What is the importance of Friedrichstrasse Station in the novel, The Wall Jumper?

Friedrichstrasse Station is the main entry point into East Berlin for travelers from the West. Friedrichstrasse marks the end of the S-Bahn, the suburban transit system of the German National Railway. On his first extended trip to the DDR, the Narrator notes that passengers look more like their relatives the closer they get to the Wall. Everyone and everything seems some tint of gray. Passengers line up first thing at the Intershop kiosk to buy liquor and cigarettes. On the station's exterior "traveling headlines" (pg. 39) are displayed.