A series of bumps along the Williamsburg Bridge bike path has caused scores of crashes and must be removed, transportation advocates say.Nearly one in four cyclists and pedestrians has crashed or tripped and fallen because of the bumps, according to a survey by Transportation Alternatives.Attorney Adam White said he has filed two lawsuits against the city over the issue and has started proceedings to file as many as three more."I believe my five cases are the tip of the iceberg," White said. "It's like a war zone, the number of people who have crashed."Noah Budnick, projects director for Transportation Alternatives, said the injuries reported have been severe."People have dislocated their collarbones and fractured their ribs, jaws, noses and cheekbones," Budnick said. "This is not a very safe design. We're appealing to the city to remove the bumps."The 26 bumps in question are found on the Manhattan side of the bridge on the new combined bike and pedestrian pathway that opened two years ago. The 2-inch bumps are metal covers over expansion joints along the path."The bumps create a blatantly dangerous condition that people have complained about for two years and the city has done nothing about," Budnick said.A Transportation Department spokeswoman said the joints are a necessary part of the bridge that allow it to expand and contract during temperature changes, and cannot be eliminated.Transportation Alternatives questioned about 250 cyclists and pedestrians crossing the bridge last fall and summer for the study. Nearly two-thirds reported losing control of their bikes or tripping because of the bumps, while nearly 75% said their bikes were damaged as a result of the bumps.Ren? Ortiz, 32, a real estate broker in Williamsburg who regularly rides across the bridge, said he saw a cyclist crash because of a bump."It's scary. It's a hazard," he said, adding he tries to pop his front tire up before he hits each one because he is afraid of a blowout. "You're coming down fast and when you hit a bump, you can lose control."The city has done what it can to alert riders to the bumps by placing warning signs and painting them bright yellow, said Transportation Department spokeswoman Kay Sarlin.She said Transportation Alternatives should urge cyclists to slow down as they ride over the bumps.That is little consolation to Natalie Tyler, 29, a sculptor who is one of White's clients. She is suing the city over injuries she suffered in October while biking home from work."I had gone over six or seven of the bumps but then I hit one and my front wheel came off," said Tyler, who despite wearing a helmet fractured her left eye socket and nose in the crash.