TPF Getinsa Euroestudios (formerly Euroestudios) designed and supervised the construction of the Arlabán-Eskoariatza section of the AP-1 toll motorway. The project posed a major challenge due to the geotechnical and geological complexity of the area together with its high environmental value.

This motorway is part of the Basque Motorway Network, which links Vitoria to the Cantabrico Motorway. The route runs through an environmentally sensitive area of high geotechnical and geological complexity (major landslide events, slope instability, weak lithology with strong variations in thickness.) The main technical characteristics of the motorway are:

  • Paved dual carriageway with two lanes per carriageway. Carriageway width: 10.50 m. Length: 10.84 km of main motorway and 2.2 km of feeder roads. 3,905 km of tunnels and 1,924 km of viaducts. Design speed: 100 km/h.
  • Izuskitza Tunnel: 2 parallel tubes of 3,415 km length each. Excavation cross section: 108.8 m2. The tunnel crosses a karst area subject to major water inflows and some tunnel sections run across fault zones (normal faults and thrust faults). Construction method: New Austrian Tunnelling method.
  • Zarimutz Tunnels: 2 twin tubes of 499 m length. Excavation cross section: 102.1 m2. The New Austrian Tunnelling method and the Bernold method were used. The tunnel was bored in rock.
  • 6 viaducts
  • 3 overpasses and 5 underpasses
  • Fills of up to 65 metres in height and cuts of up to 60 metres.
  • 1 interchange (3 diamond slip roads and 1 trumpet slip road)
  • 1 toll area (7 booths, electronic toll collection system)


Provincial Government of Gipuzkoa

Project Dates


Project Figures

  • Project costs: 5,884,081 €
  • Construction value: 204,960,097 €