The National Commission of Markets and Competition (CNMC) has published a report that analyzes the technical barriers that condition the provision of railway services in Spain and that limit the competitiveness of the railway, especially in the field of freight transport. The document, dated March 12, 2026, identifies four main obstacles: the coexistence of different track gauges, the fragmentation of the electrification system, the complexity of deploying the European signaling system ERTMS, and the difficulties in the rolling stock authorization process.
The report is framed in the context of European legislation that promotes the interoperability of the railway system in the European Union. Regulation 2024/1679 establishes the implementation of an interoperable European network with standard gauge (1.435 mm), complete electrification, and the ERTMS system in the corridors of the Trans-European Transport Network (TEN-T), which in Spain include the Atlantic Corridor and the Mediterranean Corridor. The Atlantic Corridor, with 6,044 kilometers of national route, connects Huelva and Algeciras with Vigo and La Coruña, linking with Portugal and France to reach Germany through the Irún border. The Mediterranean Corridor, with 4,045 kilometers in Spanish territory, connects Algeciras and Almería with Madrid, Valencia, Barcelona, and the French border through Portbou and the Le Perthus tunnel. Algeciras thus appears as a starting node in both trans-European corridors, highlighting the strategic relevance of railway connectivity in the Campo de Gibraltar within the context of the European network.
The General Interest Railway Network (RFIG) has 15,673 kilometers of lines as of January 1, 2025. The Iberian gauge (1,668 mm) predominates in the network, with about 11,050 kilometers, representing 70.5% of the total. The standard gauge adds 3,104 kilometers, mostly coinciding with the high-speed network, and there are 326 kilometers of mixed gauge, which combine both gauges on the same track with three tracks. ADIF manages 11,672 kilometers and ADIF High Speed 3,981 kilometers.
The CNMC indicates that the expansion of the standard gauge high-speed network, although conceived to facilitate international traffic, has generated internal barriers to domestic traffic. In passenger transport, there is the technical solution of variable gauge trains, manufactured by Talgo and CAF, which allow operation on both gauges. However, only Talgo has trains certified at 300 km/h with adjustable wheelsets, limiting operators' options. The network has 16 gauge changers that, according to the report, reduce infrastructure capacity by increasing travel times and constitute bottlenecks in corridors such as Madrid-Galicia or Madrid-Cádiz/Huelva. Currently, while international high-speed services between Spain and France are limited to about 8 daily, 91 daily services of domestic passenger traffic must pass through gauge changers.
In freight transport, the situation is more restrictive. Unlike passenger traffic, there is no operational gauge-changing system at a commercial level for freight, so rolling stock can only operate on one gauge, either Iberian or standard. The only solution to cross the border between both networks is to transfer the cargo, complicating the effective use of rolling stock and the design of routes that avoid empty trips—the so-called triangulations—and may make road transport more competitive for the domestic part of international traffic. Currently, only freight traffic between Barcelona and the French border through the Le Perthus tunnel (150 km), from the Port of Barcelona to Mollet (49.6 km), and from Girona to Figueres (41.3 km) operates on standard gauge.
The report warns that the planned migration from Iberian gauge to standard gauge in the Castellón-Vandellós-Vila Seca section of the Mediterranean Corridor will leave freight transport without an alternative on Iberian gauge. Railway companies have already acquired 37 locomotives on standard gauge to adapt to the change, but these will not be able to operate on the rest of the Iberian gauge network. The CNMC requests that the gauge migration study planned in the European Regulation be published as soon as possible, including an analysis of the impact on the competitiveness of railway transport and the alternative of adapting the infrastructure with mixed gauge.
Regarding electrification, 67% of the RFIG is electrified, above the European average (57%). The Iberian gauge network generally operates at 3 kV of direct current, while the standard gauge network and new electrifications operate at 25 kV of alternating current. This diversity of voltages requires the use of dual-voltage or tri-voltage locomotives, the number of which is limited, resulting in 2024 still having 27% of freight train-kilometers on electrified lines using diesel traction, a more expensive option with higher emissions. The electrification program of ADIF and ADIF AV, endowed with 900 million euros, plans to electrify an additional 1,300 kilometers before 2030. Among the included sections is the Bobadilla-Algeciras line, with 176 kilometers, a particularly relevant action for the railway connectivity of the Port of Algeciras and the entire Campo de Gibraltar, which currently operates without electrification in this corridor. The CNMC recommends planning these actions to avoid the coexistence of different voltages on the same route and coordinate them with the availability of adapted rolling stock.
In signaling matters, approximately 3,000 kilometers of the RFIG are equipped with the ERTMS system, placing Spain among the leading countries in its implementation. However, meeting the requirements of the European Regulation implies installing ERTMS on about 8,000 additional kilometers. Of the approximately 1,700 trains that operate on the Spanish network, only 563 (33%) have this system installed. The deployment also presents technical complexities arising from the existence of several versions of the system, requiring costly compatibility tests between the onboard equipment and the version installed in each section, at a cost ranging from 100,000 to 500,000 euros per test. The final version of the report also states that the Antequera-Algeciras section is one of the cases where it is planned to combine the installation of ERTMS with the change to standard or mixed gauge.
The CNMC makes six main recommendations: publish the infrastructure adaptation plans as soon as possible; analyze in depth the impact of the gauge migration before making decisions; plan electrification minimizing the coexistence of voltages; coordinate investments in ERTMS with the gauge change and deployments in France and Portugal; facilitate the installation of the ERTMS in the rolling stock while planning the removal of the inherited signaling systems; and accelerate the compatibility tests of rolling stock, whose legal deadline of three months is rarely met according to railway companies.
The report was submitted to public consultation in September 2025 and received contributions from ADIF, RENFE, IRYO, OUIGO, the State Agency for Railway Safety, the General Directorate of the Railway Sector, the Association of Private Railway Companies, FAPROVE, the Port Authority of Marín and Ría de Pontevedra, among others. The operators OUIGO, IRYO, and a rolling stock manufacturer agreed in warning that the uncertainty about the gauge migration timeline, the unification of the electrification system, and the implementation of ERTMS complicates decision-making on strategic investments. FAPROVE warned that exclusive standard gauge sections harm the continuity of freight transport, while the Port Authority of Marín requested that any migration in the Pontevedra-Ourense-Zamora axis guarantee the continuity of railway port services on Iberian gauge.