.

For Train Drivers

More trains mean more staff to operate them — and not just ticket inspectors.

Drivers undergo rigorous testing: first on general railway knowledge, then on specific types of trains and routes. Why so thorough? Because they’re responsible for the safety of hundreds, sometimes thousands, of passengers — often at speeds over 300 km/h.

They must never doubt their speed, route, or braking timing. Here’s why it matters to you: if — and we hope this never happens — a train hits a person or vehicle, the driver must immediately brake, alert the operations centre, and secure the train. All this while dealing with potential shock.

They’re then relieved and replaced by another qualified driver. But here’s the catch: the new driver must also know both the train and the route. With rising traffic and limited budgets, there’s not always a fully qualified reserve driver on standby. That’s why some trains terminate early — simply because no replacement is available.

Drivers covering these situations are called reserve agents. Their on-call time counts as working hours. If they exceed their shift limit during the replacement, someone else must take over.

And it gets more complicated: night-time driving requires an additional certification. This scarcity of night-certified drivers limits how many night trains can operate — and therefore, how many low-carbon journeys are possible.

Maintenance Works

Frustrated by track works? They're essential. Regular maintenance ensures safe travel. Europe’s ageing rail infrastructure means frequent and often long-lasting works — especially at strategic locations — which can disrupt service. If a section is closed or key stations are skipped, alternative routes must be found. Germany’s dense network makes rerouting easier. Other countries may face detours of hundreds of kilometres before reconnecting to the main route.

Infrastructure managers must ensure that rerouted trains won’t interfere with others — or limit disruption as much as possible. Since the liberalisation of rail in 2020, network managers have become increasingly independent from national operators. As a result, infrastructure planning doesn’t always align with operators’ priorities.

Sometimes, essential work is scheduled with minimal notice or frequent disruption. This frustrates operators. For instance, ÖBB (Austria’s federal railway), which helped revive night trains in Europe, postponed its Zürich–Barcelona service, which would have served southern France. Similarly, the planned Paris–Berlin night train was cancelled: works across Germany pushed rerouting options to their limit.

As a conclusion, Europe has made impressive progress in rail travel since the early 2000s. But full technical harmonisation remains a distant goal. Voltage inconsistencies, signalling complexity, and demanding authorisation procedures continue to pose major challenges — requiring massive investment and stronger cooperation between EU members.

The road (or rather, the rail) to an integrated European network is long — but essential to meet the rising demand for sustainable travel.

We've highlighted the key technical and human factors shaping train travel in Europe today — but trust us, there are many more!