TSI stands for Technical Specifications for Interoperability. TSIs establish technical and operational requirements for railway subsystems and interoperability constituents within the European railway system.

They support interoperability by defining common requirements for areas such as infrastructure, rolling stock, energy, control-command and signalling, operations, accessibility, tunnel safety and noise.

For railway projects falling within their scope, applicable TSIs are considered during design, verification, assessment and authorisation. They help ensure that infrastructure, trains and railway systems developed by different organisations can operate safely and compatibly across the relevant railway network.

Where It Is Used:
European railway projects, particularly during railway design, system integration, compliance assessment, verification and authorisation of infrastructure, rolling stock and railway systems.

Example in Railway Context:
A new railway line may need to demonstrate compliance with applicable TSIs for infrastructure, energy and control-command and signalling, while the rolling stock operating on the route may be assessed against the relevant rolling-stock TSI requirements.

mainline, high_speed, metro, light_rail, freight

Directive (EU) 2016/797 — Interoperability of the rail system within the European Union.
Technical Specifications for Interoperability (TSIs) — European Commission implementing regulations establishing requirements for specific railway subsystems.
ERA – European Union Agency for Railways — Technical guidance, application guides and information relating to TSIs and railway interoperability.
Infrastructure TSI (INF TSI) — Requirements applicable to the infrastructure subsystem.
Energy TSI (ENE TSI) — Requirements applicable to the railway energy subsystem.
Control-Command and Signalling TSI (CCS TSI) — Requirements for control-command and signalling, including ERTMS-related provisions.
Locomotives and Passenger Rolling Stock TSI (LOC&PAS TSI) — Requirements applicable to locomotives and passenger rolling stock.
Safety in Railway Tunnels TSI (SRT TSI) — Requirements concerning railway tunnel safety.
Persons with Disabilities and Persons with Reduced Mobility TSI (PRM TSI) — Accessibility requirements for the railway system.
Noise TSI (NOI TSI) — Requirements concerning railway rolling-stock noise.