Most freight trains drives on the corridors Kijfhoek - Emmerich (the "Betuweroute") and Kijfhoek - Venlo.
Kijfhoek - Venlo was an important corridor until the "Betuweroute" opens in 2007.
When you take a visit to Zwijndrecht you will see some freight trains for sure, but it could be a little bit disappointing in comparison with a few years ago.
Other lines with a few freight trains a day are Kijfhoek – Amersfoort - Bad Bentheim and Amsterdam – Emmerich.
On the website RolandRail (http://rolandrail.net/drgl/dltdr.html
) you could find some timetables of Dutch freight trains. Please note that those timetables are theoretical, trains could be cancelled, delayed a few hours or drive earlier.
Explanation of the abbreviations used in the timetable you could find at http://rolandrail.net/drgl/afko.htm
Two years ago I made a list of all freight trains passing Zwijndrecht. You could find this list at http://spoorpunt.nl/Passeerlijst_Zwd_Ddzd.pdf
but please note that it isn’t actual however there isn’t changed a lot.
When you especially look for class 66 loco’s, they are operated by Captrain, Crossrail, Rurtalbahn and RheinCargo at this moment. A few saturday-trains which are mostly hauled by a class 66:
Captrain 47715 Essen (Belgium) 09.08 Roosendaal 09.17 Kijfhoek 09.59
Captrain 49526 Emmericht 11.57 Kijfhoek 13.00/13.42 Maasvlakte 14.42
RheinCargo 41785 Maasvlakte RSC 17.42 Maasvlakte 18.12/18.27 Kijfhoek 19.24
RheinCargo 47710 Emmerich 14.49 Arnhem 15.21 Utrecht 16.34 Amsterdam 17.15
RheinCargo 48506 Emmerich 12.52 Arnhem 13.21 Utrecht 15.34 Amsterdam 16.15
RheinCargo 48507 Maasvlakte 7.27 Kijfhoek 8.24/8.34 Emmerich 10.24
RheinCargo 48507 Emmerich 21.02 Kijfhoek 22.32
RheinCargo 48518 Emmerich 18.01 Utrecht 19.34 Amsterdam 20.15
RheinCargo 49700 Emmerich 7.13 Kijfhoek 8.40/9.00 Maasvlakte 9.59
RheinCargo 49701 Maasvlakte 14.48 Kijfhoek 15.44
Please note that the RheinCargo trains are often hauled by a Traxx DE instead of a class 66.