The earthquake-active Hayward Fault bisects the tunnel about 900 feet (270 m) inside the west portal (Oakland side).

There is a ventilation structure at the east portal with roll-down doors that can close off the tunnel end to allow air to be sucked out or blown in.

[4] The work, which includes excavating the tunnel walls and realigning the tracks, is expected to cost $60 million.

[7] Material removed in the construction of the tunnel was used as fill for a concurrent expansion of the Port of Oakland.

[8] On December 4, 2013, a BART train suffered mechanical braking problems and made an emergency stop in the tunnel near Rockridge station.