Reliable Ultra-fast Network for Rail - RUNR™

RUNR (patent pending) is a 10/100Base-T Ethernet communications network designed to provide a high-bandwidth communications backbone across a consist of passenger rail vehicles.

The trainline (Ethernet) communicates between vehicles in the consist through an ETHERPIN. interface that provides a direct 100Base-T Ethernet connection without physical contact of coupler pins. The RUNR system propagates trainline communications between vehicles by transferring energy between two adjacent magnetic devices (ETHERPINs) in much the same way a transformer works.

When the coupler is linked the ETHERPINs operate with a normal separation of up to 3.8 mm (0.15 inches) and are not affected by dirt or other contaminants. Regular connector contacts in couplers must make physical contact and are susceptible to signal noise caused by unequal pressures on the contact made during normal movement of the vehicle. With the non-contact ETHERPINs this problem is eliminated making this system highly accurate and reliable.

Two pins are used, one for each Ethernet wire pair (one pair is TX, the other RX). These pins are backed up by a second set, providing a redundant connection through a total of four pins. See Figure 2. The Ethernet LAN connection between the ETHERPINs and the main on-board switching hub is supplied by the Trainline Interface Unit (TIU).

The Trainline Interface Unit (TIU) contains redundant electronics that provide pulse shaping circuits and Automatic Gain Control (AGC), to compensate for variations in pin separation that can occur during the manufacturing process and/or normal train coupling.

An inherent result of the RUNR design is that the effects of EMC/EMI are minimized, and it has successfully passed the typical qualification tests (shock, vibration, temperature, humidity, EMC) required for rail environments. The RUNR data rate of 100Mbps has been successfully demonstrated in functional train environments.

ETHERPIN size comparison

ETHERPIN installation in coupler

The hardware base for the trainline is a 100Base-T Ethernet LAN with all connections terminating in an Ethernet switch. The Ethernet switch increases the trainline effective throughput and flexibility, as messages are only routed to the intended subsystem rather than being broadcast to all points on the network. Each port is independent from a configuration and fault isolation perspective. This switched, route-sensitive connectivity permits network traffic within a vehicle to operate independently of network traffic that must pass to all vehicles.

This distributed processing architecture enables individual subsystems to send data to the subsystems that use that data, whether they reside in the local cab, the second cab in the same vehicle, or any other cab in a multi-car consist. A single RUNR (Ethernet) Trainline Network typically carries the required CCTV, VMS Audio, MDS, and other optional content, such as non-CCTV video, that is used by each vehicle in the consist, with significant spare bandwidth. Intelligent subsystems communicate with each other via the trainline (Ethernet) using TCP/IP and related higher layer protocols.

TIU Interface

The Trainline Interface Unit (TIU) acts as the interface between the ETHERPIN transceivers and the Switching Hub to provide: receiver equalization; signal amplification and automatic gain control, and primary/backup channel switching.

The time to establish synchronization between two Trainline Interface Units in adjacent cars can be up to eight seconds from the time the last unit is powered on. After the connection is established, recovery from a momentary loss takes as little as 200ms. Once synchronization is acquired the connection status reported to the controlling device indicates an active link.

RUNR Benefits

The RUNR system is capable of simultaneously supporting multiple subsystems that use a 10/100Base-T Ethernet LAN communications network with Internet Protocol (IP). The network is capable of handling multiple simultaneous audio and video streams so automatic announcements may coincide with a Passenger-to-Operator Intercom (POIC) and video transmission of images. Multiple video streams allow simultaneous viewing of cameras from any car on the consist. Audio announcements are multicast on the Ethernet, which means that the packets are replicated from each switch onto every segment. The advantage is that the source sends each packet only once.

The non-contact, magnetic coupled design of RUNR eliminates the signal noise problems encountered by normal electric contacts making this system highly accurate and reliable. This simplified high-bandwidth communications backbone for the interconnection of on-board systems minimizes the need for costly car wiring and manual car-to-car connections.