Before the new City Hall master tower was built, there was a provision at the north end of the upper level for a diamond crossover (which has existed since the construction of this station, when the upper level platform was to be a terminal) which is now occupied by a relay room. At the south end of the station, the uptown track curves away from the wall; this dates from the original construction when the upper level was converted from a terminal, with presumably a straight line, to a through station with a single two-track tunnel.