DEARBORN, Mich. (AP) - Wavy sidewalks in a Detroit suburb aren't a mistake -- they're purposely engineered to comply with the Americans with Disabilities Act. The Detroit Free Press reports that the sidewalks in Dearborn peak between houses and slope back down at the driveway level. The ADA requires sidewalks have a mild slope so people with limited mobility can move safely. The sidewalk must also remain above street level to allow for drainage, but driveways must be low enough to the ground for cars. The sidewalk changes come as the city upgrades its sewage system with new water lines and reconstructed roads. Public Works Director Jim Murray says modern cities have more space between houses and wider boulevards so the sidewalk slopes aren't as noticeable. He says many of Dearborn's streets were built before 1940 so they're not very wide. --- Information from: Detroit Free Press, http://www.freep.com