Public Works Director Tommy Sanders said the speed tables are a “traffic calming device” that can be used in areas where vehicles need to travel at posted speeds while still preventing speeding.
“It’s similar to a speed bump in that it slows down traffic. But what a speed table is designed to do, it’s designed so you can still go the posted speed limit safely over it, but not much faster. If you go much faster than the posted speed limit, it’s uncomfortable,” he said.
According to the Institute of Transportation Engineers’ website, a speed table typically takes up 22 feet of roadway, with 6-foot ramps on both sides of a 10-foot flat section. The most common heights are between 3 and 4 inches above the roadway. The ITE reports that speeds are reduced and collisions have been reduced by an average of 45 percent, though that percentage is not adjusted for traffic taking alternative routes. Any delays to emergency response, ITE reports, are less than 3 seconds per speed table.
The ordinance allowing for speed table installation is a new one, Sanders said.
“On public streets in Cartersville we don’t have any speed tables. In the past it’s just been our policy not to install them. But what passing this ordinance does is it gives the capability for the city to put them in in certain areas. We quite often have calls in residential areas, mostly subdivisions, about speeding complaints and people requesting speed bumps,” he said. “So now we can respond to those. We can tell them to submit a request to us in writing.”
The speed ramp, thanks to its 6-foot approach angles and wide middle section, is much gentler on vehicles than a speed bump when it comes to combating speeding. That reduced impact makes them appropriate for residential areas, Sanders explained.
“On a public street if we have a speed limit sign that says 25 mph, not only are you not supposed to go faster than that, but what that’s telling the public is it’s safe to travel 25 mph on that roadway. That’s the reason we can’t put speed bumps on the road because, if you went 25 mph over a speed bump, you’re going to do some damage to your car. That’s not very safe. That’s the reason we have to install speed tables to control the speed,” he said.
Once public works receives a written request it starts a process that includes a traffic study and a speed study. If the department concludes a speed table is necessary, Sanders said a notice will be put out identifying the area where a table may be installed. Fourteen days after the notice, a public meeting is held and community members have the opportunity to give the department feedback. The feedback is then compiled and the request is presented to the city council, which has final say on whether the speed table is installed.
“It’s not something that everybody goes hooray when you install them,” Sanders said. “That’s why the process is set up the way it is — to make sure there’s consensus. Well, first off to make sure it’s needed and there’s a consensus in the neighborhood that they’re wanted.”
Assistant City Manager Dan Porta said the process allowed residents some say in how traffic flow affects their neighborhood.
“Again, it gives an opportunity for the neighborhoods — if they’re interested and having issues with traffic volumes and speeds in their neighborhoods — it’s one way to control that if they’re interested in having it installed,” he said.
For more information on the speed tables or to file a request, call public works at 770-382-5602.