Environmental activists protesting car culture disrupted traffic on several highways around Munich before the opening Tuesday of a leading auto show in the German city.

Demonstrators unfurled banners with slogans such as “Block IAA,” in some cases abseiling from highway bridges to do so, news agency dpa reported. At one location, they pasted over a highway sign with the words “Smash Car Lobby & Industry.”

Police and fire service officers ended the protests, and the affected stretches of autobahn were reopened by lunchtime. More protests are expected on Friday, though organizers haven’t specified what exactly they plan to do.

The IAA Mobility fair, which takes place every two years, was opening later Tuesday. The event is held every two years and is in Munich for the first time this year.

It previously took place in Frankfurt. The show moved after the German Association of the Automotive Industry changed the concept of the show to change its focus and include more discussion of environmental issues, new technologies and innovation and other modes of transportation including e-scooters and bicycles.