POTENTIAL CONFLICTS

Speed tables do not always work in certain locations. They should never be installed on a sharp curve, coordination between operators of emergency services and public transit should be done, drainage problems might occur due to the installation of them depending on the location, they can increase noise from trucks, and they can be expensive to maintain.

To learn more about raised crosswalks and possible conflicts, click here.

A short report, Do Speed Tables Improve Safety?, by W. Martin Bretherton Jr., P.E., illustrates a study from 2003 which observed 43 speed tables installed in 1994 and 1995 in Gwinnett County, Georgia. The data collected analyzed crash data from two years before and after the 1994 installations and three years before and after the 1995 installations. Although the study did not look at crash rates, it was concluded that crashes tend to be irregular making it hard to determine if speed tables actually helped decrease crash rates or increased the chances of them happening.

Cost

Low-cost

Speed bumps and speed tables cost on average $2,500 (ranging from $1,000 to $6,900 depending on size, materials, design, and drainage conditions).

Case Study National

A neighborhood in Naples, Florida was experiencing a high use of their residential roads and speeding. Located near the coast, Seventh Avenue traditionally experienced high traffic and speeding because of people who used their neighborhood as a cut-through to get to the beach. Before any measures were taken to reduce speed, average driver speed was 33 mph and they had approximately 8,000 vehicles through per day. The residents of 7th Ave. went to the City, a traffic study was conducted, and applied multiple strategies to slow traffic including medians, landscaping, and a speed table. After the improvements, another study was done which determined that the traffic count reduced from 8,000 to 5,000 vehicles per day and average speed dropped from 33 mph to 22 mph.