Phase 1 of the Southern Metropolitan Bypass (VSM) begins in Santurtzi (past the Ugadelbieta service area) and reaches Venta Alta (Arrigorriaga). It is divided into two sub-phases:
Phase 1a characteristics
The bypass has a trunk road with three lanes in each direction and a length of 17.8 km, half of which is built under tunnels.
In order to overcome the difficult terrain of the surroundings and to avoid the environmental and visual impact of the new road as much as possible, five tunnels have been built, all of them double tunnels: Argalario (2,150 metres), Mesperuza (708 metres), Santa Águeda (2,030 metres), Arraiz (2,273 metres), and Larraskitu (965 metres).
Alongside the trunk road of the VSM (AP-8), it has been necessary to build four new junctions: Ortuella – Portugalete – Trapaga (A-8, BI-3747, BI-3748, BI-3749), Galindo (Eje Ballonti), Kastrexana (BI-636/Corredor Cadagua), and Larraskitu – Buia (A-8, AP-68, BI-613/Miraflores).
Overall, the completion of the roads and junctions of the bypass required the construction of: 21 viaducts, five double tunnels, two cut-and-cover tunnels, four underpasses, three overpasses, with 11 existing overpasses and underpasses having been modified, and a pedestrian walkway has been built to connect the bicycle lanes of the Left Bank with those of the Zona Minera.
