Good afternoon,
for those with plans for visiting DUS: the airport website has announced that the visitors terrace is closed since October 27th, 2014 on behalf of of (re)building activities and security measures.
They think re-opening could be halfway December 2014 but the final date will be announced on the website. To soften the blow the entrance fee then will be half the normal price until January 15th, 2015.
Nothing is mentioned any more about the railway station terrace. One can assume that closure of that facilty then will be definitive.
Cheers, Ab Gobets.