In this Friday, Feb. 20, 2015 photo travellers leave a BVG subway train in Berlin, Germany. Berlin is unveiling a new app that will let people use public transport, rental bikes, car-sharing and taxis seamlessly to travel through the German capital. (Lukas Schulze/dpa via AP)

Travelers in Berlin will soon be able to use a single app to switch seamlessly between public transport, rental bikes, car-sharing and taxis without signing up for each service individually, officials said Monday.

Lithuanian startup Trafi said Berlin will be the first major European capital to get a transport app that handles billing for all services centrally and requires only a single login. Similar services are already available in Vilnius, Rio de Janeiro and Jakarta.

So-called 'deep integration' apps, which remove the annoyance of dealing with multiple providers, are seen as important for cities trying to prevent people from clogging up congested roads with their own cars.

"This goes in precisely the right direction," said Andreas Knie, a mobility expert at the Social Science Center Berlin. "Transport services need to be connected, just like cellphone networks, so you can easily roam from one to another."

Berlin's aging transport system—a maze of underground lines, trams, buses and commuter rail covering an area the size of Dallas—is straining as its population heads toward 4 million.

The capital's left-wing government has struggled in recent years to integrate new services such as ride-hailing firms, car-sharing companies, free-floating bikes and scooters into the existing infrastructure, some of which dates back to the 19th century.

Knie was skeptical that large transport companies like Berlin's publicly owned BVG, which counts more than a billion passengers a year, are willing to do anything that might endanger their business model.

It wasn't immediately clear whether smaller companies will get an equal footing in the app, including to valuable real-time data on how customers are moving through the city.

Two large car-sharing companies, Daimler's car2go and BMW's DriveNow service, and ride-hailing giant Uber are notably absent from the starting lineup, though more than a dozen smaller rivals are already on board.

Trafi said more are expected to join by the time the app, called Jelbi, launches this summer.