MODERNIZATIN TRENDS FOR THE TRAFFIC SAFETY DEVICES

Starting with the '80s on a wordily level, there has been accentuated the tendency of using a new generation of railway centralizing devices - the electronic centralizing device based on calculus technique.
From the point of view of the realization of such a device there are two concepts unanimously accepted: the principle of the majority logic as well as the diversity principle. The two approaching ways are probabilistic principles of realization of the safety while functioning, fact that makes them so different to the fail-safe classical principle (with inner safety) used for the anterior railway centralizing types.
The majority logic principle is based on "2 from 3" and "2 from 2" variants, using three or two processors that rule the same program. As a safety principle, we use the reciprocal testing of the results obtained from the two processors on different levels of the functioning process. If the answer of at least two processors is identical, then the imputed command is valid. On the "2 from 2" system (cheaper) the invalidity of one of the operations leads to failure of the device.
On the "2 from 3" system, because of the redundant characteristics, no failure is possible. Should a processor become invalid, the decisions are made between the second and the third processors. At the main control panel it is used the "2 from 3" logic and for the monitoring the terrain objects (lighten signals, switches, isolated sections, etc) it is used the "2 from 2" logic (in this case any failure will affect only the failed object, on one hand; on the other hand the possibility of any failure occurrence for any object is much more reduced than the failure of the calculus systems).
The diversity principle uses only one processor that sequentially performs two different programs, programmed by two different programmer teams, with different programming techniques. The main software of the application uses a cyclic working system, with pretty long periods of data transmission and verifying cycles. Mainly, the application software is based on turning all Boolean equations of the classical schematic relays into programs. Most recently used techniques uses software modules for the known program sequences. From the point of view of the hardware, the processor must have a big functional response quality.
As a model of the centralizing installation displaying in the field, we distinguish two kinds of systems: central logic systems and distributed logic systems. Any known solution of electronic centralizing installation is available in the two variants.
The distributed logic system has its zone counters and interfaces spread in the field (special buildings, containers or drawers), but the logic of the transmission network is centered from the main control panel. The link between the main control panel and the field unites is redundantly performed through classical cable or fiber optics (often by passed).
The system is conceived to reduce the length of the cooper cables, to improve the energy consume and to increase the interfaces' performances. Taking into account the permanent danger represented by the burglary and vandalism attempts on our railways, it has been agreed that we have to choose in favor of the central logic system.
The most important firms in Europe that developed electronic centralizing systems are(in alphabetical order): ADTRANZ (Swede, the EBILOCK system), ALCATEL (Germany, the L90 ESTW system), ALSTOM ( France, the ASCV and SSI systems), DIMETRONIC (Spain, the SSI and WESTRACE systems), SIEMENS (Germany, the SIMIS C and SIMIS W systems), WESTINGHOUSE (England, the SSI and WESTRACE systems), GEC (England, the Ssi system).
We can add here also the electronic centralizing American systems: VIP, created by GRS enterprise (part of the ALSTOM company), MICROLOCK II of the UNION SWITCH enterprise (part of the ANSALDO company) and ELECTRO LOGIC of the HARMON Industries.

The latest Romanian achievements
At the Ploiesti Sud rail station a SIMIS W electronic centralizing device with VICOS OC 111 graphic interface is about to be finalized, produced by SIEMENS AG enterprise. The first decade of the mount of April 2001 has been decided to be the official launching date. The contract stated that the supplier had to provide us a SIMIS C device, but as the project advanced, they have decided to supply us the SIMIS W modern variant within the same amount of money.
The initial contact also stipulated the fact that the device for Ploiesti Sud rail station should have included the functionality characteristics and the operational rules of the DB AG German railway, with only two modifications. This proved in the end to be a mistake because of the big differences between the safety and operational concepts of the two railways. These differences couldn't have been compensated by special using specifications. Starting with April 1996, a tem of Romanian specialists worked together with the SIMENS AG enterprise to work out all the differences, so that now all these divergences have been clarified and the specific software created by the SIEMENS for Romania is now in tests.
Along with the electronic centralising device at Ploiesti Sud a new signalling code with multiple speed stages will be introduced for the Romanian Railways, in perfect concordance with the UIC 732 R stipulations. The new signalling code introduces signals separated (by luminous figures- registered on fibre optics posts), both for the speed on signal (if this one is less than the established speed) as well as for the forecasted speed for the next signal. The new code introduces the four-indication distancing speed, replacing the three-indication speed presently used.
The system is perfectly compatible with the present one, without any confusion. Actually, the minimal modifications are very easy to learn and to be applied by the Romanian railway men. The new signaling code represents the developing of the existent system, or in other words the two-speed stage system's improvement. By adopting this signaling code we will no longer use the four-speed signaling system that has been used for almost four decades in special cases when we confront with deviation increased speed.
The four-speed stage distancing signals will be the support any maximum increasing speed up to 160 km/h on the IV Corridor without changing the length of the rail block sectors; this will sure be an advantage in combined traffic situations.

European projects
On international level, there is an initiative of the UIC -the EURO-INTERLOCKING European project- already involving 16 countries among which Romania through CNC CFR-SA, as well as a great number of centralising equipment producers (as there are observers from our country- ISAF SA, Electromagnetica SA Bucharest and SMD Bucharest).
The EURO-INTERLOCKING project has as aim to realise a unified centralising system based on commune technical specifications. The hardware platform remains at the producers' choice. This will permit to all producers to substantially reduce the projecting manufacturing costs of the installations. Thus, according to the specifications of the EURO-INTERLOCKING, any installation device will be implemented within a short period of time with low costs for each of the participant countries. We expect a significant cost and implementing time reduction.
A recently finalised project of the European Union concerning the technical specifications represents the ERTMS/ETCS project (European Train Control System) realised to insure a better inter-operative system on the European railways.
Romanian Railways intend to introduce the ETCS level I on the IV pane-European Corridor- Curtici-Brasov-Bucuresti-Constanta, rehabilitating and modernising the 160 km/h speed traffic; the classic INDUSI system for the areas where the maximum admitted speed is 120 km/h will be also maintained. A first step for the implementation of the ETCS level I will be the Arad-Bekescsaba (Hungary) trans- frontier project involving the Romanian, Hungarian and Austrian Railways that will work together to promote it.
Another European project concerning technical specifications actively involving Romanian Railways is represented by the LC-TCS (Low Cost-Train Control System). This project is likely to be a lower- cost variant of the ETCS system used on the secondary rail-tracks.
On the UE's level they intend to integrate of all these projects: ERTMS/ETCS, EIRENE (communications), LC-TCS, EUROBALISE, EURO-INTERLOCKING within a unitary system enabling the inter- efficiency of different international railways.
With the support of the European Commission consisting of PHARE founds, we organise the ROMANIA PHARE Ro 9604-01-02 auction for electronic centralising devices in four big railway stations: Brasov, Arad, Timisoara and Bucurestii Noi. Technical specifications for the offered systems have been conceived including all the difficulties the Hungarian, Russian, Bulgarian and Italian railways confronted in the past. At the beginning of the electronic centralising devices' implementation even Holland, Belgium, Switzerland and Finland had problems. That is why the most important system's demands are:

The European organisms made important efforts to normalise certain railway concepts as CEN, CENELEC, ERRI, UIC, so that there should be a common interest in the developing and harmonising the technical and safety conditions for different railway administrations.
Within the common strategy of developing the safety traffic installation at the Romanian
Railways, certain aspects are to be fulfilled: electronic centralising of the most important rail stations, computerisation of the rail agent's control panel post, replacing the electro-mechanic and mechanic installations with simple electronic centralising devices or with simplified CED installations, introducing axe counters for controlling the off state of the rail between two rail-stations with no rail block, modernising the rail tracks, etc.
On the route Sibot-Cugir without any automate rail block there will be introduced axe counters; this is a project offered by the ALCATEL enterprise, Germany. The Sibot and Cugir rail-stations are electric-dynamic centralised, but the distance between the stations is not at all under control. There will be introduced two axe counters, one in Cugir and the other one in Sibot. The link between the two will be made on the existent cooper cable. It is possible to use fibre optics, too. The axe counters are of the sense discrimination type. When one train leaves the station with current rail, the respective counter lists the number of the exited axes and communicates it to the counter from the neighbour station. The rail is declared "occupied". If the train enters the next station with all the axes (meaning that the number of axes is the same), the line is declared "free" and both the axe counters are put on reset mode. In case the two lists received from the both axe counters are not the same, the line is also declared "occupied".
Using the simplified CED systems, together with the axe counters will create the premises for lowering the costs in replacing the mechanical installation devices on the secondary rail-tracks.
Computerising the control panel of the rail agents represents in fact, computerising the classic centralising installation device with relays. There are many advantages as:

Dumitru Munteanu

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