Communications-based train control (CBTC) is steadily becoming the train control system of choice for both new and existing metro lines.
Currently, most modern RF-based CBTC are being deployed over a Wi-Fi radio bearer. Rodrigo Alvarez, Senior Consultant – Rail Comms at Titan ICT Consultants talks to us about some of the potential issues associated with that design option.
You will be presenting a paper in the IRSE Stream at AusRAIL 2014 on the topic “CBTC over Wi-Fi: Gathering Clouds”. Could you give us an overview of this paper please?
Rodrigo: The paper tries to delve into the reasons why Wi-Fi, that started as an adhoc Wireless LAN technology for research labs and University campuses, has eventually ended up in the core of a safety-critical, mission-critical application like CBTC, and what implications this could have in the future. We will explore some of the limitations inherent to Wi-Fi technology, the reason behind those limitations, the potential impact these limitations could have on CBTC systems and what could be done to overcome those limitations.
It may sound somewhat ambitious, but we believe that this is a discussion that needs to start taking place and a major forum like AusRAIL presents the opportunity to do so.
How do you envisage such process to make a difference to the current CBTC system?
Rodrigo: I think that, being CBTC the undeniable success story it is today, and as RF-based CBTC systems expand into more and more Mass Transit systems in the World, the Industry is already coming to understand how critical the data radio network at the heart of a modern CBTC system is. Everybody in the Mass Transit sector is, little by little, coming to the realisation that you just can’t get away with setting up a “best effort” data radio system, especially as unlicensed spectrum becomes more and more crowded with every passing day.
The Industry is starting to address the problem already, and I am confident that we will reach a point in a few years where these issues will be solved. However, we need to raise the awareness of these realities within the Industry so that change can come by smoothly and quickly. Otherwise, the good name of CBTC as a technology and even Mass Transit as a sector could be jeopardized. Particularly during a period where investment in the sector is facing some politically very strong adverse winds in Australia, all this could have very undesirable effects.
What are some of the challenges that we might encounter when we implement such process? How do we overcome these challenges?
Rodrigo: At heart, as so often is the case, the loopholes in the current use of Wi-Fi for CBTC present less a technical challenge than a human challenge. Convincing the right people that something needs to be done could be harder in many cases than actually implementing those changes. Reputations may be perceived to be at stake, decisions involving millions of dollars may need to be taken… None of this is easy.
However, if we manage to deal with those issues, the fact that Wi-Fi systems present certain weaknesses that are not going to improve with time is undeniable. I think that the intelligent way to approach the problem is to concede that decisions taken a few years ago, based on the knowledge at the time, were reasonable, but that the circumstances are changing and that something needs to be done to adapt to the new conditions before it is too late.
How does your paper reflect the theme of AusRAIL 2014: Making Innovation Work?
Rodrigo: Well… Installing modern CBTC systems certainly falls within Innovation. Looking at ways to make the data radio networks that support those innovative systems more resilient means Making them Work better. Quite a topical subject I believe.
In fact, I think that the way in which CBTC and data radio networks interact is not only a textbook example of innovation at work. Communications (both radio and transmission) are increasingly becoming more and more crucial for modern rail signalling and train control systems. This seems to be a general trend across the railway industry – maybe even across the entire transportation sector – that in many ways is defining the current generation of railway technologies and the professionals that work around them.
This is the equivalent of what lock, block and brake meant to the late 19th century and electrical coloured light line-side signals meant in the 1920s. It is certainly a fascinating moment to be involved in this industry, and I am very excited to be presenting on this very same topic on AusRAIL 2014.
Rodrigo: I was lucky enough to attend AusRAIL 2013 in Sydney last year and I have to say that, even after visiting supposedly bigger rail industry conferences across Europe over the years, I was truly impressed by the amount of effort the Australian rail sector put into its event. I am aware that last year was special, due to the World Congress on Rail Research, but given that AusRAIL 2014 will take place in Perth, which is my adoptive Australian home town, it has a bit of a sentimental value for me.
I am also very interested in seeing what the major players in the sector have been doing during the last year, and I will try to follow some of the papers, to keep abreast of the latest trends and changes in the Industry. And, of course, I will be looking forward to catch up with many colleagues from the East Coast and to give them a warm welcome to the shores of the Indian Ocean, WA-style.
Rodrigo has been involved in railway communications in the UK and Europe for over eight years. His comprehensive experience extends to railway radio telecommunications deployment projects, the integration of advanced railway signalling systems and telecommunications technologies and the design and implementation of railway fixed communications networks.
You can hear more about Rodrigo’s paper on CBTC over Wi-Fi: Gathering Clouds, and ask him any questions directly at AusRAIL 2014 on the 11th and 12th November. Please visit the AusRAIL website for more information.