The ATC system (Automatic Train Control) to be built for Helsinki consists of a number of different systems, which together will result in a fully functioning automatic metro.
Signal boxes and control system (ATS)
The task of the signal boxes is to safeguard the means of passage of the trains, or in other words, to reserve for each train its own section of track and ensure that no other trains are guided onto the same section. Accordingly, the signal box controls the track devices, such as signals and switches.
The utilization control means a computer system, through which the signal boxes usually run. In normal circumstances, it also automatically performs a number of additional routine tasks.
In the context of the automatic metro project, the present relay signal boxes will be replaced with new, electronic, signal boxes. Functionally, they will be able to safeguard the current metro traffic in the form of relay signal boxes during the transitional phase, and later in possible exceptional circumstances. During normal automatic operations, the signal boxes control the track devices (switches etc), but the supervision in regards to the distance between the trains will be handled by other systems.
Along with the signal boxes, the utilization control system (ATS, Automatic Train Super-vision) will also be renewed. The new ATS will be a system that supervises and manages the operations of the whole automatic metro, whilst at the same time being the most important channel for the control room staff to manage the different parts of the system.
Continuous access control system (ATP)
At present, the Helsinki Metro has point-to-point access control. It interrupts the passage of the train, if the train passes a red signal or travels too fast through a speed monitoring point. In the traffic, appropriate safety margins are however used, whereupon the danger of collisions does not arise, even if the train passes a red signal. The required emergency breaking distance is included in the passage reserved for the train.
The point-to-point access control is however not applicable to traffic that is denser than at present, due to the required safety margins. Therefore, in the context of the automation project, a continuous access control system (ATP Automatic Train Protection) will be built for the Helsinki Metro. It will continuously monitor the train’s speed- distance profile, and thus prevent the emergence of dangerous situations in advance. The ATP is also responsible for such functions as the continuous and more precise location determination of the trains.
In the automatic operation, the ATP system is also responsible for the so-called "train protection”, in other words, it prevents the emergence of the collisions. This is additionally explained in connection with the automatic metro’s transportation.
Automatic Train Operation (ATO)
The ATO (Automatic Train Operation) ultimately makes the metro automatic; it is responsible for running the train. The ATO controls all of the train’s movements and other functions. The running is optimized in such a way that the ride is as smooth, punctual and energy efficient as possible.
All metro stations will be equipped with platform doors, which, together with an encircling glass wall, will fully separate the platform area from the track area. The platform doors will only open after the train has stopped.
The present doors are 170 cm high and shaped like ports. Fully-sized doors will be built for the new sections of the Western Metro Extension.
In the event of emergencies, the glass wall between the platform doors will be removable, which aids the emergency services in gaining access to a stopped train or the track area.
A basic picture of the platform doors
Other Equipment and Systems
For the automatic metro, both the track and the trains will be equipped with many new equipment. A two-way radio data transfer system will be built between the trains and the ATC-track devices
The stations will receive new display boards, which will display the arrival times of the next two trains. The texts of the displays will be more visible than at present, and they will be able to be utilized to transmit additional important information. Additionally, video surveillance will be extended to the trains and the metro’s control room facilities will be renewed.