Level 2 specification
NR/L2/TEL/30400/002
GSM-R Availability Assessment for ETCS Traffic
Issue 1, 05 September 2026 · GSM-R & radio
How an ETCS project assesses whether the GSM-R and FTN infrastructure is available/reliable enough for ETCS — availability model, apportionment model against delay-minute targets, and the interfaces with DDaT, performance modellers, signalling and the Route
Clause map — what each clause deals with
| 1 | Purpose | Design-stage guidance for setting the telecoms availability requirements that ETCS needs |
| 2 | Scope | Methodology and criteria for availability and apportionment of telecoms infrastructure along a line of route |
| 3 | Roles and Responsibilities | RACI for the availability assessment — project, DDaT, performance modelling team, signalling, Route |
| 4 | Definitions | Points to NR/L2/TEL/30400 for terms |
| 5.1 | Introduction | Checking the infrastructure against the route's business performance targets |
| 5.2 | Availability Model | Quantitative model (e.g. reliability block diagrams) of GSM-R and FTN resilience, with scenarios and configurations |
| 5.3 | Apportionment Model | Translating predicted failure rates into delay minutes where the route has a delay-minute target |
| 6.1 | Introduction | Availability is never assessed in isolation from the key interfaces below |
| 6.2 | Digital Data and Technology Telecoms Operations | DDaT receives the availability requirements and proposes infrastructure options |
| 6.3 | Performance Modelling Team | The project appoints a qualified performance modelling team (e.g. Systems Engineering – Reliability) |
| 6.4 | Signalling Team | Signalling design constraints fed to the project and DDaT |
| 6.5 | The Route | The Route is shown how availability affects delay minutes and the benefit of alternative architectures |