The 6.44 km long highway, with separate dual carriageways the length of the route. A new link road connects the corridor with the N-636 near Muntsaratz, facilitating access to a new road to the towns of Abadiño and Atxondo.
A large part of the route runs through tunnels. Gaztelua I and II are two tunnels of 594 m and 1,141 m, respectively. Between them is a 216 m-long artificial tunnel also, and there is also a 95 m false tunnel at Atxondo.
The main work also includes two viaducts, 865 m and 649 m long respectively, serving as the basis for the connection of the new infrastructure to the AP-8. One of these branches off to another smaller viaduct, 187 m long.