Austria's Fern Pass road is to be closed on Saturday morning due to a demonstration, authorities said, warning of lengthy tailbacks on a key north-south route linking Germany, Austria and Italy.

The authorities are strongly advising drivers to avoid the area entirely. A similar closure at the end of June passed without major disruption, but this time the demonstration coincides with the start of the summer school holidays in the German states of Bavaria and Baden-Württemberg.

The demonstrators are protesting against the volume of traffic on the transit route. They are also critical of a planned tunnel intended to replace the most difficult section of the road, arguing it would only attract more traffic. They say around 20,000 vehicles already use the route on Saturdays.

Several hundred people are expected to take part in the protest. The closure also applies to the nearby Hahntennjoch Pass.

The state of Tyrol views the project favourably. It is due to begin in 2026-27 and be completed in 2030. The plan involves replacing 4.8 kilometres of mountain road with a 1.4-kilometre, three-lane tunnel through the Fern Pass. At the highest point of the 1,210-metre pass, drivers would need to navigate only 70 metres of altitude change inside the tunnel, compared with 200 metres on the current road.

The project is expected to cost at least €160 million ($184.25 million). The state of Tyrol says the tunnel will not increase the capacity of the route, particularly since the existing ban on lorries over 7.5 metric tons will remain in place.

The tunnel is part of a "Fern Pass package" that includes further construction measures. The package requires investment of at least €500 million in total. The corresponding loan is to be repaid from revenues from a future tunnel toll, which is set at €14.