As Mayor Bloomberg yesterday downplayed threats of a taxi strike scheduled to begin this morning, several city agencies unveiled a contingency plan in the event that a considerable number of yellow cabs will sit out today’s commute. The plan, which calls for extra police and flat rates for group rides similar to those used during the transit strike of 2005, took effect at midnight and will continue throughout the planned two-day strike unless the Taxi and Limousine Commission says the work stoppage is not significantly disrupting service.

It was not clear yesterday how many taxi drivers would take part in the strike planned by the New York Taxi Workers Alliance, which represents about 10,000 of the city’s 44,000-plus drivers. Mr. Bloomberg and leaders of two other taxi unions said they did not expect a significant number of drivers to follow through with the strike threats.

Representatives from the taxi workers alliance and leaders of the city’s other labor unions gathered one last time before reporters yesterday to gather support for the strike. They argue that global positioning systems and credit card machines that are being implemented in taxis will be used to track drivers and also will force cabbies to pay a percentage of the credit card fee.

“Drivers are ready to strike,” the executive director of the alliance, Bhairavi Desai, said. “No one needs to twist any arms.”

Responding to allegations that cabbies behind the strike have been intimidating other drivers into joining them, the police department will assign extra police officers to transportation hubs and taxi garages.

“We are taking these steps to ensure the public safety and to guard against reprisals against cabbies who elect to drive,” the police commissioner, Raymond Kelly, said in a statement.

Riders taking group taxis to the airports from Manhattan will be charged $30 for trips to John F. Kennedy International Airport and $20 to La Guardia International Airport.

For other group riders, the city has created eight zones: four in Manhattan and one in each other borough. Rides will cost $10 a person, plus $5 for crossing into each new zone.

The TLC could allow residents to hail livery cabs if it deems it necessary.

Representatives from several city car services said they saw no spike in reservations for private cars yesterday.

“No one knows if there is going to be a strike,” a manager at Paris Limousine Service, Michael Suratta, said.