OK, so it's a bit of a guess as this is not my area of expertise at all, but as far as I can see per google searches, the "materiell" in question are train components (locomotives, carriages etc)

See: http://jernbaneforskning.no/files/pages/554/2002-fodstad-asc...

"Rolling stock" seems to be the equivalent in English:
http://pubsonline.informs.org/doi/abs/10.1287/trsc.2015.0633...