From ASFINAG, the Austrian highway company public release:

ASFINAG began extensive renovations on six galleries on the S 16 Arlberg expressway between Flirsch and St. Jakob am Arlberg last year. The work primarily involves the repair of concrete and asphalt damage, road crossings, and the expansion of safety features.

Renovations and expansions will then take place between Pettneu and St. Jakob starting May 19. As a result, partial closures are planned, and a two-way traffic section will be established between the Ganderbachgalerie and the Malfonbach Tunnel. During this time, there will be disruptions at the Pettneu junction. Between May 19 and July 21, the exit ramp from Bregenz to Pettneu and the exit ramp from Innsbruck to Pettneu will remain closed. From July 22, the exit ramp from Innsbruck to Pettneu will remain closed, as will the entrance ramp from Pettneu towards Innsbruck.

All work is scheduled to be completed by September 2025, and ASFINAG is investing €33 million in improving road safety.

source: https://www.asfinag.at/ueber-uns/presse/pressemeldungen/fortsetzung-sanierung-galerien-flirsch-bis-st-anton/