Fabio Senesi, Giorgio Bonafè, Stefano Geraci, Massimo Frandi, Nazzareno Filippini and Raffaele Malangone. ATC project team, Rete Ferroviaria Italiana
This month sees the long-awaited start of commercial services on the Milano - Bologna high speed line, with effect from the European timetable change on December 13.
Pre-launch testing of the 200 km route began on October 1, using three ETR500 trainsets equipped with diagnostic systems to work a shadow service of 20 trips a day. Later stepped up to 60 trains/day, this was intended to ensure that all of the infrastructure, including the ETCS Level 2 train control and GSM-R communications network, was fully functional ahead of the launch.
Rapid development of the Italian high speed network in recent years, and increased the need for monitoring of infrastructure and rolling stock performance efficiently, reliably and ideally at low cost. RFI has therefore purchased two ETR500 trainsets. These have been equipped to measure the dynamic performance of the vehicles and pantograph to identify infrastructure conditions, rather than relying on direct measurement of the track and wire geometry. Post-processing of track and overhead line data after each testing run supports a predictive diagnostics process.
Diagnostic train ETR Y1 has been used for the commissioning runs on the Milano - Bologna line at speeds of up to 355 km/h, whilst checking the complete set of infrastructure parameters. This is a new Italian speed record, exceeding the 352 km/h achieved on the Torino - Novara line in 2006.
When the Bologna - Firenze route opens in December 2009, Italy will have 500 km of Alta Velocità line equipped with Level 2. Work to install ETCS is still in progress elsewhere, and further lines will be commissioned over the next few years, using both Level 2 and Level 1.
ETCS Level 2 is already in service on the Roma - Napoli and Torino - Novara high speed lines which marked a step change in Italian train control technology. The experience which we gained on the first two routes has allowed functional and technical improvements to the installation and commissioning process, as RFI and our suppliers have gained a better understanding of what is needed.
Following experience with Roma - Napoli, a mixed RAMS forum was established, bringing together RFI, Italferr and the various suppliers to analyse and evaluate all the technical problems which arose during the installation of ETCS on the Torino - Novara line. This has proved so successful over the past two years that RFI and Italferr have replicated the approach for the Milano - Bologna project.
Many of the problems which we encountered during the commissioning of the first ETCS installation on the Roma - Napoli line were solved by the time we came to commission Milano - Bologna. While we have of course made some technical improvements, the main focus has been on solving or avoiding the practical problems encountered the first time around. This has seen the adaptation of many elements in the application of ERTMS.
Moving to SRS 2.3.0D
The Level 2 equipment on both the Roma - Napoli and Torino - Novara routes uses System Requirements Specification 2.2.2 which was current when these lines were inaugurated in 2005-06. However, ERTMS specifications have moved on substantially in the past two years.
The fixed equipment and the radio block centres on the Milano - Bologna line are fully compliant with SRS 2.3.0D, which was adopted earlier this year as the common European standard. However, the on-board sub-systems are still using SRS 2.2.2, although tests have shown that the trains are compatible with the trackside equipment. A software upgrade of the on-board systems to SRS 2.3.0D is planned by 2010.
Unlike Roma - Napoli, the Milano - Bologna and Bologna - Firenze high speed lines will have computer-based interlockings distributed between many different stations, although the vital control of the entire line will be concentrated at a single site. This fully-integrated system allows the signalling at several stations to be supervised from a single location, with the same reliability and mean time between failures as a conventional computer-based interlocking.
The hardware and software for the radio block centres have been re-engineered to give improved performance. In comparison to the equipment on the Torino - Novara line, the second-generation RBC provides a more efficient distribution of the hardware elements between the equipment racks. Only four racks are needed to accommodate three RBC2G modules, compared to eight racks for two RBCs of the earlier design. Some components have also been changed, reflecting the evolution of solid-state electronics and the need to ensure the availability of replacement parts in future years.
The software has been altered to reduce its complexity, but not the functionality. Reducing the time window allocated for each single train path to less than 1 min will also enable us to manage a greater number of trains on a given section of line. The Level 2 functionality has also been extended, and now includes a drive-on-sight mode as well as integration between the signalling and the hot axlebox detection system.
Like the earlier lines, the signalling and telecommunications data for the Milano - Bologna line are carried by two physically-separate optic fibre networks. But whereas the earlier installations had an independent optic fibre link for networks carrying both signalling and communications for each track, the new arrangement sees one cable dedicated to signalling and the other to communications.
This architecture is specifically designed to support a number of ‘light’ interlockings dispersed along the route.
To assist the development and testing process, RFI has established a laboratory in Roma. This contains examples of all the different ERTMS sub-systems from various suppliers which are in service on the Italian high speed network. By allowing RFI to undertake convenient and rapid testing of fixed and onboard sub-systems, this has enabled us to test the compatibility and interoperability of all possible permutations of lineside and onboard equipment.
As the development, testing and certification of new equipment is continuing, RFI is setting up additional testing facilities to look at a range of factors. These include the assessment of specific applications; functional development and type approval; integration of sub-systems from different suppliers; checking equipment before installation; non-regression testing of software releases; and training and simulation work for the harmonisation of operational rules.
A ‘multi-technology laboratory’ has been established to undertake integration tests using devices provided by a wide range of suppliers and perform non-regression tests in the event that a software or hardware update becomes necessary on lines which are already in commercial operation. This extensive use of laboratory testing has already saved a lot of time and reduced commissioning costs substantially.
A major part of the work has been devoted to the integration of the testing undertaken in the GSM-R, ETCS and interlocking laboratories. The experience we have gained through automating some of the tests is also now being applied to more generic applications.
During 2009 RFI and our Spanish counterpart ADIF will be co-operating in a joint European Vital Computer test programme funded from the Trans-European Networks budget. Each infrastructure manager will select a company to deliver an SRS 2.3.0D-compliant European Vital Computer, perform the certification processes using the whole set of sequences specified in Subset 076, and then switch between the Italian RFO and Spanish Cedex testing methods (Fig 1).
Formal language research
Meanwhile, RFI is working with Italian universities to develop GSM-R security and a formal specification for interoperability between ETCS Level 2 and legacy Italian systems.
This month we expect to announce the results of work being undertaken to develop a diagnostic network for GSM-R signal integrity detection. This is being done in partnership with Intecs and Pisa University and funded by the European Commission.
Experience in Italy and elsewhere in Europe has highlighted the problem of ambiguous wording in some ETCS specifications which creates a risk that suppliers might interpret them differently. RFI’s ATC group is working with Salerno University to try and eliminate this possibility by implementing a logical process for specifying the handover interface between Level 2 and Level STM using the Statemate Magnum tool, following the validation process used to test ETCS specifications.
This work has proved a good example of the advantages of formal specification, both in terms of ensuring the logical consistency and permitting simpler validation. Our method represents a new approach to validation, reversing the conventional way of developing and validating formal specifications.