Introduction

What does it take to design and build one of the most complex fibre optic networks in the world?

At CERN, scientists are exploring fundamental questions about the universe using the Large Hadron Collider (LHC)—a 27-kilometer circular particle accelerator located approximately 100 meters underground, spanning France and Switzerland.

Behind this scientific infrastructure lies a highly complex FTTX network connecting tunnels, shafts, surface facilities, and technical installations.

Designing and building such a network requires more than traditional tools. It requires a structured, data-driven approach where software plays a central role in planning and execution.

Comprehensive infographic showing the challenges and design principles of a complex fibre infrastructure project at CERN. The image combines tunnel environments, microduct architecture, blow-out/blow-in cable replacement concepts, radiation-tolerant fibre, software-driven network design, and the workflow from survey through build.
Integrated overview of fibre network design principles, microduct infrastructure, replacement strategies, and software-supported planning for complex FTTX environments.

The Challenge: A Highly Complex Underground Network

The CERN environment introduces unique constraints:

  • A 27 km circular tunnel with limited space (~3.5m diameter)
  • Deep underground infrastructure combined with surface locations
  • Multi-layer fibre architecture from ducts down to individual fibres
  • High requirements for traceability, reliability, and future adaptability

The network consists of:

  • Trenches, ducts, and microducts
  • Mini cables and fibre bundles
  • Optical Distribution Frames (ODFs) in tunnel and surface
  • Splice closures, termination modules, and patching environments

Each component must be:

  • Uniquely identifiable
  • Logically connected
  • Geographically positioned
  • Fully documented
Infographic showing key figures and statistics of a large-scale CERN FTTX infrastructure project. The image highlights one FTTX project containing 377 sub-projects, 467 plant units, 576 component types, 236 purchase orders, multiple project warehouses, store management, purchase control, and more than 80 standard reports.
Overview of the scale and complexity of the CERN FTTX project with structured project data, component management, procurement control, and reporting.

 

The Role of Software in Project Planning

Structuring Complexity from Day One

In the planning phase, software enables engineers to structure the network in a logical and scalable way:

  • Definition of all components and their relationships
  • Hierarchical modelling (duct → tube → cable → fibre)
  • Unique identification of every asset
  • Integration of technical documentation, drawings, and images

This transforms the design into a data-driven digital model, not just a drawing.

Infographic showing a structured component registration hierarchy for a fibre network environment. The diagram illustrates outdoor registration levels from trench, duct, mini tube, mini cable, fibre bundle and optical fibre, and indoor registration levels including building, room, ODF, termination modules, splice cassettes and splices.
Hierarchical component registration model providing complete visibility from civil infrastructure to individual fibre connections.

Integrated GIS and Engineering Design

A key requirement in complex environments is the integration of:

  • CAD-based engineering drawings
  • GIS-based geographic visualization
  • Logical network structure

This allows engineers to move seamlessly between:

  • Physical layout
  • Network topology
  • Geographic context

With support for most coordinate systems and real-time map alignment, the network is fully visualized within its environment.

Planning Output Becomes Execution Input

One of the most important advantages:

👉 The design is not static.

Instead, the planning data directly supports execution:

  • No duplication of data
  • No loss of detail between design and build
  • Consistent information across all project phases
Modern network management interface showing a hierarchical structure of a complex FTTX network. The screen displays tunnels, ducts, star points and handholes in a structured tree view with associated labels and network elements.
Network hierarchy view providing structured visibility of connected FTTX components and infrastructure assets.

Designing High-Density FTTX Networks with Microduct Systems

In a constrained environment like the LHC tunnel, efficient use of space is critical.

Microduct-based infrastructure enables a highly compact and flexible network design.

Microduct Architecture and Network Design

The network is built using a layered approach:

  • Primary ducts containing multiple microducts
  • Microduct bundles with multiple small tubes
  • Miniaturized fibre cables inside these tubes
  • Fibre bundles within the cables

This enables:

  • High cable density in limited space
  • Flexible and scalable network expansion
  • Reduced need for additional civil works

At the same time, it significantly increases design complexity.

Software is essential to:

  • Model the full duct → microduct → cable → fibre hierarchy
  • Track capacity at every level
  • Allocate and reserve fibres
  • Plan future expansion scenarios

Designed for Replacement in a Radiation Environment

A key reason for using microduct systems at CERN is not only density—but planned cable replacement.

Due to radiation generated by experiments, fibre cables may degrade over time. This makes periodic replacement a fundamental design requirement.

Blow-Out / Blow-In Principle

Microduct systems enable a highly efficient replacement strategy:

  • Existing cables can be blown out of the microducts
  • New cables can be blown in using the same infrastructure
  • No excavation or physical duct replacement is required

This results in:

  • Minimal operational disruption
  • Lower maintenance costs
  • Fast and controlled replacement cycles

Built-In Capacity for Future Expansion

Microduct systems also allow for spare capacity:

  • Not all microducts are used during initial deployment
  • Additional cables can be installed later when needed
  • The network can grow without new civil works

Software supports this by:

  • Tracking occupied and available microduct capacity
  • Reserving space during design
  • Supporting phased network expansion
Modern infographic showing microduct architecture and fibre network design for a complex FTTX infrastructure. The image illustrates a layered network hierarchy from primary ducts and microducts to mini cables and fibre bundles, including software-based capacity planning, cable replacement using blow-out/blow-in principles, and spare capacity for future network expansion.
Microduct-based fibre infrastructure with hierarchical design, software-driven planning, cable replacement strategy, and built-in capacity for future network growth.

Designing for Extreme Environments: Radiation-Tolerant Fibre

The CERN environment introduces an additional challenge: radiation.

The Impact of Radiation on Fibre Optics

In radiation-exposed areas, fibre optics can experience:

  • Radiation-Induced Attenuation (RIA)
  • Increased signal loss over time
  • Material changes within the fibre

This makes standard telecom fibre unsuitable for long-term use in certain areas.

Specialized Fibre Design and Testing

Extensive testing has shown that specific fibre types can maintain performance even under high radiation exposure.

Key characteristics include:

  • Low attenuation at high radiation levels
  • Stable long-term performance
  • Suitability for long-distance deployment

These fibres can be installed using microduct systems, allowing both flexibility and durability.

Technical network diagram showing a fibre infrastructure layout between underground and surface environments. The image illustrates ODF locations, ducts, mini cables, splice closures, shafts, tunnels, and interconnected fibre pathways between multiple network locations.
Schematic representation of a layered FTTX network showing fibre connectivity, microduct routing, and underground-to-surface infrastructure relationships.

Implications for Network Design Software

The use of specialized fibre introduces additional complexity:

  • Multiple cable types with different characteristics
  • Location-based constraints (radiation vs non-radiation zones)
  • Lifecycle planning for degradation and replacement

Software enables:

  • Detailed component specification management
  • Linking fibre types to routes and environments
  • Storage of technical data and test results
  • Integration with maintenance planning
Modern schematic route visualization showing a fibre network path through interconnected infrastructure components. The diagram illustrates the logical route from a network start point through ducts, cable pathways, and fibre components to a final network location.
Route schematic providing a structured view of fibre connectivity and network component relationships.

The Role of Software in Project Execution

Managing Activities and Workflows

During execution, software supports:

  • Structured project activities
  • Task dependencies and progress tracking
  • Alignment between engineering and field operations

Material and Logistics Control

Execution also requires control over:

  • Materials and components
  • Purchase orders and deliveries
  • Installation tracking

This ensures:

  • Cost control
  • Accurate deployment
  • Reliable as-built data

Fibre Management and Traceability

Software enables full network visibility:

  • End-to-end fibre tracing
  • Multiple visualization formats (GIS, schematic, logical)
  • Integration of measurement data (e.g. OTDR)

This allows engineers to:

  • Understand connectivity instantly
  • Troubleshoot efficiently
  • Validate the network
Modern network route management interface displaying a structured route table with linked network components and a geographic route visualization. The screen shows fibre infrastructure elements, route details, and GIS mapping of network connectivity between locations.
Combined route management and GIS visualization providing complete visibility of network connectivity and infrastructure paths.

From complete Network Management to Focused Engineering Expertise

At CERN, the ITSimplicity software supported the design, planning and building of the network, including inventory and project management.

This proved that an integrated platform can manage even the most complex infrastructure.

Today’s Focus: Survey, Design and Build

Today, ITSimplicity focuses on the phases where the highest value is created:

  • Survey – accurate field data as the foundation
  • Design (HLD / LLD) – scalable and buildable network architecture
  • Build support – alignment between design and execution

Instead of maintaining inventory systems, the focus is on delivering:

👉 high-quality, execution-ready network designs

Why This Focus Matters

In FTTH and FTTX projects:

  • Poor survey leads to delays
  • Weak design leads to inefficiencies
  • Misalignment with construction leads to errors

By focusing on survey, design, and build:

  • Projects are delivered faster
  • Designs are more accurate
  • Execution is more reliable

Proven in Complex Environments

The experience gained at CERN remains highly relevant:

  • Designing in constrained environments
  • Managing multi-layer fibre infrastructure
  • Planning for replacement and expansion

This expertise is directly applicable to modern FTTH deployments.

Open Integration with Operator Systems

The current approach ensures:

  • Compatibility with operator systems
  • Integration with GIS and asset platforms
  • No vendor lock-in

Clients benefit from:

  • High-quality engineering
  • Flexibility in system choice
  • Future-proof network design

Summary

Modern FTTX networks require more than physical infrastructure. They require structured engineering, scalable design, and efficient execution processes.

Complex environments such as CERN demonstrate how fibre networks benefit from:

  • Integrated design workflows
  • Microduct-based infrastructure planning
  • Lifecycle strategies for replacement and expansion
  • Accurate survey and execution support

Today, ITSimplicity applies these principles to modern FTTH and FTTX projects by focusing on:

  • Survey
  • HLD / LLD design
  • Build support

From highly specialized scientific environments to large-scale FTTH rollouts, successful projects start with accurate data, intelligent design, and controlled execution.

Wide-angle view inside the CERN Large Hadron Collider tunnel showing underground technical infrastructure, accelerator equipment, cable trays, piping systems, and the tunnel environment extending over a long distance.
Underground tunnel environment at CERN showing large-scale scientific and technical infrastructure supporting the Large Hadron Collider.
Modern geographic overview map of the CERN area showing the Large Hadron Collider (LHC) tunnel infrastructure across France and Switzerland. The map displays tunnel routes, access points, country borders, and the relationship between the CERN campus and surrounding regions.
Geographic visualization of the CERN region and the Large Hadron Collider tunnel network across France and Switzerland.