A lot of freight is likely to be 27000, some 36000. There should also be some Belgian and private open access locos (including Sheds?). Not sure if the Fret 67400 diesels are still doing the Lille Antwerp moves
Check out the blog of a model railway contact of mine (Jobiwan)
http://jobiwan.over-blog.fr/
who phots around the Lille area a lot. Traditionally, Dunkerque Lille is good for freight, with Dunkerque being the busiest port in France (I think it still is anyway) so somewhere like Armentières might be OK. However, lots of freight from Dunkerque (such as the one to Le Havre) will dive south at Hazebrouck towards Lens via Béthune, and thus not go to Lille, so a safer bet might be Hazebrouck. You will notice that Jobiwan often goes to Dunkerque itself, or the stations between Dunkerque and Hazebrouck, which suggests that he may prefer those locations to locations around Lille.
Lille Valenciennes used to be busy with all the freight on the Nord-Est route Dunkerque Lorraine, but the closure of traditional industries and the recession has made traffic volumes much less these days AFAIK.
Further afield , Somain used to be my yard of choice throughout the 1980s and 1990s but havent been there for a few years.
Try these maps:
http://www.bueker.net/trainspotting/map.php?file=maps/lille-area/lille-area.gif
http://www.rff.fr/cartes/
Gordon
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