The main railway tunnel hosts two 107m long junction caverns within the area of the Imperia Station.The first is located at a distance of 100m from the Imperia portal site.The caverns have a 25.9m span and cross-sectional areas of 345m2.They are connected to each other by a three-track,non-symmetrical tunnel section.A single track tunnel also lies along the first cavern.The tunnels have been excavated in flyschs of fair rock mass quality and have overburdens of about 130m.The design of the excavation sequence,the support measures and the dimensioning of the lining system were based on numerical modelling.The support system consists of heavy steel sets that are connected to the rock mass by 8m-long swellex bolts and 30cm of shotcrete.Fibreglass bolts were used to pre-reinforce overstressed zones and as forepoling in the tunnel crown area.Excavation proceeded according to a top-heading and bench scheme.Invert excavation and casting the lining is currently under progress.