Provisioning of Safe Train Control in Nordic Countries

The safety of train traffic is a vital societal function. During the mid-1970s, the availability of inexpensive microprocessors and electronic components led to the first computer-based systems solution to this critical function. Sweden was the first country in the world to develop and deploy a computer-based solution for Automatic Train Control (ATC). The major suppliers Ericsson Signal Systems and ITT Standard Radio developed solutions for both of the functions required; namely the track to train transmission system as well as the onboard system. Both system functions have been further developed by companies that have taken over ownership of these system products; namely, Bombardier, respectively Ansaldo. In the original delivery to the Swedish Railways (SJ), Ericsson Signal delivered the track-to-train transmission system; whereas, Standard Radio the onboard system for SJ trains and Ericsson Signal delivered the onboard system for the Stockholm Local Traffic (SL) trains. We describe the functions provided by both systems; however, we place focus upon the unique properties of the Standard Radio onboard system that has had a stable architecture for over twenty-eight years. The two track-to-train transmission systems delivered by Bombardier and Ansaldo are compatible; in Norway, both suppliers have delivered their products for both of the functions. Further, the X2000 and Öresund bridge trains that travel between Sweden and Denmark utilize the Ansaldo onboard and track to train transmission products in combination with a Siemens system. In addition to the details of the Swedish ATC solution, a brief historical perspective of train control as well as the implementation of train control in the other Nordic countries is provided. The need for a holistic view of train control is cited in examining two actual train accidents in Sweden and Norway. Finally, we discuss the movements toward a European Rail Traffic Management System standard in respect to interoperability of train