After taking on smoking, trans fat and guns, Mayor Michael Bloomberg's next crusade should be to make streets safer for walking, pedestrian safety advocates charged yesterday.Dozens of relatives and friends who lost loved ones to motorists joined Transportation Alternatives to call on the mayor to institute changes they claim will eliminate 2,000 pedestrian injuries and fatalities by 2009, including additional crossing time and raised crosswalks. They also want the city to improve conditions along problematic roadways such as Hylan Boulevard on Staten Island, Flatbush Avenue in Brooklyn, Ninth Avenue in Manhattan, Roosevelt Avenue in Queens and Grand Concourse in the Bronx."This is a problem that the city must address," said Noah Budnick, a spokesman for the nonprofit group that claims 170 pedestrians were killed on city streets last year. "This is 2007, this is New York City, how can these streets be filled with such carnage?"They also called on city and state to form a task force to strengthen laws against motorists who kill or injure pedestrians.In a statement issued yesterday, the Dept. of Transportation said 156 people were killed in both 2004 and 2005, the lowest total since the city began tracking pedestrian deaths in 1910. Last year, 163 pedestrians were killed. The agency acknowledged, however, "in the wake of several tragic accidents, it is clear that more needs to be done."Police said three people were killed Saturday after being struck by motorists. Mario Sagastume, 47, of Long Island, died in a hit-and-run in Brooklyn. Alice Chow, 49, of Flushing, was killed by a yellow school bus along Lefferts Boulevard. Christopher Webber, 25, was struck by a van at Essex and Delancey streets, about a block from his home.Meanwhile, Rachel Myers, who attended yesterday's rally to honor her fiance who was killed in a hit-and-run crash in the Upper East Side, said the pain still lingers after three years."Experiencing the loss of a loved one on the streets of New York destroys families and it impacts people forever," she said. "And you're not going to read about that in the papers and you're not going to see that in the statistics. Part of the problem is we don't realize what a huge issue this is."