Reconstruction of the Kaunas Railway Tunnel

During reconstruction of the Kaunas railway tunnel built in 1861 a 108-metre long section of the tunnel was rebuilt, the power supply, signalling and emergency lines were renovated, security systems were installed; lighting was renewed, and a drainage system to collect groundwater from the tunnel vault was constructed. After reconstructing the portals their historical view was restored. The tunnel is 1285 metres in length, 6.6 metres high and 8.8 metres wide. The repair of the tunnel may be considered as one of the most complicated from the engineering point of view not only in Lithuania but also in the other Baltic countries. One of the most complicated repair works was the widening of the tunnel’s cross-section. When concreting the vault of the tunnel a formwork was used produced especially for the cross-section of the tunnel. Having finished the concreting of the first stage the formwork with the help of hydraulic equipment was loosened from concrete surface and moved to the other concreting stage using a temporary railway track. A special bentonite “carpet” was laid in the tunnel under the railway track structure which would protect groundwater from the spillage of petroleum products during the accident. After reconstruction a modern fire-fighting system with special sprinklers was installed in the tunnel. It will ensure an efficient power of fire extinguishing in case of a train fire in the tunnel. The new communication system makes it possible to call for help in case of an emergency. Communication stands are adapted for the disabled and are resistant to high temperatures. Before reconstruction there was no lighting in the tunnel. The current lighting system meets all the requirements for tunnels. The reconstructed sections of the tunnel will allow all the travellers to get acquainted with the original view of the tunnel after it was constructed and before the final reconstruction. After reconstruction the tunnel operation was improved, the train traffic safety was increased. The tunnel was excavated on a 30-metre high hill, under the Aukštieji Šančiai residential district. Before the World War II the tunnel had two rail tracks, and after the war and until now – one rail track.