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When Rolling Stock Shows Its Age: Replace or Refurbish?

Although rolling stock is always built to last, the time will eventually come when it either needs to be replaced or refurbished. Deciding which option to take, and when to take it, requires careful planning and involves a number of important criteria.

Safety is certainly first and foremost in every train engineer’s mind, and in this regard, you will likely need to re-engineer your system to meet the requirements of one of the newer signaling system standards. ERTMS, for example, is on its way to becoming a global standard of onboard and wayside signaling for commuter and intercity trains, and CBTC is a popular technology for metro rail systems.

Service is another issue that requires careful consideration. Enhancing passenger comfort and satisfaction could involve upgrades to onboard passenger Wi-Fi, entertainment systems, passenger information systems, and onboard CCTV, any of which could require a major overhaul of your onboard TCMS (Train Control and Management System).

Maintenance is also important, particularly for train operators, with onboard condition monitoring systems receiving a lot of attention in recent years. Thanks to the new technologies used by such systems, including Ethernet, 3G, LTE, and computer-based controllers, train operators can now know every detail of a train’s status at any time.

Challenges of Refurbishment

Refurbishing older trains is challenging for several reasons. Space limitations are a concern since older trains were not designed for the newer applications and equipment you’ll want to use. Finding a way to increase the communications bandwidth in the train is also important, since older solutions like Lonworks, CAN, MVB, WTB, and Modbus support transmission rates of at most 1.5 Mbps, which is hardly fast enough for a modern IP network. Since most maintenance engineers are hindered by a lack of knowledge of new technology, you will want to identify easy-to-use solutions that can greatly reduce the learning curve. Identifying high quality, cost-effective products is also important, since most operators are constrained by a limited budget.

Which Technologies Are Right for Your Project?

As more and more new technologies are offered to the railway market, train operators need to know how to combine these new technologies with older systems to enhance operation and service quality.

IP-based train backbone options

Leveraging an existing 2-wire infrastructure to build an IP-based train backbone is a major challenge due to the limited number of connector pins in the coupler, and limited amount of existing cables and cabling space. Options to consider include standard Ethernet, VDSL (Very high bit rate DSL), 2-wire Ethernet, and PLC (Power Line Communication), with 2-wire Ethernet and PLC two of the best options available.

Interoperability with existing systems

In refurbishment projects, the best strategy is to build up a whole new IP network infrastructure. This not only provides more bandwidth but also avoids interference problems. The figure shows a hybrid architecture for an onboard communication system. The blue area is a new IP-based network and the green area is the existing train control network. The platform should be able to interface with existing legacy buses such as CAN, MVB, or WTB.

Collecting extra signals to monitor train status

In some cases, it is difficult to collect data from the existing train bus or legacy devices. You may need to add extra sensors to collect physical signals such as temperature, door status, and HVAC status. The platform you choose will need to include I/O modules to meet these requirements.

Connection to new IP-based devices

Today, it’s increasingly common for onboard equipment to use an IP interface. For example, IP cameras, panel PCs, HMI, VoIP intercom, and LED displays. The platform should have a dedicated network switch module for connecting those IP-based devices.

Compact design

OEM systems commonly use standard 19-inch racks for all equipment. However, this is not common practice for refurbishment projects, since older trains have limited space available for installing large pieces of equipment. For this reason, your system integrator will need to identify suitable compact devices for the refurbishment project.

Moxa Solutions for Refurbished Trains

Moxa’s ioPAC 8000 series of modular RTU controllers offers serial, I/O, and Ethernet as an “all-in-one” solution in one compact platform/device. The ioPAC 8000’s unique 2-wire Ethernet technology allows system integrators to deploy Ethernet IP networks on an existing 2-wire architecture to support the 100 Mbps network currently available on refurbished trains.

In addition, Auto Carriage Sequencing (ACS) is a key feature of Moxa’s ioPAC 8600. Since systems on refurbished trains run on a daisy chain network topology that uses CAN bus or RS-485, when switching to an IP-based network, the auto carriage sequencing function is not easy to duplicate. Moxa has overcome this challenge by providing a product that can continue to perform ACS functions on the new IP-network. This key breakthrough will greatly reduce the effort required by the system integrator.

More Info

Download our newest white paper, Adding New Technology to Get the Most out of Old Rolling Stock, or visit Moxa’s website at www.moxa.com/rail for product details. You may also subscribe to our railway newsletter at www.moxa.com/railnews to stay up-to-date with the latest railway trends and learn about Moxa’s newest IP-based solutions for railway applications.

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