The Board Tree tunnel, I far as I know was never update and the "Old Main Line" also known as the "Fairmont Subdivision" and the tracks through Cameron were removed in the 1970's.
Freight (to Wheeling) was rerouted through the Short Line to New Martinsville in 1963.
Article "Memories of the Fairmont Subdivision" by Wilber Baker in The Sentinel, Nov/Dec 1988. a publication of the B&O Railroad Society.