Leaders of Philadelphia's striking taxi drivers ended their 48-hour strike a day early yesterday but promised to continue fighting problematic new high-tech dispatch and credit card systems mandated by the Philadelphia Parking Authority.

Leaders of the drivers and Parking Authority officials disagreed about how many cabbies stayed off the streets and about the strike's effectiveness. But officials of the authority, which since 2005 has regulated city cabs, said there was no shortage of taxis yesterday at Philadelphia International Airport and only brief rush-hour delays at Amtrak's 30th Street Station.

All 1,200 members of the Taxi Workers Alliance will be back at 6 a.m. today, alliance president Ronald Blount announced yesterday during an afternoon rally in front of Parking Authority headquarters at 3101 Market St.

"We've made our point. We've proved that we can launch a two-day strike," Blount told reporters in front of about 25 supporters. "This system is not working. It's been almost a year now. How long are we supposed to be patient?"

A strike called by a New York City taxi drivers' group over city plans for a high-tech video-and-fare system thinned the ranks of yellow cabs on the streets yesterday, producing frustrating waits on corners, long lines at the airports and angry exchanges over an ad-hoc fare system.

Union leaders and city officials differed over the effectiveness of the walkout. The New York Taxi Workers Alliance, which called the strike, maintained that 90 percent of drivers were idle yesterday. But Mayor Michael R. Bloomberg said the figure was far lower.

Still, many would-be passengers spent more time with hands in the air, stuck in that eternal pose of big-city hopelessness. And at the airports, a five-minute wait for a cab stretched to half an hour at some terminals, with 25 people waiting in line, looking at their watches, wondering why they were suddenly going nowhere when the plane had been on time.

The city had introduced a zone-based fare structure during the planned two-day strike - the ride into Manhattan from Kennedy International Airport would be set at $45, for example - but according to anecdotes, at least, the plan seemed to sow more confusion than convenience. It permitted group rides, but some drivers were unaware of it and were uncertain how much to charge. That led to more than one instance of audible angry dialogue between passengers and drivers.

LONDON, Sept. 3 - London's subway network virtually shut down at the height of the rush hour on Monday evening when 2,300 maintenance workers walked off the job in what they said would be a three-day strike over pensions and security.

Transportation officials then closed nine subway lines, the bulk of the system. They said it was too dangerous to keep the network going without the workers, who are responsible for maintaining and repairing tracks, signals, trains and the like. Just three lines - the Jubilee, Northern and Piccadilly lines, which are maintained by workers who belong to another union - were operating Monday night.

Commuters across London left work early in a rush to make it home before 6 p.m., when the strike began. Commuters arriving later found that their stations were locked or - in those stations still operating - that signs had been put up explaining that most of the lines had stopped operating.

Transport for London, the local agency that runs the subway system, predicted that the strike would cause "massive disruptions for millions of Londoners" and urged passengers to seek "alternative routes" - a difficult proposition in a city as large, sprawling and choked with road traffic as London.

The maintenance workers say that if their demands are not met, they will remain off work for three days, and strike again for another three-day stretch next week.

Adding to the general feeling of annoyance, the mayor, Ken Livingstone, said motorists driving into central London during business hours would still have to pay the congestion charge of 8 pounds a day, or more than $16, during the strike.