The speed tables in DeKalb, notably on Hillcrest Drive, were instituted to help reduce an area speeding problem.
The Hillcrest Drive tables were installed in August 1999 by DeKalb Traffic Engineering.
“Speeds were high; we wanted to lower them for the neighborhoods,” said Assistant City Engineer Joel Maurer.
Many of the residents who live directly off Hillcrest Drive had complained about cars driving too fast through the neighborhood. Residents were upset because they did not feel comfortable walking, running or having their children play outside with cars driving too fast.
The speed tables increasingly seen throughout the region are easier on cars and passengers than speed bumps. Speed tables have a rise of three to four inches. While bumps are rounded, the tables are flat on top, which gives cars more of a jolt when crossing. The tables are usually 22 feet long.
“The speed tables are a more flat area with a longer distance,” Maurer said. “The car doesn’t have to stop with that abruptness.”
The structures cost $2,500 to $6,000 each, depending on design and materials used.
Engineers are looking for other solutions to the speeding problem. One new device, the Dunlop Transcalm hump, is being tested in Britain. Much different than speed tables, the humps are filled with air and have speed-sensitive valves. When a car moving at a slow speed crosses the hump, the valve opens and releases air, causing deflation for a softer ride. When cars cross at high speeds, the valve remains closed, leaving the hump extremely hard.
Driving the speed limit is not only recommended as a consideration to residents, but also for the sake of one’s vehicle.
Going over the speed tables faster than 20 mph could result in serious damage to a car.
“It can affect your alignment, but the biggest reason to be careful is that it is hard on the suspension,” said Dana Doty, a mechanic at Archer Alignment, 424 1/2 E. Lincoln Highway. “Your suspension is safe at around 20 mph, but at 30 to 40 mph, expect damage.”
Doty said the tables are much better for cars than bumps. The damage resulting from driving too fast over the speed tables can range anywhere from $200 to $500, depending on the car.