In the early 1980s the railway built a new line and acquired another. The Tumbler Ridge Subdivision, an electrified branch line, opened in 1983 to the Quintette and Bullmoose mines, two coal mines northeast of Prince George that produced coal for Japan. It has the lowest crossing of the Rocky Mountains by a railway, at 3,815 feet (1,163 m). There are two large tunnels under the mountains: The Table Tunnel, long, and the Wolverine Tunnel, long. Electrified owing to the long tunnels and close proximity to the W. A. C. Bennett Dam and transmission lines, it was one of the few electrified freight lines in North America. Although initially profitable, the traffic on the line was never as high as initially predicted, and by the 1990s was under one train per day. The railway had incurred much debt building the branch line, and the expensive, unprofitable operations on the branch line could not help to repay that debt. In 1984 BC Rail acquired the British Columbia Harbours Board Railway, a line that connects three class I railways with Roberts Bank, an ocean terminal that handles coal shipments. Since the line had been constructed in 1969, it had been leased to the CPR, Burlington Northern Railroad, and Canadian National Railway in succession.