If you've read more than a couple of things on here, you'll have guessed I rate Teltonika. I've been working with their kit since the early 3G routers first turned up in the UK, and I've watched the range grow up through 4G and 5G and every flavour in between, from LTE-M and NB-IoT to RedCap. So when Teltonika asked us to run a piece on LHC tunnel monitoring at CERN, I didn't need much persuading.
Most of what crosses my desk after twenty-odd years in this game is routers doing router things in roadside cabinets. This is a router riding a monorail around the Large Hadron Collider, 100 metres underground. That's a bit different, and the engineering lessons travel well beyond particle physics.
What follows is Teltonika's own write-up, which we're publishing as a guest post, lightly edited into UK English. After it, I've added a few notes on the bit the article skips over (how you get a mobile signal that far underground in the first place), followed by some background on CERN, why the LHC has just gone quiet, and a short note on Teltonika.
About this article: the main article below was supplied by Teltonika Networks and is published as a guest post. The introduction, editor's notes and the CERN background are by IoTPortal.
How does connectivity support LHC tunnel monitoring from a mobile platform?
Industrial inspection systems are increasingly moving beyond fixed sensors and manual inspection rounds. For large or hard-to-reach assets, a mobile platform offers a flexible way to collect data from many locations without permanently instrumenting every part of the monitored environment.
CERN's Large Hadron Collider (LHC) is an extreme example of this challenge. Its 27-kilometre tunnel contains critical infrastructure and equipment that must be monitored continuously, including the tunnel structure, oxygen levels and temperature. To support this, CERN developed the Train Inspection Monorail (TIM), a small autonomous vehicle that travels on a track suspended from the tunnel ceiling. TIM carries cameras and measurement equipment for monitoring the tunnel structure, oxygen percentage, communication bandwidth and temperature, and provides both visual and infrared imaging.
Collecting the data is only part of the job, though. TIM also has to move that data reliably from the tunnel to remote systems, so its communication architecture must connect several different onboard devices and make their data available on CERN's network.
Why mobile monitoring is changing industrial connectivity
CERN describes TIM as a modular platform carrying sensors for visual observation, infrared imaging and environmental sensing. It can also carry additional devices, which lets the platform adapt to different measurement tasks.
A fixed monitoring architecture needs extensive cabling, distributed power and communications infrastructure across the whole asset. A mobile platform instead brings the sensing equipment to the area being monitored, so every location no longer needs its own complete installation.
For operations and engineering leaders, this model depends on a connectivity layer that is as flexible as the mobile platform itself. TIM needed more than a wireless link: its communications system had to bring together different sensors and cameras and transmit their data to CERN's network.
Turning a mobile platform into a connected edge system
Because TIM combines different types of equipment, its network architecture has to accommodate multiple interfaces without adding unnecessary hardware to the vehicle. According to Teltonika, CERN integrated the RUT956 industrial cellular router into TIM's core, where it connects cameras and sensors and provides a 4G link to CERN's internal network.
In this configuration the router is effectively the connectivity hub of the mobile platform, aggregating data from multiple onboard devices before sending it on. The RUT956 combines LTE Cat 4 connectivity with four 10/100 Mbps Ethernet ports, RS232, RS485 and configurable digital and analogue I/O. Equipment using different physical interfaces can therefore connect through a single device, reducing the number of separate components that would otherwise need to be installed, powered and maintained.
For system integrators, the main advantage is flexibility. The network layer can accommodate a changing sensor payload without needing a separate connectivity device for each type of equipment.
Keeping a mobile platform within its power budget
Once the communications layer is treated as part of the mobile platform, its power draw becomes an important design constraint. Teltonika identifies low power consumption as a key consideration for TIM because the vehicle runs from a battery.
The RUT956 is specified for a 9-30 VDC supply, with power consumption below 2 W at idle and below 7 W at maximum. It measures 110 × 50 × 100 mm and weighs 287 g. Its specified operating temperature range is -40°C to +75°C, in an aluminium housing rated IP30.
For engineers evaluating a similar mobile system, these figures are practical design inputs. Power consumption affects the vehicle's energy budget, while dimensions, weight and operating temperature affect the physical and environmental design. The router has to be evaluated as part of the complete platform, alongside battery capacity, payload weight, mounting and environmental conditions. If you're working through the same sums on a fixed remote site, our guide to powering remote IoT covers the budgeting side.
Staying connected as the platform moves
Power isn't the only constraint. Because TIM relies on a wireless connection to make its data available remotely, keeping that connection up is an important availability consideration, particularly as the platform moves through a large and complex environment.
The RUT956 has two SIM slots with automatic switching on conditions such as weak signal, loss of network or failed data connections. This can support a redundancy strategy by letting the system move to another available network when one becomes unreliable.
Dual-SIM capability alone doesn't guarantee coverage, however. Carrier selection, antenna design and network architecture still need to be matched to the deployment environment.
Securing the connection between the platform and the network
The same connectivity that makes real-time remote monitoring possible also creates a security consideration. A mobile inspection platform connected to an organisation's internal network becomes part of its OT/IT security architecture, so connectivity and cybersecurity need to be designed together from the start.
The RUT956 provides VPN and network security features through its RutOS operating system. The right VPN configuration, access controls, network segmentation and remote-management policies, however, should be set by the organisation's own cybersecurity architecture and deployment requirements.
The router therefore forms part of the edge system's security boundary, linking equipment in the field with the organisation's wider network. For a vendor-neutral look at hardening that boundary, see our cellular router security guide.
What mobile connectivity means for industrial operations
The engineering principles behind TIM aren't limited to particle physics. CERN's Knowledge Transfer material identifies potential applications in inspection, monitoring and remote handling in hazardous environments, including autonomous monitoring of utility infrastructure.
The same challenge appears across many industries: how do you collect data from distributed or hard-to-reach assets without building unnecessarily complex permanent infrastructure?
For business and operations leaders, the value goes beyond reducing fixed infrastructure. A mobile platform can be reused across multiple locations and tasks, potentially increasing asset coverage without a dedicated sensing installation at every point, and centralising the collected data gives remote teams a consistent view of equipment and operating conditions.
For engineers, the CERN example highlights five practical considerations when designing a similar system:
| Consideration | The question to ask |
|---|---|
| Integration | Can one connectivity platform accommodate the different interfaces used by the cameras and sensors? |
| Reliability | Can the system stay connected through redundancy or failover when network conditions change? |
| Power | Does the communications equipment fit within the platform's available energy budget? |
| Environment | Do its temperature range, enclosure, dimensions and weight meet the deployment's requirements? |
| Security | Can the platform be integrated into the organisation's existing OT/IT security architecture? |
These choices directly affect deployment cost, reliability and scalability. A connectivity architecture that can accommodate different sensors and operating conditions makes the platform easier to deploy in new use cases.
CERN's TIM shows that once sensing becomes mobile and autonomous, connectivity becomes part of the machine's core architecture. The same principle applies to industrial robots, infrastructure monitoring vehicles, remote utility systems and any other platform that collects data at the edge and makes it available to operators, without bringing the entire monitoring infrastructure to the asset.
Editor's notes: how do you get 4G 100 metres underground?
Here's the bit that made me sit up. The article talks about a 4G link to CERN's network as if it's the most natural thing in the world, but the LHC sits around 100 metres below the French and Swiss countryside. No mast on the surface is getting a signal down there on its own.
The answer is leaky feeder. According to a Rohde & Schwarz case study on CERN's underground network, the tunnels are covered by roughly 60 km of leaky feeder cable fed from surface base stations and 46 underground repeater sites, carrying 2G, 3G and 4G. Leaky feeder is coaxial cable with deliberate slots in its outer shield, so it radiates and receives along its whole length. Think of it as one very long, very thin antenna running the length of the tunnel. It's the same approach used in road and rail tunnels and mines, and it's why a standard LTE router on a moving vehicle can stay connected the whole way round.
That's also the real-world answer to the article's own caveat that dual SIM doesn't guarantee coverage. TIM works because CERN built the coverage first. If you're planning a mobile platform in a tunnel, a plant room or a long industrial building, the router is the easy decision. The RF plan is where the project succeeds or fails, and it's worth surveying the route before anyone orders hardware.
My other observation is how little of this is exotic. Strip away the particle accelerator and TIM's connectivity is a battery-powered vehicle, a handful of Ethernet and serial devices, an LTE Cat 4 router, failover and a VPN back to base. Those are exactly the building blocks we see in agriculture, utilities and EV charging every week. CERN just happens to have the most interesting place to put them.
About CERN and the Large Hadron Collider
CERN, the European Organization for Nuclear Research, runs the world's largest and most powerful particle accelerator on the Franco-Swiss border near Geneva. The LHC is a 26,659-metre ring about 100 metres underground. It first circulated beam on 10 September 2008 and in July 2012 delivered the discovery it's best known for, the Higgs boson.
The numbers are hard to get your head round. The machine uses 9,593 magnets, including 1,232 dipoles that bend the beams round the ring, and they're cooled to 1.9 K (-271.3°C), which CERN points out is colder than outer space. Since 2022 it has collided protons at 13.6 TeV, the highest energy ever reached in a laboratory.
TIM itself has an interesting back story. It runs on the monorail track originally installed for the Large Electron-Positron collider (LEP), the LHC's predecessor in the same tunnel. LEP shut down in 2000 and its suspended track was reused for the new machine. CERN said in 2016 that two TIM units were working in the tunnel, and its Knowledge Transfer group now lists TIM as a commercially available technology for radiation mapping, thermal imaging, infrastructure inspection and safety monitoring, communicating over 4G or Wi-Fi.
Why has the LHC shut down?
You may have seen headlines this summer about the LHC going dark. It hasn't closed for good. Run 3 ended at the end of June 2026, and the machine has entered Long Shutdown 3 (LS3), a multi-year upgrade that turns it into the High-Luminosity LHC (HL-LHC). According to CMS, Run 3 delivered 355 inverse femtobarns of collision data to the experiment, and CERN's current schedule has the upgraded machine starting Run 4 in June 2030.
The aim of HL-LHC is many more collisions, which means more data and better odds of spotting rare events. Doing that means installing new equipment in the tunnel, including more powerful focusing magnets, new superconducting "crab cavities" and a reinforced protection system, while ATLAS and CMS rebuild large parts of their detectors.
That's where I think a project like TIM earns its keep. A shutdown on this scale means years of heavy engineering in a 27 km tunnel, and anything that lets teams check conditions, map radiation or inspect infrastructure remotely before sending people in is worth having. When the beams come back, the tunnel goes back to being a place people can't be, and remote eyes matter even more.
About Teltonika
Teltonika was founded in Vilnius, Lithuania, in 1998 by Arvydas Paukštys and is now organised as the Teltonika IoT Group, with Teltonika Networks as the division making industrial routers, gateways, switches and the RMS remote management platform. Its networking range now runs from LTE and 5G routers (including 5G RedCap) to IoT gateways, Ethernet switches, access points and embedded modules, and it sells into around 150 countries. Its work with CERN isn't new: Teltonika was already writing about supplying connectivity for CERN's robotic systems, including TIM, back in 2022.
Frequently asked questions
What is CERN's Train Inspection Monorail (TIM)?
TIM is a small autonomous vehicle that runs on a monorail track suspended from the ceiling of the LHC tunnel. It carries cameras and sensors to monitor the tunnel structure, oxygen levels, temperature and communication bandwidth, and provides visual and infrared imaging so teams can inspect the tunnel remotely.
How does TIM get a mobile signal 100 metres underground?
CERN's tunnels are covered by around 60 km of leaky feeder cable, a coaxial cable that radiates along its length, fed from surface base stations and underground repeater sites carrying 2G, 3G and 4G. TIM's onboard 4G router connects to that underground network.
Why has the Large Hadron Collider shut down?
The LHC finished Run 3 at the end of June 2026 and entered Long Shutdown 3, a multi-year upgrade to become the High-Luminosity LHC. CERN's schedule has the upgraded machine starting Run 4 in June 2030.
Sources: CERN: The Large Hadron Collider; CERN: Meet TIM, the LHC tunnel's robot; CERN Knowledge Transfer: TIM technology brief; CERN: New schedule for CERN's accelerators; CMS: The end of Run 3; Rohde & Schwarz: CERN QualiPoc case study. Product specifications supplied by Teltonika Networks.
