37906 passes Marshfield on 27 August 1998 with the 6Z52 11:05 Cardiff Docks to Llanwern slag empties. This short term freight flow used MEA wagons to transport blast furnace slag from the steel works to Cardiff for use in the construction of the Cardiff Bay Barrage. Due to the weight of the material the train was diagrammed for a Class 37/9 and these workings turned out to be something of a swansong for this small sub-class, with the non-standard nature of the locos leading to their withdrawal the following year.