Drivers who travel through Prospect Park will have to find an alternate route.
Cars are now banned on Prospect Park's West Drive from Grand Army Plaza to Park Circle.
The eastern side would also be closed to traffic, except for a two-hour window between 7 a.m. and 9 a.m. on weekdays.
The city says the ban makes the park safer for bikers, runners and pets.
Parkgoers we spoke with had mixed reactions.
"We have more accessibility, more flexibility in doing what we have to do in the park," said one parkgoer.
"I think it's a lot more tranquil out here," said another.
"Bikers, in my opinion, feel as though they own the entire road," said a third.
Last week, similar restrictions went into effect in Central Park. Cars are now banned there below 72nd Street.
Prospect Park and Central Park were already car-free on weekends.
The DOT says there's a possibility of banning traffic from both parks completely, but the department says it would require more studying.