A week after Central Park went mostly car-free, today marked the beginning of the permanent car-free zone on the west side of Prospect Park [PDF].

Leading up to today, the traffic shortcuts through Prospect Park had been gradually winnowed down to one lane on the west side during the evening rush and one lane on the east side during the morning rush, thanks to persistent advocacy. Campaigns in 2008 and 2002 each collected 10,000 signatures in support of a car-free park.

Before the de Blasio administration made the West Drive car-free, the most recent victory was a 2012 road diet that expanded space for pedestrians and cyclists on the park loop. Before that, the city closed the 3rd Street entrance to cars in 2009.

The job’s still not done as long as the park’s East Drive, which is closer to the less affluent neighborhoods on the east side of the park, continues to be a shortcut for car commuters on weekdays between 7 a.m. and 9 a.m. DOT says it is concerned that higher traffic volumes on the East Drive would lead to congestion in nearby neighborhoods if the park were made completely car-free.

Transportation Commissioner Polly Trottenberg, who marked the occasion this morning by walking her two beagles to a press conference in the park, said a permanently car-free East Drive could happen “at some point in the coming years.”

“Car traffic has continued to go down,” she told WNYC. “So we’ve done it in stages and we may be back again for the final phase.”