Three people were struck and killed in separate traffic accidents across the city yesterday - the latest victims in a rising number of pedestrian deaths.Mario Sagastume, 47, of Suffolk County, L.I., was visiting his former neighborhood when he fell in the crosswalk of Ashford St. near Liberty Ave. in East New York, Brooklyn, police said.A beige Nissan Maxima hit Sagastume at 12:10 a.m. and sped off, cops said. He died about three hours later at Brookdale University Hospital."Every month or so, there's a major accident here," said Clemon Pyatt, 41, who lives nearby. "There should be a light here."At about 4 a.m., a 25-year-old man walking with a friend was hit by a van at Essex and Delancey Sts. on the lower East Side. The unidentified victim, who a police source said was visiting from Massachusetts, died at the scene. The driver was questioned by cops but not charged with a crime.Nine hours later, Alice Chow, 49, stumbled into the path of a school bus at 1 p.m. near Austin St. and Lefferts Blvd. in Kew Gardens, Queens. Chow had been walking with her mother, the police source said.Chow, of Flushing, died at Jamaica Hospital about an hour after she was hit. The bus was not carrying any children at the time.Last year, 163 pedestrians were killed in auto accidents across the city - up 4% compared with 2005, according to the Department of Transportation."The number is up and it's cause for concern," said Noah Budnick, a spokesman for Transportation Alternatives, a pedestrian advocacy group. "There should be zero people killed on city streets."Since 2000, the number of pedestrian fatalities in the city has fluctuated between 163 and 192 - an improvement over previous eras. In 1989, for instance, 377pedestrians died.Still, activists want the city to do more. Among their recommendations are speed bumps at crosswalks and changing the timing of traffic lights to give those on foot a head start over those behind the wheel.The loved ones of New Yorkers killed by cars are expected to gather at 3 p.m. today for a rally at City Hall.