The Rantatunneli project was started in 2013 and will be completed in 2017. The project will reroute just over four kilometers of Highway 12 and a new residential area, Ranta-Tampella, will be created. Ranta-Tampella will be a prime lakeside real estate area for around 3,600 residents, offering uninterrupted views of Lake Näsijärvi. The highway will pass under the city through a new tunnel, which will be the longest road tunnel in Finland, at 2.3-kilometer in length.
Tampere is located on a narrow strip between two lakes, and is the most populous inland city of the Nordic countries. By rerouting the highway the city not only gains the space where the road used to pass, but also grows because the rock material generated during the tunnel excavation has been used to fill in the water body. In total, the central Tampere area grows by 4.5 hectares, including also a new park in the Ranta-Tampella district.
Building and maintaining tunnels and their electric networks come with numerous challenges. One of the most important ones is that power must be supplied at all times to ensure a safe environment - ensuring that there is air ventilation and light and that the traffic control system stays up at all times.
To ensure that power is distributed without any interruptions, while optimizing available space in the tunnel, ABB installed modular UniSec switchgear, which can be scaled easily to accommodate future expansion, and the very compact SafePlus switchgear.
To protect, control, measure and monitor the network throughout the entire tunnel, ABB's Relion® 615 series protection relays were installed. The role of the protection relays and the MicroSCADA Pro local distribution control system is to provide a stable, uninterrupted energy supply in the tunnel. Protection relays quickly locate the faults to isolate them to a limited part of the network, and immediately send information about the type of fault to the remote central control system. If there is a complete outage from the external power supply, the protection relays give a start command to activate the reserve power system. The restoration of the power distribution grid in the tunnel is then automatically done in the MicroSCADA Pro system.
To ensure reliability and power system performance, the solution relies on horizontal GOOSE-based communication technology. GOOSE (Generic Object Oriented Substation Events) is part of the IEC 61850 standard for power system automation.