Takoma Park has had its ups and downs on the issue of speed humps.

Residents lobbied vigorously to have the speed-reducing mounds placed in their heavily traveled streets as a safety measure, while commuters griped about the nuisance and potential damage to cars.

Construction of speed humps on six Takoma Park streets was completed last week, but even as they were built, the bumps made waves: some are too high and need shaving down, city officials acknowledged. Some, built along federal Department of Transportation guidelines, are too small, and are ineffective at slowing speeding motorists, the officials noted.

But the rest, they said, are just right at 12 feet across, four inches high. "We're pretty excited about the humps," said Richard Robbins, director of the Department. "If you're going 10 miles per hour, you won't notice them. But if you're going 30 to 40, you're gonna."

The humps were designed to slow traffic in the historic section of Takoma Park, where tree-lined residential streets are used as commuter shortcuts. Robbins characterizes the humps as "silent police officers."

The results are predictable: Residents are pleased. "They say it's reduced traffic by 30 percent," Robbins said. But commuters grouse.

Taxi driver Milton Anderson, 45, who drives the streets every day, often in rush hour, thinks the speed humps are unnecessary. "They will ruin your suspension after a period of time; they'll affect the springs and shock absorbers," he said.

Reginald Hackley, 41, a 10-year resident of Takoma Park who drives Maple Avenue "just about every day," said he'll switch to Carroll Avenue or Piney Branch Avenue.

But Robbins maintains that, because of their design, these particular humps shouldn't crunch car axles or wear out springs. "They cause a strange . . . a different reaction," Robbins said. "I don't think it would damage the underside of a car. It's like crossing a railroad track fast: it gives you a tremendous jolt but the car rides a straight line."

Traffic engineers draw a sharp distinction between humps and bumps: a hump is flatter and longer, painted with stripes and, supposedly, more comfortable to ride over, while a bump is more abrupt, more often found in shopping center parking lots and usually painted yellow. In a much-cited study, bumps were proved hazardous to motorcycles, fire trucks, school buses and other vehicles with stiff suspensions.

Currently, seven speed humps break Maple Avenue into a hilly stop-and-go affair with a speed limit of 25 mph; the recommended speed over the humps--to be posted shortly--is 5 mph. Cedar Avenue will have six humps. Both streets are popular routes from Philadelphia and Flower avenues.

There were 11 accidents on Maple Avenue in the first half of this year, 19 last year, according to Takoma Park police. After monitoring the street with radar for 46 hours this year, police wrote 112 tickets for speeding and traffic violations and issued 56 warnings.

More humps are destined for Westmoreland, Walnut, Willow and Mississippi avenues and Anne Street. All are identified by "speed hump" signs and unmistakable white lines painted on the asphalt perpendicular to the rise.

Speed humps have been rarely used in this area. In the District, along 46th Street NW between Massachusetts Avenue and River Road NW, the track record for the humps is disappointing, District officials said. Chief of Traffic Operations Gary Wendt said, "The 46th Street program is basically a failure. People either take another street or go as fast as they went before."

Still, Takoma Park Mayor Sam Abbott likes to say his goal for the city is "a stop sign on every corner, a speed bump on every block." He's not trying to force commuters to change their routes, he says, only to slow them down.