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Industrial Ethernet Book Issue 101 / 14
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Wireless innovations drive 21st century rail travel

Train-to-ground communication is an essential technology as transportation solutions continue to gain in sophistication and effectiveness. But wireless connectivity, in particular, is moving to the forefront as a way to implement new systems for control, passenger information and security.

THE RISING POPULATION DENSITIES of global cities and escalating environmental concerns are driving governments around the world to find new ways for improving quality of life and economic viability. Leaders are casting their eyes, and actions, toward revitalizing rail transportation to alleviate congestion and pollution of all types.


Advanced wireless networks to operate trains, manage traffic flow, monitor safety and provide enhanced connectivity so passengers can work and play onboard.

Government interest, and resulting incentives to elevate rail as a preferred mode of transportation for both goods and people, is giving rail operators greater opportunity to improve performance, expand capacity and offer differentiated service to customers through revamped communication infrastructure. Wireless networks to operate trains, manage traffic flow, monitor safety and provide enhanced connectivity so passengers can work and play onboard is vital to a rail renaissance and addressing urbanization and climate concerns.

Wireless drives innovation

Innovating train-to-ground communication is essential for the future of rail travel. The adoption of wireless connectivity will transform operations and what network engineers need to consider in network infrastructure.

Three important applications for optimizing railway networks include:

  • Communications-based train control (CBTC)
  • Passenger information systems (PIS)
  • Security systems, particularly closed-circuit televisions (CCTV) for video surveillance

Optimizing network efficiency

Until now, the primary way to increase the capacity of a rail network was to lay new track, dig tunnels or extend platforms to accommodate longer trains. Each of these approaches is costly, lengthy and highly disruptive. CBTC applications change all that,giving rail operators a breakthrough way to optimize transportation networks and increase capacity of existing infrastructure through real-time train positioning.

CBTC continuously manages the distance or time between trains (headways), as well as speed and acceleration profiles in real time, resulting in the ability to run shorter, lighter and faster trains more closely together. This increases capacity without expensive and disruptive civil engineering projects.

CBTC can also lower fuel costs by applying different driving methods, such as coasting and reduced acceleration curves during off-peak travel, optimizes energy efficiency.

At the heart of CBTC networks is the Automatic Train Supervision (ATS) system, which acts as the command-and-control center managing the traffic per specific criteria. Several subsystems provide critical communication nodes for connecting wayside and onboard points in a seamless system, for movement, safety and more.

Wayside equipment includes the subsystems that control every zone in the line or network. The wayside Automatic Train Protection (ATP) system manages communications with trains in its area and calculates the limits of movement authority for every train. The Automatic Train Operation (ATO) system provides trains with destination and dwell time in its area and may perform auxiliary tasks such as event communication or skip/ hold station commands.

Onboard equipment includes the subsystems for control of the train′s movement. The onboard ATP system controls speed and communicates with the wayside ATP system for information necessary for safe operation. The onboard ATO system is responsible for maintaining traffic regulation targets and passenger comfort - either by assisting the driver or in full automation mode.


Communications-based train control continuously manages the distance or time between trains (headways), as well as speed and acceleration profiles in real time, resulting in the ability to run shorter, lighter and faster trains more closely together.

Overcoming railway obstacles

Wireless technology is commonplace for CBTC systems, but not without challenges. Overcoming the obstacles presented by the environment and speed of moving trains for these networks requires the following characteristics:

Appropriate railway onboard vehicle certification: These pre-requisites for installation on vehicles or trackside include International Organization for Standardization (ISO) and the International Electrochemical Commission (IEC) for global use; European Standard (EN) for Europe and Association of American Railroads (AAR) and American Railway Engineering and Maintenance-of-Way Association (AERMA) for North America.

Fast, secure roaming: A roaming handover time of less than 50 ms is essential to ensure uninterrupted train-to-ground communication.

Sufficient bandwidth: A bandwidth of at least 4 Mbit/s is required to carry all data from the train to the Operation Control Center (OCC).

Network latency: To ensure real-time communication, the maximum latency on the end-to-end network must be less than 5 ms.

Security: The network should be hardened against attacks that can threaten availability and performance.

Passenger information systems

As air travel becomes increasingly stressful and expensive, well-run trains offer passengers a viable, efficient and pleasant alternative for traveling on business or for pleasure. In Europe and the United States, many major destinations are accessible in less than three hours by high-speed rail.

Passengers want trains that run on-time and when trains are delayed, they want real-time status information. Today, wireless-based Passenger Information systems provide accurate and immediate information on how passengers can manage their journey.

The technology also offers operators a revenue opportunity with location and time-based advertising on message boards - between itinerary updates and the available space on larger LCD displays. Giving customers information about services and attractions at their destination, should they be delayed during the journey, improves the overall experience.

The wireless requirements to enable the advances in PIS include:

  • Appropriate railway onboard vehicle certification: These pre-requisites for installation on vehicles or trackside include EN for Europe and AAR/AERMA for North America.
  • Sufficient bandwidth: A bandwidth of at least 5 Mbit/s is required to carry all data required for the PIS.
  • Security: The network should be hardened against malicious behavior and attacks.

Safe and secure departure-to-arrival

Video surveillance is becoming the preferred medium for meeting safety and security requirements for both operational reasons and passenger expectations. Video systems are used to monitor passenger and driver behavior, count passengers and much more. In the past, video would have been stored and then downloaded later; now though, real-time streaming supports the ability to deal with incidents as they occur.

For effective video transmission, the wireless train-to-ground communications system needs to include the characteristics cited above, as well as the Parallel Redundancy Protocol (PRP) for Ethernet networks. PRP ensures seamless transition of packets between access points without switchover effects like zero authentication delay and no/reduced quality degradation.

Time-sensitive networking for rail

Today, ensuring network availability for the transmission of critical operational and safety data from the CBTC system requires that rail operators deploy two Ethernet networks: one for critical safety data and one for other, less important information. In addition to the burdensome cost of doubling up on communications infrastructure, the approach is a customer-service nightmare - passengers often experience slow or no connectivity as priority data flow goes to operational Ethernet networks.

Time-Sensitive Networking (TSN) will change all that. TSN provides a new level of determinism in standard IEEE 802.1 and IEEE 802.3 Ethernet networks, guaranteeing on-time data transfer of high priority information from a single Ethernet network. It provides rail operators and passengers with three key benefits:

  • Expanded capacity: remote control and accurate, real-time data allows trains to run more frequently.
  • Improvedon-boardexperience: passengers expect to work and play en route; TSN allows operators to deliver that reliable connectivity, with no risk to the flow of critical, operational data.
  • Safety, first and always: passenger and operational data will never get in the way of the other or slow down the Ethernet network, so trains run safely and without disruption.

All aboard

The growing interest in rail as a viable mode of transportation presents operators with an exciting future. Meeting the demand requires that rail operators leverage advances in automation and communication technology to build operational networks that perform efficiently, reliably and safely.

A well-planned communication network strategy should be an integral part of operators′ plans. Innovations available today and in the near future in wireless-based train-to-ground communications systems make it possible to expand capacity without expensive investments in infrastructure, improve service levels and bring new customers to rail-based transportation.

Richard Weatherburn, global vertical marketing manager, transportation, at Belden.


Source: Industrial Ethernet Book Issue 101 / 14
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