Growing coal sales to foreign countries in the early 20th Century increased train traffic between the southern West Virginia coal fields and shipping ports in Virginia. The Great Bend Tunnel eventually could not handle the heavier traffic efficiently because trains had to stop on each side and pass through one at a time. In 1930, the C & O Railway began constructing the Big Bend Tunnel to permit continuous east-west rail traffic, and the twin tunnels were used simultaneously until the Great Bend Tunnel closed in 1974. Over the 60 years between the opening of the Great Bend Tunnel in 1872 and the Big Bend Tunnel in 1932, tunnel-building techniques and technology advanced considerably. The early steam drill that John Henry defeated during construction of the Great Bend Tunnel evolved into reliable drilling systems, and an air compressor system like the one used here sent one line to the No. 1 eastern heading and another through the Great Bend Tunnel into the No. 2 western heading, with that line extending one and one-half miles.