No DumDum Railway station is far form Airport. There is a station inside Airport Complex Biman Bandar but there are less trains. Forget Trains. Just Try to Get a cab as fast as you can or else pre book i.e Uber/Ola etc. Just Tell the Cabbie to Go Via CIT Road-Manicktala Road and Finally get into Acharya Jagdish Chandra Road. It will take around 30-40 mins at that time.Although Cab driver will himself take you via these roads but make sure that you say mention the way to him. Dont Worry You will even have plenty of time to kill at Sealdah. :)