Note the variation in the shape of repeating letters. Handlettered in a popular Art deco style.
This is shown in a font by Jacob Erbar released in 1927 as Erbar Grotesk Garnitur

Unfortunately, the digital versions of Erbar Grotesk are more conventional.
There are some digital fonts with some similarity to the Plakat lettering, such as Neutraface bold from House Industries http://www.houseind.com/fonts/neutraface
Don

Edited:
Today's Trivia -- addressed mainly to English speaking readers.
Berlin Alexanderplatz is an amazing novel by Alfred Döblin, published in 1929. It relates the story of Franz Biberkopf, an ex-convict, who has to deal with misery, lack of opportunities, crime and the imminent Nazism lived in Germany during the 1920s. During his struggle to survive against all odds, life rewards him with an unsuspected surprise but his happiness will not last as the story continues. http://en.wikipedia.org/wiki/Berlin_Alexanderplatz.
I have no information on the 1931 movie.
Berlin Alexanderplatz was made into a film mini-series for West German TV in 1980. http://en.wikipedia.org/wiki/Berlin_Alexanderplatz_%28miniseries%29
I first saw in it the 1980s as a film art house series running about 16 hours. Its now available on DVD and includes English subtitles. I highly recommend it as a compelling story and character study.
Regrettably, The publicity for the mini-series did not use this period appropriate lettering.
Don

Thanks

Yes, Toronto Subway -- suggested by Ryuk -- has some good fit letters, particularly the _R_.
Don