Contracts for the installation of Mechanical and Electrical Systems

It will be constructed to be highly accessible, with sufficient redundancy for safety functions. A number of mechanical and electrical systems will be installed for operation and safety.

Safety

As a basis for the safety work associated with the Stockholm bypass, a safety concept has been developed. Its aim is to reduce the likelihood of accidents and decrease their impact. The safety concept incorporates administrative measures as well as active and passive safety systems, creating a robust safety system that can handle temporary disruptions, incidents and serious situations.

Two cornerstones of the safety concept are the separation of traffic in two one way tubes, and the principle of self-evacuation in the event of an accident or fire. The concept includes active safety systems such as: a fixed fire fighting system, lighting, a smoke control system, fire alarms, emergency phones, camera surveillance, emergency radio broadcasting (break-in radio), tunnel information signs, road signs and traffic lane signals.

Should a road accident, fire or other type of dangerous incident occur, the stretch of road affected will be closed temporarily and the traffic rerouted.

Control and Monitoring

The traffic in the tunnel system will be con-trolled and monitored twenty-four hours a day by Trafik Stockholm, the Swedish Transport Administration's Traffic Control Centre in Stockholm.

The personnel manning the Traffic Control Centre are assisted by a number of technical systems. With the help of cameras and sensors, the traffic controllers can monitor the traffic and, in the event of an incident or accident, alert and support the road assistance crews, police or rescue services.

Aided by the system, traffic controllers will also be able to direct and control traffic in the Stockholm bypass by reducing speed limits, closing lanes or initiating an evacuation of the tunnel system.

The Traffic Control Centre monitors, controls and directs traffic and facilities with the aid of a National Traffic Control Support system which is an advanced operator support system.

Operation Areas

The road facility will be divided into operation areas. Each operation area will cover 2,000 meters of one tunnel tube. This is a fundamental feature of the safety concept for the tunnels. Subdivision of the operation areas will provide a sectioning of the mechanical and electrical systems, which will limit the impact in each operation area in the event of an accident or loss of function.

The electrical power service stations will contain transformers and switchgears as well as other technical equipment for control and monitoring of the mechanical and electrical systems. They will be located in the rock space next to the traffic area.

Technical Equipment Locations and Technical Equipment Buildings

A utility culvert will run alongside the traffic area containing equipment for power supply, data and communication. This equipment will meet at integrated cabinets called Technical Equipment Locations. At surface interchanges, all equipment will be located in Technical Equipment Buildings. All electrical and signal equipment within an operation area will connect to Technical Equipment Building or to an electrical power service station via a Technical Equipment Location. This sectioning gives a decentralised facility, which also increases the efficiency of the installation and commissioning work.