TRAFFIC ENGINEERING AND TRAFFIC CALMING

Knox County maintains over 2,000 miles of roadway, over 80 traffic signals, miles of pavement markings, and lots of road signs. The traffic control devices (signs, signals and pavement markings) help to keep traffic moving on the road, and traffic engineering supports that goal. Here are some specific activities our department does:

• Update traffic signal timing- Some traffic signals operate in communication with nearby signals to progress vehicles along a roadway. Coordinated corridors include Maynardville Pike, Clinton Highway, Cedar Bluff Road, Dutchtown Road near Pellissippi Parkway, Hardin Valley Road near Pellissippi Parkway, Middlebrook Pike through Ball Camp, and Ebenezer Road. Other traffic signals are relatively isolated and operate independently. We update traffic signal timing, especially in the busiest corridors, every few years so that the timing matches the traffic volumes on the roadway. Isolated signals are updated less frequently, but timing at these is also based on the competing volumes of traffic entering the intersection.
• Maintain sign and pavement marking conditions- It can be frightening to drive on a rainy night when one hardly can see the pavement markings on the road. Signs that have weathered or that have been vandalized or otherwise are damaged or missing are of little value to drivers. Knox County monitors sign and pavement marking conditions and performs maintenance as needed to provide navigational guidance to drivers.
• Monitor safety performance- If there is a particular hazard along a roadway, the crash history will often make that known and give guidance to alternative treatments to address safety deficiencies. One example is the installation of roundabouts at some intersections. Most of these had shown relatively frequent crashes. Typical options depending upon the sites may include implementing all-way STOP control, installing a traffic signal, beefing up warning signs, and the like. Roundabouts have been a huge success in eliminating angle-type crashes with minimal delay to motorists. We periodically review crash data around the County to identify locations in need of attention. We also investigate specific safety concerns brought to our attention, and one of the first steps in these cases is to assemble the crash data to look for trends or patterns.

We administer a traffic calming program to address speeding concerns in residential neighborhoods. This program has been in place since 2000 and is similar to that of numerous communities around the nation. Our “work horse” in existing neighborhoods is the speed hump, a vertical deflection 14 feet in length parallel to the roadway centerline and three inches high at the middle. Speed humps can be placed in existing right-of-way at minimal cost to the County budget, and they are effective in helping drivers to change their behavior.

In conjunction with Knox County’s Codes Administration and Enforcement Office, we conduct reviews of driveway locations for new construction. Occasionally one will buy a home only to realize that they have very limited visibility when trying to pull into or out of their driveway. The addition of a driveway review step helps to address this condition early in the process.