Dickson County Tightens Traffic Study Rules as Development Continues

Charlotte, TN — New commercial projects and subdivisions in Dickson County will face greater scrutiny over their potential impact on local roads after the County Commission approved significantly expanded requirements for traffic impact studies.

The Dickson County Commission approved amendments to the county's zoning resolution during its Sept. 21 meeting that lower the thresholds for requiring a traffic impact study.

Under the previous standards, triggers included a 50,000-square-foot development, a subdivision containing 50 lots, a planned unit development or a project expected to generate 150 new vehicle trips per day.

The new standards broaden those requirements considerably.

Any commercial or industrial development can now trigger a traffic impact study, while the threshold for subdivisions drops from 50 lots to 10. Planned unit developments will continue to fall under the traffic study requirements.

County officials said the changes grew out of concerns from the Dickson County Planning Commission that the existing rules did not always capture developments capable of producing significant traffic.

"The planning commission, I'll say this candidly, was becoming frustrated about certain developments not being subject to a traffic impact study," county attorney Andrew Mills told commissioners.

One problem was using the physical size of a development to determine whether a study was necessary.

Mills pointed to a drive-through coffee shop as an example. Such a business might occupy only 1,000 or 2,000 square feet — nowhere close to the previous 50,000-square-foot threshold — while potentially generating substantial vehicle traffic throughout the day.

The changes give county planning officials an opportunity to evaluate those traffic impacts before development occurs.

The amendments could also shift some of the financial burden associated with reviewing development away from county taxpayers.

If the Planning Commission determines that an engineer should independently review the findings of a developer's traffic impact study, the cost of that review will be paid by the applicant rather than Dickson County.

Later in the discussion, Commissioner O'Shea asked whether developers could also be responsible for improvements to county roads if a traffic study determines that a project will create additional needs.

Mills said that would depend on the findings of the traffic impact study.

Potential improvements could include turn lanes, deceleration lanes, improvements to development entrances or work along the portion of a county road bordering the property.

That, Mills explained, is one reason the Planning Commission has focused on when traffic studies should be required — allowing officials to determine whether existing roads can handle the additional traffic associated with a proposed development and, if not, what improvements should be made.

The traffic study requirements were part of a larger package of zoning amendments considered by commissioners.

The commission also approved new access-management standards for subdivisions. Developments containing 30 dwelling units or fewer can generally have one access point, while subdivisions with 31 or more require two. Developments reaching 151 units require three access points.

That portion of the proposal generated considerable discussion among commissioners over whether requiring two entrances beginning at 31 homes could create unintended traffic problems.

Commissioners questioned whether multiple entrances located relatively close together could increase the number of vehicles stopping and turning along county roads.

Officials said the competing concern is emergency access. A subdivision containing dozens of homes with only one entrance could become difficult for emergency responders to access if a crash or another incident blocks its only way in or out.

The county's new standards also interact differently with state highways. Officials explained that the Tennessee Department of Transportation ultimately controls access to state routes. If TDOT allows only one entrance onto a state highway, the county would follow the state's determination.

The changes come as county planning officials continue examining how Dickson County's development regulations should respond to growth.

Rather than waiting until a project reaches 50 lots or tens of thousands of square feet before examining its effect on surrounding roads, the newly approved standards give the county the ability to consider traffic impacts much earlier in the development process.

For future developers, that could mean more traffic studies — and potentially more responsibility for addressing the impact their projects place on Dickson County roads.