When the tunnel equipment no longer fulfils the needs of the operator or the tunnel users or when the requirements of legislation or the characteristic of the traffic has changed, it may be necessary to upgrade the tunnel.
The need for pre-planned work can be the consequence of, for instance, new regulations or opportunities to improve equipment, its functionality, safety or energy-efficiency, or to reduce preventive maintenance requirements. There may be a further occasional need to replace equipment due to age deterioration. Major work will usually be treated as special projects.
Activities may include:
This chapter of the Manual is broken down into six pages: