ASTRID in tunnels: why uptime and SLA decide everything here.

Picture the situation a rescuer least wants to be in: an incident in a tunnel. A collision, a fire, smoke spreading through the tube within minutes. Drivers abandoning their vehicles. Casualties spread over hundreds of metres. And outside: a command post that needs to know what's happening inside, in order to direct teams it cannot see.

At that moment, one thing holds everything together: the emergency services' radio. In Belgium that's ASTRID — the network on which fire, police, ambulance and civil protection talk to each other. And in a tunnel, that network mustn't work 'usually'. It has to work. Every time.

Why a tunnel is the hardest environment

A tunnel combines everything that makes communication difficult in a single environment:

• Complete shielding. Concrete and steel fully block radio waves from outside. Without a dedicated installation, there's simply no signal inside.
• Length and depth. A signal has to carry hundreds of metres, sometimes kilometres, into every corner — including emergency exits and technical rooms.
• Chaos and time pressure. In an incident, every second counts. There's no time to discover that coverage drops out in the wrong place.
• Multiple teams at once. Fire crews inside, ambulance at the entrance, coordination outside — all on the same network, all at the same time.

In a tunnel, a rescuer can't see their colleague ten metres away through the smoke. The only thing connecting them is the signal. If it drops out, they work blind — and that at the most dangerous moment.

Here, uptime isn't a target. It's the mission.

For most networks, a few minutes of downtime per year is acceptable. For ASTRID in a tunnel, it isn't. The reason is confrontingly simple: you never know when that minute of downtime will coincide with the incident the system exists for.

That's why these projects revolve entirely around two concepts: uptime and SLA (Service Level Agreement). The SLA sets out in black and white how available the system must be, how quickly a fault is detected and repaired, and who is responsible for what. In a tunnel, those agreements are particularly strict — and rightly so.

Concretely, that means:

• Continuous monitoring. The system is permanently monitored, so a problem is visible before it becomes a danger — not only when an emergency service discovers it.
• Redundancy. Critical components are duplicated, so the failure of one component doesn't bring down the whole system.
• Guaranteed response times. In the event of a fault, fixed, enforceable repair deadlines apply — no 'we'll look into it soon'.
• Demonstrability. Availability is measured and reported, so the operator and the authorities can see that the standard is being met.

Where Mercuron makes the difference

This is exactly the kind of project we're built for. Delivering a tunnel installation is one thing; keeping it at the required level for years is another. And that second part is what critical infrastructure is really about.

Reliability and strict SLAs are a top priority at Mercuron, because we know what's at stake when things go wrong. We therefore approach a tunnel project not as a one-off installation, but as a long-term commitment: correctly designed, doubly secured where needed, continuously monitored, and with clear, honoured agreements on availability and repair.

Anyone can install a system that works on handover day. The real question is whether it still works just as reliably on some random wet Tuesday night, three years later, when it suddenly matters.

In short

• A tunnel is one of the hardest and most dangerous environments for emergency services — and they rely entirely on ASTRID.
• Complete shielding, length, chaos and multiple simultaneous teams make reliable coverage essential and technically demanding.
• Uptime and SLA here aren't contract details but the core: the system has to work at the moment you can't predict.
• That requires continuous monitoring, redundancy, guaranteed response times and demonstrable availability — precisely what Mercuron stands for.

A tunnel is safe as long as communication works. Our job is to ensure that certainty isn't a promise, but a measurable, guaranteed fact.

Are you working on a tunnel or infrastructure project where ASTRID coverage and strict availability are required? Get in touch for an analysis and advice — we'll look together at what's needed to meet the standard, and to keep meeting it.