Mayor Michael Bloomberg announced plans yesterday to curtail vehicular traffic on Central Park's East and West drives, and Prospect Park's West Drive - at least temporarily.

"For many years, people coming to Prospect Park and Central Park for recreation during weekdays have had to share road space on the park drives with automobiles," Bloomberg said. "It hasn't always been an easy relationship."

Under a sixth-month pilot program, Central Park's West Drive in Manhattan will be open to cars only during the 7 to 10 morning rush hour, while the East Drive north of 72nd street will be open to vehicles only from 3 to 7 p.m. Now, both the East and West drives are open to traffic only during the morning and evening rush hours. In Prospect Park, in Brooklyn, cars will not be allowed during the morning rush hour on West Drive. The changes are effective June 6.

"It will be more of a haven than ever before," said Parks Commissioner Adrian Benepe.

In the past, however, closing the park to vehicular traffic has met with protests from cab drivers, who use the roads to beat traffic on Fifth Avenue and Central Park West.

"They should have exemptions for taxi cabs," said Bhairavi Desai, of the New York Taxi Workers Alliance. "Not only will drivers have to face more congestion in order to pick up fares, but also to complete fares."

But to Councilman John Liu (D-Flushing), chairman of the transportation committee, the program isn't enough. "Why allow cars in Central Park at all? The park loop simply is not and should not be a part of the city's street grid," he said in a statement.

Paul Steely White, executive director of Transportation Alternatives, prefers a pilot program eliminating car access for the whole summer. "Clearly, New Yorkers want more car-free space, particularly in the summer," he said. "With this flip-flop closure scenario, I think he'll create unnecessary confusion."

Staff writer Melanie Lefkowitz contributed to this story.