EU Rail Electrification: A Unified Future & Energy Savings in Italy

Introduction

Railway and Transportation Engineer Ivan Beltramba discusses the challenges and potential solutions for achieving a unified overhead electrification system across Europe, a critical step toward the Single European Railway Area (SERA). Beltramba notes that despite the European Commission’s designation of 2021 as “The European Year of the Railways,” little has changed regarding the interoperability of EU railways, particularly concerning unified overhead electrification.

European Railways’ Electrification Systems

European railways’ four electric shocks

Early railway electrification efforts in the late 19th century utilized low-voltage DC systems and battery trains, drawing upon T.A. Edison’s inventions. Overhead or third-rail electrification systems with voltages in the 600 to 750 V range were subsequently adopted, but the limited power of these systems necessitated substations at close intervals, as seen with LIRR and MN in the U.S., and Network Rail in Southeast England, which uses a 750 V third rail.

Nikola Tesla’s discoveries favored AC current, leading Austro-Hungarian genius Kálmán Kandó to develop a three-phase AC system with twin overhead wires. Italy’s Valtellina saw the world’s first main line overhead electrification in 1902. This system, using medium voltage in Europe (3-3.6kV, 15, 16⅔ or 25 Hz) and high voltage on GN’s old Cascade Tunnel in the Rockies (6600 V, 25 Hz), achieved success in Italy with over 2,000 km of lines. However, its limited power output and 11 km substation spacing, as seen on the 23,5‰ steep Brennerpass line in Italy, led to its eventual conversion to 3kV DC on May 24, 1976. Some Swiss tourist lines still use this system.

The 3-phase overhead’s speed limitations prompted a shift back to DC, with 1.2-1.5kV overhead wires or, in some cases, a third rail. This was successful in The Netherlands, France, Ireland’s DART, and the S-Tøg in København, totaling roughly 8,000km. However, substations needed to be spaced less than 10 km apart on steep gradients. This system is also expensive and carries inherent dangers due to high currents.

In Germany, Austria, and Switzerland, along with Sweden and Norway later, the 15kV 16⅔ Hz single-phase AC system became the standard due to cheap hydropower. The locomotives hauled a heavy transformer. The Gotthard’s line had 26‰ grades with very tight curves. Despite the heavy locomotives, the system allowed for substations spaced 50 km apart on flatland and 30 km in mountainous regions, with 220mm² cross section overhead lines. This system required dedicated generating stations and converter substations, resulting in high costs.

Following WWI, the evolution in insulation and gears led to the success of the 3kV DC overhead in Butte Anaconda and Pacific and the ill-fated Milwaukee Road (U.S.). Italy, Belgium, and Spain followed suit, with Poland and Czechoslovakia later adopting the system. Slovenia, then part of Italy, also received 3kV DC, extending to Zagreb via Rijeka and Ljubljana. Despite the system’s initial advantages, increased traffic and high-power locomotives reduced the substation spacing on steep lines to around 10 km. In Italy, the Brenner pass line on the Italian slope has a similar number of substations as the old 3-phase. The use of 610mm² wires on some Italian high-speed lines in the seventies and eighties and 540mm² on new mountain or freight train electrifications increased costs. The intense train circulation and high currents led to rapid wear of the costly copper wires, necessitating their substitution every four or five years, involving four-hour service interruptions per 1800m section.

Finally, the 25kV, 50Hz single-phase electrification system, using “industrial frequency” power from the grid, gained popularity after WWII. This system enabled substation spacing of up to 70 km on flatland and roughly 40 km in mountainous or high-traffic areas. Countries such as France, Slovakia, and Czechia currently use dual systems, gradually converting older lines. Croatia completed the conversion of the 3kV lines ten years ago. Czechia announced its complete switchover for 2040. Other countries, like Spain, Belgium, Italy, and The Netherlands, adopted 25kV for high-speed lines, but no conversion plans exist for other lines. The Netherlands abandoned the 1.5kV= overhead in 1987, but a 2012 cost review (estimated at €10 billion) led to the project’s cancellation.

A practical way to a definitive solution (and huge energy savings!)

The current European railway network is a patchwork of electrification systems, including 1.5 and 3kV DC, 15kV 16.7 Hz, and 25kV 50 Hz overhead lines, creating electric “islands.”

The Merano-Mals line (60km) in South-Tirol, Italy, was re-opened by South-Tyrol in 2005, using renovated infrastructure and new trains. The success of the line led to the decision to electrify it with 25kV AC, which STA of Bolzano found to be cheaper to install and maintain, and to achieve an energy saving of around 33% compared to Italy’s 3kV DC system. STA’s calculations, using a commercial simulation tool, revealed that the 25kV system has an efficiency of 100%, compared to 67% for 3kV, 89% for 15kV, and 55% for 1.5kV.

Today, many new locomotives and EMUs are designed as 4-system platforms. Forty years ago, multi-system locomotives were much more expensive. It is common now to see trains (including freight trains) stopping at border stations for only one minute to change drivers or running through without stopping.

The conversion of existing lines to a unified system is expensive (more than 100.000 €/track-km). New 25kV electrifications are in the 300.000 €/km range. In Italy, the state-owned IM RFI declares a yearly energy consumption of roughly 4500 GWh. Using STA’s efficiency calculations, that figure could be reduced to 3000 GWh. STA also calculated that the wires need to be substituted each 50 years, instead of 10 years or less. STA’s investment will be repaid after roughly 12 years of electric operation.

Solutions and Future Steps

The Union should offer a 25% contribution for purchasing 2- or more system LOCs/EMUs with 25kV capability, or the conversion to 25kV capability of “young” units. The Loc&Pas and Energy TSIs should be recast to admit only 25kV capable units as compliant. The conversion of existing lines to 25kV and the new wiring of diesel routes should be contributed at 50%, with a ban for public money from the MS and the EU for new lines if not 25kV energised. The Energy TSI should be recast to allow only 25kV lines as TSI compliant.

Italy took 30 years (from 1946 to 1976, for 2,000 km) to abandon the outdated 3-phase system and fully transition to 3 kV DC. Less than 15 years later, the newly planned high-speed lines adopted the 25 kV system. In spring 2005, the second-generation high-speed Roma-Napoli line was energised and opened for testing.

The 25kV system offers practical advantages; technicians of Italy’s IM RFI developed a circuit modification to avoid ice formation during the winter. The wires of the two tracks are short-circuited together, isolated from all installations, and energised with 25kV and 700 A.

If South Tyrol’s STA move, the Fehmarn Belt new line from Puttgarden to the junction north of Lübeck (Bad Schwartau) should announce the adoption of 25kV. Germany could scrap roughly half the substations, Italy more than 65%, and The Netherlands almost 75%.

Implementation Timelines

The Czech Republic has already (2017) decided to convert the 3kV lines to 25kV; and Slovakia should follow. The 1.5kV DC islands of The Netherlands and South France could be converted in five years, eliminating this low power system. The 3kV DC islands Spain, Italy, Slovenia, Belgium, and Poland should start planning and work for the switchover of their networks as soon as possible. The completion 10 to 15 years after the 1.5kV abandonment could be a reasonable timing. Sweden should start from the South, in contact with Denmark’s 25kV system. Norway, if interested, should start from the North and the West, reaching the Oslo area and then Sweden. Germany, Austria (and non-EU Switzerland) maybe will take 25 years. The S-Bahn lines of the greater metropolitan areas (München, Stuttgart, Nürnberg, Frankfurt, Hannover, Rhein-Ruhr, Rhein-Sieg, Rhein-Neckar, Bremen, Wien, Zürich, Bern) would be addressed.

Conclusion

Achieving a unified overhead electrification system in the EU would significantly improve interoperability across the continent, representing a crucial step towards the Single European Railway Area.

Company Summary

Network Rail: This entity is responsible for the rail infrastructure in Southeast England.

FS: No further details are available in the source.

LIRR: This is the Long Island Rail Road, a commuter rail system in the United States.

MN: No further details are available in the source.

RFI: This is the state-owned infrastructure manager in Italy.

STA of Bolzano: The Infrastructure Manager in South Tyrol.

Technology

EMUs: Electric Multiple Units.

HS: High-Speed.

LOCs: Locomotives.

TEE: Trans-Europ-Express.

TSI: Technical Specifications for Interoperability.