The Limits of Standardization: Why Local Public Transport Needs Its Own Control and Passenger System
30 Sep 2020 - Technology, Transport
Whether regarding the questions of pollution levels or urban congestion: Regional and local transport will continue to grow in importance in the coming years. To meet these needs, the supply must grow accordingly. The expansion of infrastructure is only one option – especially since it requires a long-term horizon for planning, approval, and construction. By contrast, one popular idea is increasing the schedule frequency by shortening the time between trains.
But what about the required technology? Can systems like those already in service in the newly constructed networks in Asia or South America be used? Or will control systems like those developed for long-distance transport be used here?
Operators, cities, and municipalities are desperately seeking efficient solutions to quickly and reliably serve continuously growing passenger numbers. Since the construction of new infrastructure is time-consuming and costly, the preferred solution in an urban context is to increase the frequency of trips.
But here, too, there are limiting factors, which include
- vehicle procurement,
- recruiting and training additional drivers and
- increasing the frequency of trips which quickly pushes existing technology to its limits.
For this reason, automated driving – including the (partial) automation of complex control processes – is attracting increasing attention from public transport system operators.
Demands, primarily from the area of standardisation, are pushing for the adoption of proven solutions from the long-distance transport sector. However, assumptions that the transfer of control systems from one area to another would be easy have proven false. One important factor is that in most cases, the infrastructure is not completely new; local and regional transport systems have significant differences from long-distance transport that must be reflected in the control systems.
Short Routes and Journey Times
The main difference to long-distance transport is the shorter distance between stations and the resulting significantly shorter travel times.
This causes many differences and additional challenges for the control systems. For example, travel times and the length of stops at stations, i.e. the time for passenger changes, are often the same. Long-distance systems rarely consider junctions with increased passenger volumes. As a result – unlike with long-distance transport – even small irregularities very quickly lead to operation no longer being on-time due to the lack of buffers to absorb delays.
For control systems to function reliably even on the shorter routes and when trains are running at high frequencies, precise and frequent vehicle tracking is required. Satellite positioning has improved considerably in recent years thanks to the various systems GPS, GNSS and Galileo, but it cannot be used in tunnels or in the covered viaducts of the underground railways.
The use of balises in the track or RFID tags (RFID: radio-frequency identification) on the platforms is viewed as a promising solution. Vehicle tracking systems like this can also be used to implement partially or fully automated operation based on GoA0 to GoA4 operations.
What is a balise?
A balise is an information carrier mounted in the track – a magnetically coupled transponder. It transmits data to the vehicle when the train passes over it, enabling information to be transferred from the track to the vehicle at specific points.
Missing Alternatives in Case of Disruptions
Of special importance in local transport is the fact that, as a rule, there are no alternative routes in case of disruptions. This is another major difference to long-distance transport that must be considered in control systems for dispatching. Combined with the high frequency of operations, a correspondingly faster reaction in the event of disruptions is required. This applies equally to decision-making and passenger information. Specialised control systems can provide valuable services, e.g. by shortening decision-making times with the help of templates for typical disruptions.
To be able to react quickly, operators must be able to set priorities quickly. The systems must swiftly provide the required overview, and operation should require just a few clicks. An important part of this is ensuring that relevant dialogues for these decision-making processes remain current by utilising live data and that possible subsequent conflicts are immediately visible in a preview in dispatching to prevent subsequent conflict.
Finally, great potential remains to be discovered by applying AI technologies. With their help, decisions and their effectiveness can be recorded over a longer period and then evaluated to improve processes.
Infrastructure and Train Operation From a Single Source
One great advantage is the still common special ownership situation in local transport. In contrast to long-distance transport, it is taken for granted that metros and trams are owned and operated by a single entity. Often, this advantage is already no longer present in the local transport of regional railways operated by the main railways.
The close integration of infrastructure and operation creates significantly simplified organisational structures in networking and equipping tracks, stations, tunnels, etc.
This makes it easier to design an end-to-end IT system – from data collection and vehicle tracking, to vehicle control, to operational procedures and passenger information. Since operations and infrastructure are unified, dispatching systems can often even directly access the signal box data. This, in turn, simplifies train tracking and enables routes to be switched without delay – using secure and certified interfaces. Here, functional and operational safety remains within the signal box.
Reliable Passenger Information Systems for Commuters and Tourists
Finally, the unique features of urban public transport must also be reflected in the functions of passenger information systems.
Crucial for both local and long-distance transport: the foundation for a high-quality information system is the consistent tracking and control of vehicles.
In long-distance transport, the main concern is the correct display of the position on the platform, for example the location of the car with the booked reservation, or where the dining car is located. A modern passenger information system for local public transport however includes much more than just displaying the next train’s arrival on a display. Required is
- providing reliable information about the actual next journey and its terminal station,
- the accurate display down to the occupancy level of each compartment or car, for example to identify barrier-free boarding positions as well as
- the consistency of information across all display and announcement media, apps and social media channels of public transport companies.
The Rhätische Bahn Shows How It's Done
The Rhätische Bahn (RhB), for example, has demonstrated what such a dispatching system with integrated passenger information system can achieve in regional transport. Its network comprises around 100 commercial stations and stops. Along its routes, the Swiss transport company transports not only commuters, but also international tourists. It must fulfill the varying demands of its diverse passengers.
To achieve this, the RhB relies on a multilingual dispatching and passenger information system from PSI. The system has a modular design which reflects the importance and size of each station. Of special significance is the current introduction of shuttle vehicles and coupled trains, which make it possible to implement new operational models.
The coupling of vehicles in traction units is increasingly common in regional transport. Doing without purely locomotive-hauled trains makes it possible to provide good service even in less frequented areas – with just a few additional drivers. This new form of operation also poses special challenges for dispatching and passenger information:
- The most important task is assigning the partial trains to their respective destinations and
- another challenge is handling the individual partial train components in case of delays.
Specifically, that means dispatchers must have clear and prompt information to make correct decisions and provide passengers with precise information.
TFT overhead displays (TFT: thin-film-transistor) are used to provide information on the coupled train formations. The current train formation is imported through an interface to the car management system and displayed to passengers (1st class, 2nd class, dining cars, etc.). Sector information is determined according to the actual train composition and displayed (which part of the train with which destination stops in which sector). Here, the passenger information system reacts completely automatically to scheduling changes (e.g. change of sequence at the coupling station or different train length) and provides the driver with the necessary information about the new stop point in the station.
Own Systems for Local Public Transport
The desire to adopt existing, proven standard control systems is more than understandable. However, a look at practical experience reveals significant differences between local and long-distance transport – especially when considering that it is rare to be dealing with completely new infrastructure. Local transport therefore requires its own standard systems, specially adapted to meet its specific challenges. From a technical point of view, there are no hurdles to this approach.
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