The west end of the Hoosac Tunnel had doors which were normally closed to keep the
howling winds in winter from filling it with snow and ice. This done as a mocrosing and will open
at the approach of a train in 10 seconds. It will not automatically snap attach to the tunnel spline
so you must run a short (say 10 ft) section of track between them then (carefully) position it as
close to the west end as possible keeping the tracks in line (I tried it and its not that difficult).