Karawanken Tunnel's €570M upgrade transforms Austria-Slovenia travel

New Karawanken Tunnel Tube Opens After Over Seven Years of Construction

The new tube of the Karawanken Tunnel was officially inaugurated on Wednesday after more than seven years of construction. The approximately eight-kilometer-long border tunnel connects the Karawanken Autobahn (A11) south of Villach with Slovenia's motorway network, specifically the Avtocesta 2 leading to Ljubljana.

For the next few years, traffic in the new tube—just as in the old one—will run in two lanes with bidirectional flow. Only from 2029, once the old tube has undergone a complete overhaul, will this change.

Following the tunnel's opening to traffic, preparations for rerouting will begin, according to Austrian motorway operator Asfinag. From March 20, northbound traffic will flow through the new east tube, and no later than a week after that, traffic from Austria to Slovenia will also be shifted from the existing west tube to the new one, operating in bidirectional mode.

How Much Was Invested

Asfinag invested €191 million in the new Austrian section of the tunnel, while the overhaul of the old tube will cost an additional €123 million. The full expansion, including the renovation, will cost Asfinag and its Slovenian counterpart, Dars, around €570 million in total. The EU contributed €3.35 million for planning and €9.4 million for construction.

Construction of the new east tube faced some delays. Slovenia encountered difficulties with contract awards, and hydrogeological conditions—particularly on the Slovenian side—posed significant challenges.

1.5 Million Tons of Excavated Rock

On the Austrian side, the tunnel—built by a consortium of Swietelsky Tunnelbau GmbH & Co KG and Swietelsky Baugesellschaft m.b.H.—was structurally completed in autumn 2023. Excavation alone for the Austrian section produced 1.5 million tons of rock. The mountain water, flowing at 600 liters per second, is harnessed by a small hydroelectric plant to power the tunnel's systems.

Since mid-2025, safety installations have been added. The new east tube features cross-passages to the old tube every 330 meters, serving as emergency escape routes. Once fully upgraded, the Karawanken Tunnel will meet the latest safety standards, including ventilation, lighting, traffic sensors, and video surveillance.

Switching to Temporary Bidirectional Traffic

In the event of a disruption, such as an accident, the system will switch to temporary bidirectional traffic within minutes. Automated pivoting concrete barriers will be installed at the tunnel portals to manage this.

With the full expansion, traffic jams and border congestion are expected to become a thing of the past. Hartwig Hufnagl, a member of Asfinag's executive board, stated: "In a few years, this bottleneck between Austria and Slovenia will be history. The full upgrade will put an end to the frequent congestion—especially in summer—that has plagued this route. The new tunnel tube we are opening today is the first step toward that goal."

A toll is required to use the Karawanken Tunnel. The current fee of €9 per passenger car will remain unchanged, except for inflation adjustments.

Tunnel Was Once a Battleground

The original Karawanken Tunnel—the west tube—was constructed between 1986 and 1991. Shortly after its opening, it became a warzone. During Slovenia's Ten-Day War in June 1991, units of the Yugoslav People's Army briefly occupied the tunnel. Fighting broke out, and combat aircraft strafed the southern portal. Within days, Slovenian Territorial Defense forces reclaimed the border crossing.