Rethinking digital signalling: an alternative approach to ETCS Level 2 deployment
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 digital aspirations, but often challenging on cost, telecoms dependency, and organisational readiness. At the other extreme sits conventional signalling renewal: familiar and lower risk in the short term, but limited capacity benefit and little future proofing.
Yet many railways sit uncomfortably between these positions. Full Level 2 can feel like over engineering; conventional renewal can feel like locking in obsolescence. However this binary framing misses this fundamental question: do we need all elements of Level 2 in place before we begin operating the digital railway?
Decoupling ETCS: operating model vs communication layer
ETCS is often treated as a monolithic system. In practice, it can be understood as two separable elements:
Operating model: Movement Authority (MA) based control; cab signalling; and signal-free operation
Communication layer: continuous transmission (radio via RBC)
Level 2 combines both: MA-based operation and continuous communication via radio. However this coupling is not fundamental: what if the operating model of Level 2 could be deployed independently of continuous radio. This observation opens up a different way of thinking about digital signalling deployment.
Radio-free ETCS Level 2
In this configuration, the train operation follows Level 2 principles. Lineside signals are removed, MA becomes the primary control mechanism and marker boards provide physical reference, supported by a simple “MA available” indication. MAs are transmitted intermittently via balises. No continuous radio bearer or RBC is required for normal operation.
This is not a variant of Level 1 made to mimic Level 2 performance. It’s a standard architecture-aligned application of the Level 2 operating model, with the communication layer implemented through intermittent transmission rather than continuous radio.
Benefits of a decoupled Level 2 deployment strategy
Reframing ETCS in this way unlocks a set of tangible operational and strategic benefits:
1.Deploy ETCS sooner, not later:
Stop waiting for telecoms programmes to catch up.
Start implementing ETCS where signalling renewals demand action today.
Put drivers into the digital railway early in the programme: cab signalling, MA, and in-cab supervision are introduced years earlier, not at the end.
2.Remove lineside signals earlier and avoid replacing them:
Eliminate life-expired signalling assets instead of renewing them.
Shift immediately toward a lower-maintenance, higher-reliability railway.
De-risk the programme by breaking the dependency chain: first, change how the railway operates, then upgrade how it communicates. Not everything has to be delivered in one high-risk step.
3.Unlock benefits now, not in a decade:
Gain immediate access to Movement Authority-based control; removal of restrictive signal sighting constraints; and improved braking curve supervision.
Turn Level 2 into a manageable, phased migration, not a cliff edge
Strengthen the business case by bringing froward the benefits and spreading the investment, thus reducing peak funding pressure.
Don’t think of decoupling Level 2 as a compromise, but a shortcut. It’s a lower-risk route to the same destination that lets you start your digital transition today, rather than waiting for everyone else to catch up.
Instead of waiting for the perfect moment to deploy ETCS, you can begin today. Contact David Ashby to explore how rethinking Level 2 can offer a credible, faster way to a digital railway.