The rush hour commute was disrupted for many when BART closed and reopened two stations a combined seven times. The actions, which were deemed necessary to protect riders of the system, were nonetheless disruptive.
But the arrests mainly came from people failing to disperse when ordered by police and when protesters began blocking traffic on Market Street.
The protests were in response to the shooting death of a 45-year old man and the recent decision for BART to shut off cell service to disrupt other planned protests.
From the San Francisco Chronicle:
Authorities repeatedly closed two San Francisco BART stations during the Monday evening commute, arresting 45 people in connection with an anti-BART protest that roamed both aboveground along Market Street and inside the transit system.
Commuters were frustrated and confused, as BART officials closed and reopened the Powell Street station four times and the Civic Center station three times – sometimes within minutes – fearing that roaming protesters would disrupt transit service. The shifting protest also snarled traffic along Market Street.
Read the full article here.