France Figure 1


Train securing functions


Train spacing- moving block


Control centre Interlocking


Wayside train control


Figure 2


Location request


End of authority


Automatic Train 1


Speed control curve


End of authority


Automatic Train 2


and telecoms Network Object controllers


identify all the track resources that it will need to perform its next movement. The train then asks the corresponding object controllers for these resources. Each object controller responds to the train to confirm that the requested resources have been allocated and are locked, and if needed moves the points to the requested position. When resources have been booked and locked, the train can extend its movement authority and move. When the train has passed a track resource according to its own automatic train protection (ATP) primary detection, it immediately releases the resource which is then available for another train. As soon as a track resource is booked, and as long as it is not released, it cannot be used by another train, and all safety principles are enforced.


This new method of working makes train movement very flexible because the train can safely travel from its


Onboard train control


Figure 1: new Urbalis train centric architecture elimiates interlockings and wayside train control. Figure 2: continuous direct communication between consecutive trains ensures the correct headway is maintained along with the speed control curve.


current position to any other location as there are no longer any traditional constraints from interlocking principles and the track becomes a commonplace. Other train movements are possible such as bi-directional or shuttle operation, and turn-back at an intermediate station or the end of the line. According to customer needs and practices, all operational principles can be implemented through an overlay of this core mechanism.


In conventional CBTC systems, trains


regularly send their location report to a zone controller. After processing the reports, the zone controller sends back an end of authority to each train which enables the train to define its speed control curve. This implies periodic communication between onboard ATC and wayside ATC (zone controllers). The moving block principle is


retained with Urbalis Fluence, but there is direct communication between two


consecutive trains to ensure the correct headway is maintained (Figure 2). The following train asks the preceding train for its position, and the preceding train sends back its current position, updating it regularly. This allows the following train to immediately update its speed control curve. As there are fewer subsystems and interfaces, response times should be better leading to improved performance. Alstom estimates that Urbalis Fluence will result in a 20% reduction in lineside equipment and will be about 20% quicker to install because less engineering and configuration is required. Maintenance will also be simplified as the equipment will be installed on the trains rather than out on the track and so it can be attended to in the depot. As Urbalis Fluence is expected to be cheaper and simpler to implement and maintain than conventional CBTC, it should be a viable option for installation on monorails and automated light transit systems thereby expanding the market for CBTC.


Computer rendering of the interior of the trains Alstom is supplying for Lille. 30


Another important benefit is that there are no more inter- sector constraints. Line extensions can be equipped more easily, without impacting the vital data-preparation of existing sections. Nevertheless, Alsom still sees a role for its conventional Urbalis 400 CBTC systems. “We will offer both systems because there will be some customers who want to retain their interlockings or who have mixed traffic operation, and particularly where a customer wants to extend an existing line,” says Mr Pascal Clere, Alstom’s senior vice- president for transport information solutions. “We will therefore continue to develop Urbalis 400.” IRJ


IRJ June 2013


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