Abstract. 1 Introduction

Transcription

1 TRACE supervision system for dispatching and passenger information M. Renkema, H. Vas Visser Railverkeerssystemen, Holland Railconsult, Utrecht, The Netherlands Abstract This paper describes the TRACE Process Supervision System (PSS), which will contribute at the fine-tuning stage towards reducing delays, better communication, more efficient use of people and resources, better passenger information and fewer missed connections. TRACE PSS is concerned with the process of monitoring, dispatching and passenger information. An electronic process plan is the most important module of the system. It is connected with an automatic route setting function and passenger information systems. To keep the process plan continuously up to date and free of conflicts, software is already available to detect several kinds of inconsistencies. Decision support software is being developed to solve single problems in an interactive way by offering solutions and related consequences. 1 Introduction In the last few years, Netherlands Railways has invested substantially in extending the infrastructure and developing computer systems to provide better control of the production process. The TRACE system developed by Holland Railconsult and EDS supports this process from the planning stage to operational fine-tuning. The paper deals with the development and nation-wide implementation of TRACE Process Supervision System, which fulfils a need of the Netherlands Railways to handle more traffic on more infrastructure in

2 248 Computers in Railways a fast, flexible and customer-friendly way. TRACE PSS introduces a new working method: many routine tasks will be carried out by TRACE PSS, the process supervisor will increasingly be involved with planning and scheduling. The first release of the Process Supervision System was successfully implemented in the middle of 1994 in Eindhoven. From now until 1998 TRACE PSS will be introduced to all traffic control centres in the Netherlands. Chapter 2 deals with the aims and starting points of TRACE PSS. Chapter 3 describes the main modules of TRACE PSS. In chapter 4 the new working method, implied by TRACE PSS, is presented. Chapter 5, finally, deals with current experiences with TRACE PSS and the consequences of using TRACE PSS related to the working method. 2 Aims and starting points TRACE PSS has been developed from the following starting points: Flexible Task Allocation Allocation to users of TRACE PSS of the sectors and the authority for an area that is being managed by a single process control system must be flexible. Such allocation will enable more users to operate an area during the daytime than at night when there is less traffic. Similarly an area can be divided up between two operators during an emergency. Uniform User Interface TRACE PSS is designed to replace the user interface of all underlying train control systems. The operator is equipped with 1 keyboard, 1 mouse and several screens and can therefore operate all train control systems. Intensive use of ergonomics has been made during the system design to obtain an optimal user interface with keyboard and monitors instead of display panels. Universal Interface with Security TRACE PSS must be capable of communicating with all the train control systems used by Netherlands Railways. All of these systems must therefore communicate with TRACE PSS in the same way. Generic System It was necessary to develop a system which can be used at any location without modifying the software. In other words, any location must be capable of running the same software, the only difference being the configuration. This also means that when the infrastructure changes at a location, only the configuration needs to be changed.

3 Computers in Railways Description of the TRACE PSS system Process Supervisor Conflict detection and decision support TRACE PSS Figure 1 The architecture of TRACE PSS TRACE PSS has been developed in stages in order to minimize the risks associated with its development and introduction. Each stage forms the basis for subsequent developments and provides additional functions such as Electronic Process Plan, Automatic Route Setting, Conflict Detection and Decision Support. 3.1 The basic system The first development stage is the basic system and consists of Flexible Task Allocation, the Uniform User Interface (Manual Control and Display

4 250 Computers in Railways function) and the Universal Interface with Security (Process Interface function). Flexible Task Allocation As the name suggests, this system is responsible for Task Allocation; it determines the tasks process supervisors may perform, the area in question and the operating and monitoring screens they need for such purposes. All persons working at the traffic control centre are known to the system. They are the only people who can use TRACEPSS. When an operator logs into TRACE PSS he must specify the tasks he wishes to carry out. Manual Control and Display This module does four important things: it accepts operating commands from the process supervisor, it shows overviews of the infrastructure to the process supervisor, it passes on messages from the train control systems to the process supervisor and it generates suggestions for action. A consistent set of operating commands has been specified for all underlying train control systems. The process supervisor uses the Operation function to enter operating commands either using the keyboard or the mouse (with pull-down menus and lists). Figure 2 shows the form which can be used for manual route commands. The form supports the user. For instance once the user has entered the "from" track he can call up the possible "to" tracks. After the "from" track and the "to" track have been entered any compulsory choices will be shown. Figure 2 Manual route setting form

5 Computers in Railways 251 The process supervisor sees the state of the infrastructure on monitoring screens which use three types of display, two graphic and one textual. The two forms of graphic display show different levels of detail. One covers the entire area for which the process supervisor is responsible, divided over several screens if necessary. It shows section occupancy, preset routes and disrupted external elements. The second type of graphic display involves an enlargement of the first showing more details such as the colours of signals and the position of points. The textual display gives all the information that is available per infrastructure element. This type of monitoring has to be called up separately. The Assess current situation function presents a list of operating commands which are generated automatically by the system when dangerous situations occur at a location such as a train travelling through a signal which is in the stop position. Process Interface The other TRACE PSS subsystems make use of this module to communicate with the route logic and security systems as can be seen in Figure 1: EBPV comprises route logic, BBS includes security logic as well as route logic. 3.2 Process Plan and Automatic Route Setting The system of the first development stage requires the route process supervisor to set all the routes manually into the system. The next logical step was therefore to add the Route Process Plan, Track Occupation Graph and Automatic Route Setting. Route Process Plan The Route Process Plan contains a database consisting of all the routes which are to be set in the form of arrival and departure tracks, including the time at which movements are to take place. The routes are displayed on a planning screen (see Figure 3). The route process supervisor simply uses the mouse to indicate the correct route at the right time and the route is set. As well as setting routes, the route process supervisor can also modify the route process plan which plays a key role in improving communication between traffic control centres. It ensures that all route process supervisors see the same plan; if two process supervisors are looking at the plan for the same section of track and one of them changes a line in the plan, the other process supervisor sees the modified plan line on screen. Hence there is less need to make phone calls. The link with TRACE traffic control ensures that the route process plan contains up-to-the-minute information such as delays, cancelled trains etc. Track occupancy graph The track occupancy graph should be seen as part of the route process plan which contains plan data for one subsection of the infrastructure. The graph is an planning tool and is designed to show the

6 252 Computers in Railways Figure 3 Route process plan user interface route process supervisor which tracks will be occupied in accordance with the planning, plotted against the time axis. Additional information makes clear which train is occupying which track. Route process supervisors can use the track occupancy graph to determine the tracks which can accommodate a train. They can see the tracks on which a conflict is likely as a result of overlapping occupancy by more than one train. The graph also provides insight into the relationship between different activities such as trains being divided or combined. Automatic Route Setting The next addition to TRACE PSS is, again, obvious. If the system contains a database of all the routes that require setting, why can the system itself not set the correct routes on time? Automatic Route Setting automatically sets all the routes specified in the route process plan. It comes into operation at the precise point in time when the route is to be set and when all the conditions which govern route setting have been met. In the first instance, the route setting time is determined by the time planned in the route process plan. Arriving trains, through trains and shunting trains activate Automatic Route Setting when they cross a previously defined point on the track. Crossing these points will be accepted by Automatic Route Setting only if the difference between the actual time

7 Computers in Railways 253 and the planned time is less than a number of minutes specified by the route process supervisor. Other conditions which apply to route setting are that all ready messages must have been received, the sequence indicated by the process plan is maintained on the destination track (there may not be any changes of sequence to the open track) and the right train is on the starting track. 3.3 Conflict Detection and Decision Support Conflict Detection The aim of Conflict Detection is to support the route process supervisor in planning activities by highlighting inconsistencies and conflicts in the Route Process Plan. The main conflicts are described in this paragraph: Broken connections: guaranteeing passenger connections plays a key role in creating a process plan which is free of conflicts. Route conflict: two planned routes which cross must not be set at the same time. Occupied platform track: a track can not be scheduled for use by two trains simultaneously unless the trains are to be coupled. Route not available: if part of the infrastructure has been taken out of service, there is a possibility that routes can not be set. Broken rolling stock connection: if two trains are being coupled to a third train, the third train may not leave until the first two trains have arrived. Conflict Detection tells the route process supervisor that there is a conflict, but the process supervisor decides how to resolve it. Decision Support helps process supervisors to take the required measures. Decision Support The purpose of Decision Support is to support process supervisors in resolving conflicts which the Conflict Detection system has noticed during disruptions. Support takes the form of a number of sets of measures which modify the process plan in such a way that the passenger product continues to meet the specifications as effectively as possible. Decision Support uses a cost function to calculate a number of measures and establishes the set of measures to produce an optimized plan. These measures and less optimal solutions are presented to the route process supervisor who ultimately decides whether to accept the recommendations of the Decision Support system.

8 254 Computers in Railways The cost function calculations are based on a number of criteria, the most important of which are as follows: Delays: a delay is calculated by comparing the predicted time of departure with the original planned time of departure. Changes of track: a distinction is made between platform track changes and unoccupied track changes. Platform track changes can be extremely annoying for passengers, especially if cross-platform connections are broken. Changes of sequence on open track: changes of sequence on open track create major deviations in the pattern of the passenger service, which can result in mistakes by the process supervisor and other members of staff. Decision Support will have to take this into account. Breaking passenger connections: generally speaking, breaking passenger connections will result in additional conflicts at a later stage Breaking rolling stock connections: generally speaking, breaking rolling stock connections will result in additional conflicts at a later stage. 4 New working method The new method is designed to make the process plan as consistent as possible so that Automatic Route Setting can take over an important part of the job of the route process supervisor, i.e. setting routes. The Route Process Plan is the electronic version of the rail timetable containing all the train movements which are to be carried out at one location. It occupies a central position in TRACE PSS. The Automatic Route Setting module uses the plan to set routes. It cannot do so unless the process plan constitutes a consistent and practicable whole. The route process supervisor has a number of resources at his disposal to ensure that the process plan is practicable and consistent. First the plan is presented in the form of a Track Occupancy Graph which gives a useful overview of planned track occupancy and enables the process plan to be modified simply without any track occupancy conflicts. Conflict Detection and Decision Support are more sophisticated tools. Conflict Detection identifies conflicts and inconsistencies in the process plan and presents them to the route process supervisor. The Decision Support module presents a number of solutions for each conflict situation arranged according to the quality of the measures. The route process supervisor performs a simple action to implement proposed modifications to the process plan. All of these tools are designed to produce consistency in the process plan so that Automatic Route Setting will set routes when there is a train with the right train number, when the route setting time has been reached

9 Computers in Railways 255 Figure 4 A TRACE PSS Control desk

10 256 Computers in Railways and when there are no obstacles in the infrastructure. The task of the route process supervisor will increasingly involve planning instead of directly determining the point in time when a route should be set. Since routine tasks are carried out by the system, it becomes a challenge to think up clever solutions to eliminate problems in the process plan. 5 Conclusions TRACE PSS will be introduced to all traffic control centres in the Netherlands from now until We have already mentioned that working methods will change. So too will the technical infrastructure. Display panels will disappear and be replaced by computer screens. The new system will be introduced at each centre in stages starting with the basic system. More advanced tools like Automatic Route Setting, Conflict Detection and Decision Support will be introduced during the next phase. The functionality of two control centres has already been extended to include Automatic Route Setting. Conflict Detection and Decision Support will follow towards the end of As the introduction of TRACE PSS will bring about changing working methods and flexible task allocation, a number of smaller traffic control centres will be closed down. Initial experience with this comprehensive supervision system is highly encouraging. It definitely increases efficiency, enabling a larger area to be handled by the same number of route process supervisors. However, the new working methods involve quite different tasks and have consequences for process supervisors who will therefore require considerable guidance.