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New interlocking readies safety system

Many test trips were made this past weekend to test the interaction between the new train safety system and the existing tunnel technical installations. Should the interface between these two systems be inoperable, this could have major consequences for train traffic. All the more important to thoroughly test its operation before it is activated. System Integration Manager Andre Geuze explains the preparations, the testing itself and the next steps required to make the system operational.

Under contract to ProRail we are building a new interlocking to prepare the safety system for a four-track section instead of the current two-track section.

Test Strategy

The new interlocking we built must be integrated into the existing situation, which means that the system will be interfaced with another system that controls and monitors the tunnel technical installations. ProRail has identified the integration of these systems as one of the top risks of the High-Frequency Rail Transport Programme (PHS) Rijswijk-Rotterdam project. Should this integration fail, this could result in potentially unsafe situations or many malfunctions resulting in train cancellations.

To prevent this at all times, our EMAT plan – which is why we were awarded this contract – includes a test strategy consisting of three test phases. Test Phase 1 was carried out in February. An Integrated Factory Acceptance Test (IFAT) was carried out during this phase: in a laboratory environment, the system was connected to the system that controls and monitors the tunnel technical installations. This enabled us to assess whether the two systems are able to communicate well together. Several minor points for attention were identified as a result of this test, which were immediately resolved and adjusted. Phase 2 – static testing – was scheduled for the week of 17 May 2021 (week 20). In Delft, simulated trains were used to check whether the signals came through and the system responded as required. No issues were identified during this phase. Phase 3 – dynamic testing – was carried out this past weekend. Motion sensors were used to conduct tests with real trains under dynamic conditions (various train speeds). 


To prevent malfunctions at all times, our EMAT plan – which is why we were awarded this contract – includes a test strategy consisting of three test phases

But first the switch

We built a new interlocking alongside the existing interlocking in the same technical areas. An interlocking is a large computer, as it were, located inside the relay house. The interlocking’s software guarantees that the trains can safely drive on the railway. The cable connections that enable to system to control the signals and switches first had to be converted from EBS (the current system) to iVPI (the new system). Converting this ‘switch’ took eight hours to complete as expected. Actual testing could only begin after this.

Train in action 

The test driving itself took seven hours. The train started with a speed of 10 km per hour and worked its way up to 80 km per hour. After this the speed was increased to 100 km per hour and later to 120 km per hour. During these various speeds we monitored whether the information transfer between the systems occurred in accordance with the protocol and whether the systems responded as expected. Specialists from various organisations constantly monitored whether this went well or whether there were any deviations.


Shoulder to shoulder

Strukton Rail’s PMC Signalling & Power Supply worked together with Arcadis. They designed and built the interlocking and facilitated the dynamic testing. The same thing applies to Strukton Rail’s safety department. A special aspect was that the test train was able to drive at the permitted speed on the track section during an out-of-service period. To be able to do this safely, a test track regime was developed in close cooperation with ProRail. The passenger train used to conduct the testing was supplied by NS. ProRail prepared the test programme and managed the testing activities.

Looking ahead

The tests demonstrated that the interface between the systems is working as it should. However, according to plan we did not yet switch over to the new interlocking in this train-free-period (TFP-5b). Suppose we had run into issues during the test, you would then also need time to recover everything. We are providing for just under six months to address all of the issues. The aim is to have a clean sheet for TFP-6. 

Another important point is that we need a permit from the Human Environment and Transport Inspectorate (ILT) to commission the system. It takes a fairly long time to complete this process. We have included six months in the schedule for this, so that we have sufficient time to complete everything. During TFP-6 the virtual switch will be permanently turned off and the new safety system will then go into operation.
The tested interface is unique. Every situation is different and requires custom work. It is not possible to develop a one-size-fits-all method for such an interface.