Sentence:  Research would be facilitated if a <WSD>test track</WSD> of suitable length and characteristics for coach running tests at speeds up to "90 m.p.h.-plus" were on offer, as there are obvious difficulties in making available a regularly used main line for such purposes; but B.T.C. plans in this respect have apparently suffered under the economy axe. 
Meaning of the word marked with <WSD> tags:  A railway track for the purpose of testing trains.