KV_Railway-Signaling-1

Railway Signaling


Safety is the railway signaling objective

Railway signaling is used to control railway traffic, to prevent trains from colliding and to adjust distance and the speed for proper braking time and management of tracks. Today, ERTMS/ETCS is the most advanced management, control and protection system of rail traffic and related signaling on board. The future trend will be the introduction of ever greater dynamic systems that require increasingly faster responses, real-time communication and a growing availability of wireless and wired technologies.

Increase the operational efficiency of the infrastructure

Over the next years there will be an increasing number of inhabitants and a flow of people in transit in big cities. At the same time fuel costs will rise. Therefore, it is expected that the number of passenger trains will rise by 70%. To support this increase, the infrastructure needs to develop more capacity and systems need to become faster, embracing an Ethernet and IP architecture able to replace the old networking technologies.

Internationally recognized network standards for ERTMS-ECTS

By 2015, most of the incompatible national train control systems will be replaced by a single European Control Train System. This implies a willingness to use standards to unify the infrastructure at a European level and enable the interoperability of the vectors. This leads to reliance on high-tech and high quality products based on recognized international standards - even better if these are guaranteed by IRIS Certification.

Renewing the infrastructure reducing costs of maintenance and network management

There is a need to simplify the processes of activation and to reduce maintenance costs, by decreasing the number of operations in the field, increasing efficiency, ensuring operational safety, with every possible element of risk calculated, and to reduce any service interruptions, a source of huge economic losses for railway companies. This is leading to a renewal of railway networks exclusively based on the highest experience, reliability and flexibility criteria.

Where can I find copies of the test reports for testing against European standards (such as EN45545, EN50155 and EN50121) for your products?


Copies of detailed test results as required for certification against external standards are not held on our publically accessible internet site. If you would like to see copies of these test results for a specific reason, please contact either your local Sales Representative, or venlo.salesinfo@belden.com


How many switches can be put in an MRP or RSTP ring?


MRP: 50+. Switches based on ring topology. Recovery time is almost independent of the number of switches in the ring


RSTP: up to 40 Switches for any type of topology. Because RSTP works in a hop-by-hop principle, recovery time will almost linearly increase with the number of switches in the ring.


What are the recovery times of HSR (best case and worst case)?


There is no best or worst case recovery time for HSR, since there is no recovery time at all. The network recovery time from no fault to a single fault in a ring will always be zero. Also, the repair operation from one fault to no fault is also with zero switchover time.


HSR, as MRP or RSTP in ring configuration, can only sustain one fault in the ring network. This is due to the physical topology, not due to the redundancy protocol. Rings that are coupled via Quad Boxes do not share the same redundancy domain. Therefore, each individual ring can sustain a single fault.


Are HSR/PRP standardized technologies or are they proprietary?


Both HSR and PRP are specified in the International Standard IEC 62439-3. HSR and PRP are therefore standardized and not proprietary technologies.


If HSR and PRP are superior to MRP or RSTP, why should I continue to use them? Why shouldn’t I switch over to HSR/PRP completely?


While HSR and PRP are superior to MRP or RSTP in terms of reconfiguration performance, there are also drawbacks to the technology:

  • PRP: Requires a complete network infrastructure for both networks, which usually means double the costs for network equipment.
  • PRP and HSR: For both PRP and HSR, hardware support through FPGAs or ASICs is required, leading to higher device costs.
  • HSR: Compared to an MRP ring or RSTP in ring configuration, HSR carries only 50% of the traffic (available bandwidth is halved due to doubled frame transmission).


Where seamless redundancy is not explicitly needed, the use of MRP (with SubRings) or RSTP technology may be more cost-effective than HSR/PRP. But where the application requirements justify the additional costs, PRP/HSR can be utilized.


If HSR/PRP is a standardized technology, why should I buy an HSR/PRP device from Hirschmann? Other vendors will provide the same redundancy functionality?


There are several answers to this question. It is true that the technology is standardized, but there are several key factors why a customer should buy a Hirschmann HSR/PRP device:

  • Hirschmann was instrumental in the development of the PRP/HSR standard. With Hirschmann products, a customer can be absolutely sure that the device will satisfy every requirement HSR/PRP was designed to accommodate and that, thanks to our detailed insight knowledge, the implementation is of high performance and absolutely 100% standard conformant.
  • A high performance redundancy is almost useless without proper monitoring and fault detection. Hirschmann HSR/PRP switch products will be integrated into our state-of-the-art SCADA tool Industrial HiVision, which adds up to a combined redundancy and network solution that no competitor can match.


What are the typical application fields of PRP and HSR?


HSR and PRP were conceived for use in IEC 61850 substation automation, where network reconfiguration times cannot be tolerated, especially on the process bus with sampled values traffic. However, PRP/HSR can also be used in factory automation, especially as redundancy solutions for motion control applications.


In short, PRP/HSR can be used anywhere when only very low to zero network recovery times can be tolerated. This is especially true in time synchronized networks, e.g. with IEEE 1588v2. HSR in particular with its ring structure and cut-through switching, can also provide very low end-to-end latency on ring networks.


How many HSR ring devices are supported?


The total number of HSR devices in one ring should be limited to 50. This is mainly to reduce the latency in the ring. For very time-critical applications it may be necessary to limit the number of devices even to a smaller number. Another limitation for the number of devices in a ring can be the size of the duplicate detection table inside the device. This is dependent on the implementation.


Are HSR and PRP future-proof technologies? What is the technological outlook?


The IEC standard (IEC 62439-3) for HSR and PRP is now stable and the feasibility of the technology has been shown. HSR and PRP are highly future-proof thanks to the direct integration into the IEC 61850 standard and the acceptance of all major energy automation companies. HSR/PRP technology is expected to be successful in other application fields as well, in particular factory automation. The technology is scalable in line speed (Gigabit speed is scheduled as future improvement to the standard) and can be flexibly adapted to incorporate other technologies, e.g. 1588v2 time synchronization.