In the mid-nineteenth century, work began on a crucial section of the railway line connecting Boston to the Hudson River. The addition would【A1】______from Greenfield, Massachusetts, to Troy, New York, and it required tunnelling【A2】______Hoosac Mountain, a【A3】______impediment, nearly five miles thick, that blocked the【A4】______between the Deerfield Valley and a tributary of the Hudson. James Hayward, one of New England’s leading railroad engineers, estimated that penetrating the Hoosac would cost,【A5】______, a very manageable two million dollars. The president of Amherst College,【A6】______geologist, said that the mountain was composed of soft rock and【A7】______tunnelling would be fairly easy【A8】______the engineers had breached the surface. “The Hoosac is believed to be the only barrier between Boston and the Pacific,” the project’s promoter, Alvah Crocker, 【A9】______ Everyone was wrong. Digging through the Hoosac turned out to be a【A10】______. The project cost more than ten times the budgeted【A11】______If the people involved【A12】______the true nature of the challenges they faced, they would never have funded the Troy-Greenfield railroad.【A13】______, had they not, the factories of northwestern Massachusetts wouldn’t have been able to ship their goods so easily to the expanding West, the【A14】______of freight would have remained stubbornly high, and the state of Massachusetts would have been【A15】______poorer.