How fibre optic sensing from Bandweaver offers real-time heat detection in tunnels, helping operators act early before smoke or flames threaten life and structural integrity
Imagine you’re driving through a long tunnel when traffic starts to slow and suddenly, smoke fills the air.
The tunnel becomes a trap, heat intensifying as toxic gases replace oxygen.
Will emergency responders reach you in time?
Tunnel fires can reach 1,000°C in under five minutes, hot enough to melt vehicles.
With limited exits, toxic gases, and unpredictable smoke, detection delay can be fatal.
This leads us to question: are fire detection systems reacting fast enough?
Richard Kluth, Managing Director at Bandweaver Technologies, offers an answer, exploring the unique perils of tunnel fires, the shortcomings of conventional detection systems, and the life-saving potential of cutting-edge detection systems.
Specialising in fibre optic monitoring systems for both fire and security, Bandweaver’s expertise has played a key role in safeguarding infrastructure across the globe with fast detection systems.
The danger of tunnel fires
Tunnel fires are not as rare as you might imagine, in London alone the Fire Brigade attended 458 tunnel fires over the past decade.
Between 2012 and 2023, emergency services responded to 439 tunnel fires across Switzerland, Germany, and Austria, most involving vehicles, with 183 injuries mainly from smoke inhalation.
Major incidents like the Mont Blanc road tunnel fire of 1999 that left 39 dead, the Tauern Tunnel fire on May 29th 1999 that left 12 dead and over 40 injured, and the Gotthard road tunnel fire in 2001 that burned for 37 hours and killed 11 people, have brought tunnel fire safety into sharp focus.
Tunnel fires are especially deadly due to their confined structure and intense heat build-up.
The heat release rate of vehicles in enclosed spaces is up to four times higher than in open air, compromising structural integrity.
Poor ventilation can cause smoke backlayering, where hot gases travel against airflow, filling escape routes and hindering rescue efforts.
Fires also release toxic gases like carbon monoxide and hydrogen cyanide, reducing visibility and increasing suffocation risk.
Risks of flashover and the trench effect (where tunnel geometry channels heat and smoke) accelerate fire spread.
Combined with limited exits and access for emergency crews, these factors make tunnel fires complex and hazardous to control.
When fire strikes, time is of the essence
Traditional fire detection systems can take 2-5 minutes to trigger an alarm; when comparing this to a timeline of fire escalation in a tunnel, the results are concerning:
1 Minute: A vehicle catches fire, building up heat without triggering an alarm.
3 Minutes: Thick clouds of smoke spread, making evacuation difficult.
5 Minutes: Flames engulf the tunnel; visibility drops to zero, and the fatalities are certain.
What if fire detection had happened at 30 seconds?
The Gleinalm Tunnel fire of 2018 is a prime example.
Advanced safety systems enabled a swift emergency response – within seconds, the system alerted operators to the fire, enabling immediate response.
Emergency services evacuated the tunnel safely, with only 3 people suffering from smoke inhalation.
Whilst the tunnel still needed repairs to strengthen sections of the tunnel, the damage was reduced and there was an absence of fatalities.
The shortcomings of traditional fire detection
Traditional fire detection systems often fall short in tunnel fires.
In the 2014 Yanhou Tunnel fire in Shanxi Province, China, no properly functioning smoke detectors were in place, so no alarms were triggered.
The fire spread rapidly, causing extensive damage, and claimed 40 lives.
Smoke detectors allow fires to escalate before alerting emergency services, as they rely on smoke physically reaching the sensor, an issue made worse by back layering, where smoke moves unpredictably against airflow.
These systems are also prone to false alarms and failures in harsh tunnel environments.
“They get clogged up and dirty,” explains Richard Kluth, Managing Director at Bandweaver.
“Beams, cameras, aspirating detectors – all these systems struggle where there’s dust or fumes.”
And it’s not just dust.
Exhaust emissions, humidity, and airborne particles can compromise system accuracy or trigger unnecessary shutdowns.
Meanwhile, systems relying on flame visibility or thermal imaging activate only once a fire has already reached a critical stage.
An effective solution – smarter detection, sooner
To combat the rapid escalation of tunnel fires, early detection is critical.
That’s where fibre optic linear heat detection, like Bandweaver’s FireLaser system, stands out.
Unlike traditional systems that rely on smoke, flame visibility or air sampling, fibre optic sensing monitors temperature changes continuously along the length of the cable without needing in-field power or relying on airflow or visibility.
“It just senses heat, and it senses it fast,” explains Richard Kluth, Managing Director at Bandweaver.
“It’s a single unit and a cable, no in-field comms, no maintenance. You install it, and 15 years later it’s still working.”
FireLaser detects the earliest stages of a fire within seconds, with metre-level accuracy, even in harsh environments that disable conventional detectors.
But more importantly, says Kluth, “It doesn’t just spot heat; it identifies whether the threat is growing rapidly or rising abnormally, even before flames appear.
“We’ve seen how impactful this is in the real world.”
He recalls one instance in Turkey: “It had only risen by seven degrees, but the system flagged it.
“When they checked, the bearing was glowing red. If they hadn’t shut it down, it would have been a fire.
“Tens of millions in potential damage was avoided.”
Bandweaver has now supplied FireLaser for 250 tunnel projects and installed over 1,000 systems in road and rail tunnels.
In Italy’s Santa Lucia tunnel, FireLaser was the only system precise enough to trigger a single sprinkler over a 10-metre zone.
“Traditional systems might activate 20 or 30 sprinklers,” says Kluth.
“We only trigger one. That’s better for safety, but also for minimising damage.”
Changing times and technology
Despite its proven performance and long-standing presence in critical infrastructure, fibre optic remains underutilised in much of the fire safety sector, largely due to lack of awareness, outdated regulations, and mindset, not evidence.
Bandweaver estimates fire detection now accounts for 30–50% of its business.
While growth in tunnel projects remains steady, often tied to new construction or system upgrades, the technology is now standard in most new tunnels over 1 kilometre.
“Adoption often follows a failure, incident, or regulatory change.
But in markets like the UK, where regulations haven’t evolved, uptake lags,” says Kluth, highlighting two major car park fires[1], where no modern detection systems were in place; “In the UK, standards for car parks still date back to 1968.
Cars today are larger, closer together, and contain much higher fire loads.
Originally the guidance around car park design was based on the assumption that the fire wouldn’t spread beyond one or two vehicles.
The fire loads have changed; our standards haven’t.”
This regulatory standstill challenges systems like FireLaser, which often exceed current requirements but fall outside legacy approval frameworks.
Still, adoption is growing, driven by forward-thinking consultants and operators who recognise the value of fibre optic LHD.
Bandweaver’s partners play a crucial role, guiding clients toward risk-based, performance-driven solutions that bridge the gap between compliance and best practice.
“The biggest barrier is that people just haven’t looked at Fiber optic LHD in years.
When they do, they realise it’s cheaper, smarter and easier to use than it used to be,” observed Kluth.
As pressure mounts to improve fire safety, the opportunity for Bandweaver and its partners to lead that change has never been greater.
A smarter, safer future
Perhaps the biggest shift in fire detection is mindset.
It’s no longer enough to simply know a fire has started; operators need to know exactly where, how fast, and how severely it’s spreading.
According to Richard Kluth, that’s where fibre optic LHD transforms the game.
“Compared to conventional detectors, which are basically on-off switches, this is intelligent infrastructure,” he explains.
“It tells you where the fire is, how hot it is, how it’s spreading – and you can use that data to control ventilation, lighting and suppression.”
As regulations begin to catch up with modern risks, Kluth urges decision-makers to rethink outdated assumptions, especially around cost.
“Just averting one incident pays for the system 100 times over, if we look at the Kings Dock Car Park in Liverpool the damage was £20 million. Early detection could have prevented that” he says.
Looking ahead, Kluth sees fire detection becoming increasingly integrated with AI and smart automation.
“It’s really about combining technologies,” he adds.
“And the artificial intelligence behind that is only going to keep growing.
“Automatic firefighting will become much more focused and effective.
“People will start to realise that with this level of automation, the decision-making and detection are just so much better than they used to be.
“However, there has to be investment and this still isn’t happening.
“We can see with Luton Airport car park, which was built as recently as 2019 but was designed without modern detection or suppression systems.”
[1] Kings Dock Fire Liverpool – 31-12-2017 & Luton Airport 10-10-2023