Last Wednesday, November 25th, the second stall was successfully completed in the emergency gallery of the Zarátamo tunnel. In this way, the excavation of the first gallery, with a length of 728.30 meters, and which is one of the 7 galleries that are planned to be executed in the works: “New emergency galleries in the tunnels of the Vitoria-Bilbao-San Sebastián high-speed line. Section: Vitoria-Bilbao”, where the UTE Esteyco-Team carries out the work of the ACO (Assistance for Works Control) for ADIF.
This second stall was made when the two execution fronts (fronts 3 and 4) were found, from the entrances called junction 1 and 2, by means of excavation and support of the complete section. A month and a half ago, the first planned stall was made when fronts 1 and 2 of the excavation were found, which communicated the opening with the junction 1.
The works are necessary to comply with the European Standards that require a maximum distance of 1,000 meters between the safety areas in railway tunnels. Since the tunnels were already finished before the approval of the regulations mentioned, it is necessary to adapt them, by providing them with emergency exits.
A total of 7 emergency galleries will be built parallel to the corresponding tunnels, with a separation of 30 meters between the axis of the main tunnel and the axis of the gallery. The lengths of this galleries vary between 73 m and 1,410 m of the longest. The 25 m2 section allows the circulation of medical and emergency vehicles inside.
The excavation method is the full section NMA (New Austrian Method), establishing different kinds of support depending on the quality of the rock mass:
Type I section, for fields with RMR> 45. 3m pass, gunite with a thickness of 10 cm, 13 Swellex type bolts of 3m.
Type II section, for fields with 25 < RMR > 45. 2m pass, gunite with a thickness of 17 cm., 17 Swellex type bolts of 3m and TH-21 type trusses every meter.
SG-B type section, for fields with RMR <25. 1m pass, gunite with a thickness of 20 cm, 4 Swellex type bolts of 3m and HEB-160 type trusses every meter.
Finally, waterproofing is made up with a 2 mm thick PVC sheet and a 20 cm finish in the coating. With HM-30 concrete with a fiber content of 2.5 Kg / m3. The bottom slab is made of the same type of concrete with a thickness of 30 cm.
The works have been awarded to the company Obras Subterráneas, for a total amount of 25,220,115€ to be carried out in 27 months.