Rethinking digital signalling, part A: ETCS Level 1 as a strategic choice
By David Ashby, Technical Director
For many railways, digital signalling decisions are framed as a binary choice.
At one extreme sits ETCS Level 2: attractive politically and strategically, and aligned with long‑term digital aspirations, but often challenging on cost, delivery risk, telecoms dependency, and organisational readiness. At the other extreme sits conventional signalling renewal: familiar and lower risk in the short term, but offering limited capacity benefit and little future optionality.
Yet many railways sit uncomfortably between these positions. Level 2 can feel like over engineering; conventional renewal can feel like locking in obsolescence.
This is where re‑examining ETCS Level 1 becomes interesting as a capacity increasing, future‑ready digital control system, engineered intentionally rather than inherited or overlayed by default.
The case for intentionally engineered ETCS Level 1
We often mistake ETCS Level 1 for a legacy system we have no choice in inheriting. But the specifications show a different track. With semicontinuous infill, lineside signals are no longer a hard requirement, with standards and reference architectures even illustrating signals as optional configurations.
Level 1 can function operationally like Level 2, minus radio block centres, continuous telecoms or a full GSM‑R / FRMCS dependency.
In a deliberately engineered ETCS Level 1 Higher Capacity (L1-HC) architecture:
Cab signalling becomes the primary movement authority.
Marker boards and well‑placed balises replace conventional signals.
Movement authorities are generated directly by the interlocking.
Infill and decision‑point balise placement prevents premature braking commitment and at the same time forms a safety backbone,.
A simple “Movement Authority Available” indicator supports degraded operation.
The result is not a compromise system, but a proportional one: capable of delivering a large share of Level 2’s operational benefits on the kinds of routes where capacity is driven by stations and block layout rather than line speed.
Read part B: Implementing ETCS Level 1 Higher Capacity
Is your network trapped between two extremes? It might be time to reopen the decision space. Contact David Ashby to explore how L1-HC can offer a credible, future-ready alternative.