The hoosac tunnel is unusual in that the lining changes part way thru the bore.
The western end was lined with brick. The western end was raw rock. it is not possible to do this with a
single tunnel spline in Trainz however two separate tunnel splines with the same basic dimensions, track
spacing, etc will connect and the connected ends dissapper. There is a screen shot in the folder taken in
surveyor showing the complete tunnel including the door at the eastern end after assembly.