If you’re flying to Vienna in the coming months and are used to taking the green City Airport Train from the airport into the city, you’ll find a very different CAT waiting for you. For now, the City Airport Train isn’t a train at all—it’s a bus. And this isn’t a short-term replacement: CAT buses are scheduled to operate until the end of October 2027.
The reason is a massive construction project on Vienna’s main S-Bahn railway corridor through the city. Starting September 7, 2026, the section between Wien Praterstern and Wien Hauptbahnhof (Vienna Central Station) will be closed for approximately 14 months.
Viaducts, bridges, stations, platforms, tracks, and other railway infrastructure are being rebuilt or modernized. It is one of the most extensive railway projects Vienna has seen in years.
For the CAT, however, the disruption started even earlier than planned. Following a cable fire near Wien Praterstern, train services had to be adjusted in August. As a result, CAT by bus has been operating between Vienna Airport and Wien Mitte since August 24, 2026.
CAT by bus runs directly to Wien Mitte
The good news for travelers is that surprisingly little changes when it comes to the CAT’s destination.
The replacement buses operate directly between Vienna International Airport (Flughafen Wien) and Wien Mitte/Landstraße, the same transportation hub where the regular CAT trains normally arrive.
There are no stops along the way.
Comfortable Setra coaches operated by Blaguss are being used for the replacement service. During the daytime, buses can actually run more frequently than the regular CAT trains. Between approximately 7:00 a.m. and 7:00 p.m., departures are scheduled as often as every 12 minutes. Early in the morning and in the evening, buses generally operate at 15-minute intervals.
The scheduled journey takes approximately 21 minutes.
That means CAT is trying to retain its biggest advantage during the construction work: a simple, nonstop connection between Vienna Airport and the city center.
How long will CAT operate as a bus?
According to the current schedule, CAT by bus will continue through October 31, 2027.
Only after that is the city airport train expected to return to the tracks.
In practical terms, this means that almost everyone flying to Vienna between now and fall 2027 should be prepared for the temporary bus service.
CAT is also using the lengthy interruption to make a major upgrade. When train service resumes in fall 2027, new Stadler double-decker trains are expected to enter service.
CAT by bus ticket prices
A regular one-way CAT by bus ticket currently costs €14.90. A round-trip ticket costs €24.90.
Discounts are available for certain travelers, including holders of a KlimaTicket, Wiener Linien annual pass, and ÖBB Vorteilscard. Children up to age 15 can travel free under the applicable CAT conditions.
There is one important detail to remember: a CAT ticket is not the same as a regular Vienna public transportation ticket.
Even though you are now boarding a bus instead of a train, CAT by bus remains a separate airport transportation service. A regular Wiener Linien ticket does not automatically include the CAT.
City Check-In temporarily unavailable
One of the CAT’s most distinctive services is temporarily disappearing.
Normally, passengers flying with participating airlines can check in for their flight and drop off their luggage at the City Air Terminal at Wien Mitte before traveling to the airport.
CAT City Check-In is not available during the railway closure.
If you’re flying out of Vienna, you’ll therefore need to take your luggage with you to Vienna Airport and check it in there.
The S7 airport train is also affected
The construction work has much wider consequences than just the CAT.
Vienna’s S-Bahn Stammstrecke is one of the city’s most important railway corridors. From September 7, 2026, through the end of October 2027, the central section between Wien Hauptbahnhof and Wien Praterstern will be closed.
This also affects the inexpensive and popular S7 service to Vienna Airport.
During the main closure, the S7 will no longer operate along its usual route through Wien Mitte. Instead, S7 trains will start and terminate at Wien St. Marx.
From St. Marx, passengers can connect to other parts of Vienna using public transportation, including tram lines 18 and 71.
Another option is the REX 7 regional train. This service will be rerouted via Wien Hauptbahnhof and will continue toward Vienna Airport.
Railjet and other long-distance trains between Wien Hauptbahnhof and Vienna Airport will also continue to operate.
What is the best way to get between Vienna Airport and the city?
That largely depends on where you are staying in Vienna.
If your hotel or apartment is around Wien Mitte, Landstraße, or close to the U3 or U4 subway lines, CAT by bus remains a particularly convenient option. You can board at Wien Mitte and travel nonstop to the airport.
If you are staying closer to Wien Hauptbahnhof, we would not recommend traveling to Wien Mitte just to take the CAT bus. Direct trains between Vienna Central Station and Vienna Airport will continue to operate during the construction work.
Budget-conscious travelers can still use regular public transportation and ÖBB services, but planning your route will require a little more attention than usual. The familiar S7 connection through Wien Mitte will temporarily not be available.
In other words, don’t automatically follow an old Vienna Airport transportation guide you may have bookmarked. Routes that worked before September 2026 may no longer be the most convenient option.
Why is such an important railway line closing for 14 months?
The closure is part of ÖBB’s extensive S-Bahn Wien Upgrade.
Vienna’s main S-Bahn corridor is being modernized to accommodate more trains, longer trains, and ultimately significantly more passengers.
The project includes rebuilding viaducts in Vienna’s 2nd district, renewing bridges and retaining walls, extending platforms, and modernizing Wien Rennweg and Wien Quartier Belvedere stations. A large amount of railway infrastructure between Hauptbahnhof and Praterstern is also being replaced or upgraded.
CAT by bus: What travelers need to know
CAT train: Temporarily not operating
CAT by bus: Operating since August 24, 2026
Route: Wien Mitte – Vienna Airport, nonstop
Travel time: Approximately 21 minutes
Frequency: Up to 5 departures per hour during the day
Replacement bus service ends: Currently scheduled for October 31, 2027
S7 airport train: From September 7, no service via Wien Mitte; starts/terminates at St. Marx
Trains from Wien Hauptbahnhof: Direct airport trains continue to operate
CAT City Check-In: Temporarily unavailable