The existing Učka tunnel is 5062 meters long and was built in the form of a single tunnel tube with two-way single-lane traffic. In the continuation of the Učka tunnel itself, on the Istrian side, there are also two shorter single-tube tunnels with two-way single-lane traffic. These are the Zrinščak I tunnel (200 m) and the Zrinščak II tunnel (50 m).

The project envisages the construction of a second left tunnel pipe with a length of 5634 m, which will be run approximately parallel to the existing one. The existing right and the newly built left tunnel tube will be connected to each other by cross passages for pedestrians, cross passages for vehicles as well as cross passages for emergency vehicles. Traffic through each tunnel tube will be one-way and two-lane.

For the constructions need of the second left tunnel tube of the Učka tunnel, on the section Vranje – Učka Tunnel – Kvarner Portal, as part of AC Istarski ipsilon – A8, CTP PROJEKT created the Elaborate on fire protection of the tunnel under construction.