North Charleston has only one speed hump on its city streets, but a project being considered this week would put two in each City Council district, for a total of 20 units citywide.

The devices being considered are called speed "cushions" -- not the more widely used slang term of speed humps -- because they are made of rubber and can be picked up, moved and relocated to a different site as traffic control and police requirements change.

Ray Anderson, assistant to Mayor Keith Summey, said there are several reasons why North Charleston has been reluctant to put in speed humps, ranging from the cost, need for emergency vehicle access, and the mix of county and state roads that crisscross the city's jurisdiction.

Traffic, however, in some areas of the city has increased to the point that extra control devices are being explored before areas get even more out of control. "You can't have a police officer in every street," he said.

The device the city is looking at is a unit manufactured by Traffic Logix.

It is installed as three small speed mounds that cross a section of the road.

The three sections are placed in the road close enough so that regular cars have to slow down as they pass over the raised rubber parts, while the divide between the three parts is wide enough so that the axles of emergency vehicles can pass through without slowing down. The cost of each device is about $3,000.

Purchasing the units will be considered by a City Council committee on Thursday.

City Councilman Ed Astle, who three years ago got the city to put up its first and only speed hump, on Wildflower Way in the Wescott Plantation neighborhood, said there is a need for the devices. The city's traffic patterns have grown significantly in recent years, he said, with some previously quiet local roads turned into speedy cut-throughs, or shortcuts to beat traffic lights or other points of congestion, he said.

"It's a safety issue and it's a way of controlling the traffic," he said.

Reach Schuyler Kropf at 937-5551 or skropf@postandcourier.com.