Sentence:  A surprisingly technical question from the audience on the possibility of working coal traffic in more substantial <WSD>trainloads</WSD> from pit to power station elicited the answer that the N.E.R. had hopes of more circuit working with specially designed high-capacity wagons on the style of the bogie 56-tonners used for the ore traffic between Tyne Dock and Consett, [...]. 
Meaning of the word marked with <WSD> tags:  The amount that can be transported by a train.