Rethinking the resiliency of fiber optic communications solutions in Rail 

Written by 

Antonio Sequeira

Vice President Market Manager Railway

Wireless train communication has become an integral part of modern public transportation systems, so much so it is now viewed as a differentiator between operators. Passengers have become so accustomed to reliable 24/7 connectivity in their everyday lives that they now expect that same experience when traveling on trains, with ever-faster data transmission for streaming video and other services a must. This means the worlds of communication and railway must come together to create robust, scalable, and reliable onboard communication infrastructures.  

Despite the important role tried and tested fiber optic solutions can play, the railway industry remains hesitant to use this technology on-board its rolling stock vehicles owing to concerns over its specific operating parameters. For example, a high-speed train is subject to intense mechanical stresses and high safety requirements. Yet today’s connectivity technology - and the results of field experiences - have proven that fiber optic is, and will remain, an entirely appropriate technology for the rail industry in the future.

A ‘future ready’ solution for communications 

One challenge that has traditionally plagued onboard connectivity is the electrostatic and electromagnetic signal disturbances caused by trains using distributed traction motors. Even though traditional twisted-pair copper cables are constructed with shielding, this can never perform as well in protecting against these signal disturbances as glass fibers. The ability to ensure transmission reliability at high data rates significantly contributes to Quality of Service (QoS) and system availability. 

Another attractive feature offered by fiber optic connectivity solutions is the opportunity for network scalability. With the rapid, constant evolution of communication technologies, alongside the long-life cycle of rolling-stock equipment, the longevity of any solution is always a concern. It is therefore vital that the network infrastructure installed today remains a viable solution for the next 15 years, or even longer. Replacing the network equipment with the latest technology may be a straightforward task, but when it comes to replacing the wiring infrastructure, that is an entirely different proposition.  

However, longevity is not a problem for fiber optic solutions. A single pair of fiber cores, the technology enabling the running of 1000BASE (i.e., 1 Gbit/s data rate) and 10GBASE (i.e., 10 Gbit/s data rate) operations today, could comfortably scale up to 40GBASE or even 100GBASE operations in the future without requiring any change of cabling. 

A future benefit comes with the weight-saving capabilities of fiber optic cables. An optical cable is 40 percent lighter than a Cat7 cable, reducing energy consumption or the aging of braking systems and track infrastructures. In addition, the growing trend of converging all Train Control and Management System (TCMS) functions into a single TCMS physical network would generate significant cuts in coach network wiring infrastructures and the quantity of network equipment used in the future. However, this could only be envisaged if the transmission medium can handle an increased data load and provide the reliability level expected of it – exactly what fiber optics does best. 

Delivering a solid return on investment 

The high bandwidth scalability of optical fibers means that the initial investment can be readily recouped. When it comes to installing a new communication technology, the train wiring infrastructure is often the bottleneck for any upgrade. This could mean that the cost of materials and the lost revenue during refurbishment could be prohibitive. The scalability of fiber optic solutions allows for the faster implementation of new technology, keeping the system up to date with minimal additional costs. This is crucial in today’s railway sector, driven by technological innovations and cost competitiveness.