Boston in Transit - The Book Figure 5.61 - A Renovated Second Level, March 1, 1913 A rapid transit train loading platform (top) and streetcar loop (left) were added to the second level of Sullivan Square Terminal in 1912. The loop expedited movement of streetcars through the upper level. Instead of pulling into one of the stub-end tracks on the east side and then reversing out, streetcars entered the reconfigured west side tracks, stopped once to discharge passengers, turned around via the loop, and returned to pick up passengers before exiting the terminal.