It's not the way a mother wants to celebrate a son's birthday. Edward Heredia would have turned 4 years old on July 28.But instead of lighting birthday candles, his mother, Jazmine Heredia, 29, attended a somber ceremony on Thursday to mark the installation of new traffic lights at Fifth Ave. and 55th St., where the boy was killed by a pickup truck in February."Other kids can be safe," said a tearful Heredia during her first visit to the corner since her son's death. "It's hard. I'm not going to get him back."The new lights are just one of several measures to make the busy commercial thoroughfare safer for pedestrians.Fifth Ave. is not the most deadly for pedestrians in Brooklyn, but according to data compiled by the advocacy group Transportation Alternatives, five pedestrians were hurt at the same corner from 1995 to 2005.Ten or more pedestrians were injured at the nearby corners of 45th, 46th, 49th and 60th Sts. during that period. And a pedestrian was killed at 60th St.Lots of street traffic and pedestrians come to Fifth Ave. because of the shops, said Jeremy Laufer, district manager of Community Board 7. "There are a lot of conflicts between the two," he said. Henry Irving, 64, who lives just a few doors down from the corner where Edward was killed, said he was reminded of his own 3-year-old grandson when he saw the boy lying in the street that day last winter."I see his little foot hanging there," he said last week, standing on the corner.He gathered 300 signatures to make sure the city replaced the stop signs at 55th St. with a traffic light."This light will be a prevention effort forever," said Councilwoman Sara Gonzalez (D-Sunset Park).Local leaders with the Sunset Park Business Improvement District have asked the city to provide additional safety measures along Fifth Ave. when the sewer mains are repaired in two years.Specifically, they asked the sidewalks to be enlarged at corners to limit how far pedestrians have to walk to cross the avenue. The city Transportation Department has confirmed that "neckdowns" will be part of the plan."It'll be safer for the community," said Ike Shauli, the former president of the BID and owner of the store Party Party. "It protects the car from hitting the pedestrian."