How mipro’s interlocking and ats-system run the safest metro in the world?

Almost 100 million journeys are made in the Helsinki metro every year. On average, 270 000 passengers rely on the punctuality and safety of the metro every day.

The metro from the centre of Helsinki to Itäkeskus was originally opened during 1982-83. Over the years, new stations were opened on the metro line, as well as the eastern extensions to Mellunmäki and Vuosaari. However, the biggest change to the metro line was in 2008, when the City of Espoo decided to expand the metro line to Espoo. Construction of the West Metro (Fin Länsimetro) section from Ruoholahti to Matinkylä began in 2009.

Mipro was selected to deliver the interlocking system, ATS (Automatic Train Supervision) -system and the passenger information system for the new RuoholahtiMatinkylä section in 2015. Passenger traffic on the RuoholahtiMatinkylä section began in autumn 2017.

As a follow-up to the West Metro project, Mipro also renewed the interlocking system and delivered an ATSsystem and a passenger information system to the existing Helsinki main metro line east of Ruoholahti. Mipro’s systems replaced the previously used system on the line. The update on the interlocking system was implemented during 2016-2019. The interlocking system and ATS-system were commissioned during a one-weekend traffic break on 11-13 January 2019.

After the first phase of the West Metro and the update of the main metro line, construction began on the second phase of the West Metro on the Matinkylä Kivenlahti track section. The construction of this section has progressed to the system testing phase.

Photo: West Metro test run in Finnoo

During the construction of the metro, the systems go through several different testing phases. Comprehensive testing ensures the safety and smoothness of passenger traffic before commissioning. For Mipro, the site integrations tests (SIT) of the West Metro’s Matinkylä-Kivenlahti extension have been completed for all stations and for the new underground metro depot, and the work has proceeded to the test runs covering the entire scale. The goal of collaborative testing was to ensure that the system is compliant, functional, safe and suitable for the operating environment. Collaborative testing is a requirement for the now ongoing test runs.

What does the interlocking system control in the metro and what is being tested during the site integrations tests?

In its simplicity, the interlocking system secures the train’s passage. In the metro, this safety is based on routes that are set for the train, which means reserving a short section of track for the use of a single train. The route is protected from other trains by light signals, flank protection points and magnetic trip stop system. Before a route can be set for a train, the interlocking system ensures that the route conditions are fulfilled.

Photo: Mipro’s interlocking

Among other things, the interlocking system ensures that there are no other trains on the route and that the track-side equipment, that ensure the safety of the track, are working like they should and fill the requirements for the route to be set. Once the train has received the signal to run on the route, it can proceed on it. The interlocking system detects the progress of the train on the route. Once the train has passed the route reserved for it, the route is cleared automatically and a new route can be set again for the next train.

The biggest part of the site integration testing is to test all the systems and devices installed on the track and along the track that secure the train, and those devices’ interaction with the interlocking system. Such devices include signals, points, track circuits and the train emergency stop system. Each device has its own function in terms of functionality and safety of the system. In site integration tests, the operation of all track-side equipment is tested individually, up to the user interface of the ATS -system, after which the correct functionality, safety and availability of the systems are ensured.

The interlocking system of the West Metro consists of several interlocking devices located in the equipment rooms of different metro stations. In order to work seamlessly, these devices need to communicate with each other. Therefore, in the testing phase, the data communication connections are also tested. Functional communication connections are also required between the interlocking system, the ATS -system and the passenger information system at passenger platforms.

Mipro’s ATS -system controls the operations of the interlocking and passenger information systems

So, the interlocking device protects the passage of metro by setting paths for the trains. How does the interlocking system then know where the train wants to go and where the path should be set?

Under normal circumstances, metro traffic is based on schedules. After the completion of the Helsinki metro, the first phase of the West Metro and the new MatinkyläKivenlahti section, the interlocking system of the entire metro line will be controlled by Mipro’s ATS, or Automatic Train Supervision, system. By importing schedules into the ATS system, it automatically requests the correct routes for the trains from the interlocking system in a timely manner. Upon receiving the request, the interlocking system ensures that the route is safe to set and either rejects the route request or sets the route.

The ATS system is a tool for traffic controllers that allows them to monitor the flow of traffic, set routes even without automation and handle possible exceptional situations. So, the system’s automation functions control the setting of the routes and act as a tool for the traffic controller. In addition, the ATS controls the passenger information displays on the platform of metro stations. The operation of the ATS system and its seamless interoperability with the interlocking system and the passenger information system is an important part of the smooth running of the metro. Because of that, comprehensive testing of the ATS system is an important part of the ongoing test runs.

All in all, the testing and test run are important and lengthy work steps for which there is no shortcut. Despite point testing and functionality testing of individual devices, only the interoperability of all systems during normal traffic and in different exceptional situations indicates the readiness of the system to start operating. In these testing phases, co-operation between different parties is particularly important; after all, everyone’s goal is to build the safest metro in the world, in Finland.

The MatinkyläKivenlahti section of the West Metro is expected to start operating in 2023.

Read more:

ATS Automatic Train Supervision

Metro interlocking system

Videos about the metro project:

West Metro extension test run phase

Mipro’s West Metro signalling system project

Metro interlocking system commissioning 2019


Janne Siirilä

Account Manager

Janne has almost 20 years of experience in interlocking and rail traffic control systems, of which about 15 years are in metro traffic.

At Mipro, Janne works as an Account Manager, responsible for customer services in urban traffic.