Last Monday, September 28th, the first breakthrough was successfully completed in the emergency gallery of the Zarátamo tunnel. This gallery has a length of 728.30 meters and 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 Sebastian high-speed line. Section: Vitoria-Bilbao “, where the UTE Esteyo-Team carries out the Work Control Assistance for ADIF.
The first breakthrough was performed when the two execution fronts met, by excavating and supporting the entire section of the fronts from the outlet and junction number 1. Within a month and a half, a second breakthrough is scheduled, when the two new fronts executed from junction number 1 and junction number 2 meet.
The works are necessary to comply with European legislation requiring a maximum distance of 1,000 meters between safe areas in railway tunnels. Since the tunnels were already finished before the approval of these regulations, it is necessary to adapt them with emergency exits.
A total of 7 emergency galleries will be built parallel to the corresponding tunnels, with a separation between the axis of the main tunnel and the axis of the gallery of 30 meters. The lengths of these vary between 73 m and 1,410 m of the longest. The 25 m2 section allows the circulation of medical and emergency vehicles.
The excavation method is the full section NAM (New Austrian method), establishing different types of support depending on the quality of the rock mass:
Section type I, for soil with RMR> 45. 3m pass, gunning with a thickness of 10 cm, 13 bolts type Swellex of 3 m
Section type II, for soil with 25 <RMR> 45. 2m pass, gunning with a thickness of 17 cm, 17 bolts type Swellex of 3m and TH-21 trusses every meter.
SG-B type section, for soil with RMR <25. 1m pass, gunning with a thickness of 20 cm, 4 bolts type Swellex of 3m and trusses type HEB-160 every meter.
Finally, it is established a waterproofing with 2 mm thick PVC film, and a finish in the coating of 20 cm. of 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, with a total amount of € 25,220,115 to be carried out in 27 months.