Once you've found it, this does not look hard. I think it took the fastest of us about 8-10 hours to get it. The problem was that everybody tried to decode the letters on the truck (The "station" hint only came later).

 

So, the solution is to decode the text on the door as follows:

 

It's two words, separated by "0".

 

XGJ ZWE XFP ZYP QQN XFJ QLJ XGC 

XHJ ZRP ZXA QRH XZT YMY XQE ZRZ TTK

 

Each word is composed from three letter train station codes:

XGJ: Cobourg railway station, Canada

ZWE: Antwerpen-Centraal railway station, Antwerp, Belgium

XFP: Malmö Central Station, Sweden

ZYP: Pennsylvania Station, New York City, New York, United States

QQN: Birmingham New Street railway station, Birmingham, UK

XFJ: Eskilstuna Central station, Eskilstuna, Sweden

QLJ: Lucerne railway station, Lucerne, Switzerland

XGC: Lund Central Station, Sweden

 

XHJ: Aachen Hauptbahnhof, Aachen, Germany

ZRP: Pennsylvania Station, Newark, New Jersey, United States

ZXA: Aberdeen railway station, Scotland

QRH: Rotterdam Centraal railway station, Netherlands

XZT: Trondheim Central Station, Norway

YMY: Montreal Central Station, Quebec, Canada (no longer an airport)

XQE: Ebbsfleet International railway station, Ebbsfleet Valley, UK (Eurostar)

ZRZ: New Carrollton (WMATA station), New Carrollton, Maryland, United States

TTK: Tottenham Hale station, London, United Kingdom (no airport)

 

 

The initial letters of the cities form the solution.