Traffic Impact Study

Reeves Creek is a proposed 465 acre mixed use development in Stockbridge. The project is anchored by a proposed county-owned convention center and 10,000 seat arena, but also includes over 1,700 residential units, commercial space, office buildings, and a mass transit station. The majority of the land is located within unincorporated Henry County, with small portions in the city of Stockbridge and unincorporated Clayton County.

The traffic impact study for the project was completed in August 2019 by Lowe Engineers of Atlanta, GA. The full traffic impact study (2,470 pages) is available to view through the ARC website; a summary of its recommendations has been compiled below.

Study Area

The Georgia Regional Transportation Transportation Authority (GRTA) identified 34 intersections and 28 roadway segments for inclusion within the traffic impact study. GRTA requires the applicant to evaluate these locations based on their existing present-day status, calculate future background growth through the project’s build out (year 2035), then factor in the estimated trip generation to identify future roadway needs.

Net Trip Generation

Trip generation for the proposed project was created using the Institute of Traffic Engineers (ITE) Trip Generation Manual 10th Edition, 2017. Reductions were credited for internal capture, modal split, and pass-by trips. A copy of the trip generation has been copied below. Values are in daily vehicle trips.

TotalInOut
Total Trips56,37728,19328,184
Reductions for Internal Capture12,2296,1156,114
Reductions for Modal Split1,051529522
Reductions for Pass-By Trips5,8442,9582,886
Total Net New Project Trips37,25318,59118,662

Recommended Improvements

The traffic impact study recommends widening projects in two phases, year 2029 and year 2035, based on the development’s expected timeline for development. Out of the twenty eight roadway segments evaluated in the study, twenty one will require some form of widening to support either natural background growth or the new development over the next fifteen years.

The most significant of these projects include the following:

  • Widening SR 138 / Lake Spivey Parkway between Mt Zion Pkwy / Speer Road and Davidson Pkwy to six travel lanes by year 2035, with the exception of providing only a third eastbound travel lane within the I-75 interchange. This project would include interchange expansion work at I-75 exit 228 and I-675 exit 1. Although not mentioned in the report, the conversion of these interchanges into diverging diamond interchanges (DDI) or single-point urban interchanges (SPUI) would be beneficial.
  • Widening US 23 / SR 42 / SR 138 / North Henry Blvd between SR 138 and Flippen Road to six travel lanes, and between Flippen Road and US 23 / SR 42 to include a third eastbound travel lane, by year 2035.
  • Widening Flippen Road between US 23 / SR 42 / SR 138 / N Henry Blvd and Banks Rd to four travel lanes by year 2035. Although the traffic impact study did not study Flippen Road south of Banks Road, widening work is likely to be required further south to Hudson Bridge Road.

In addition to roadway widening projects, the traffic study recommends intersection improvement projects at twenty seven of the thirty four study intersections. These improvements focus on the addition of turn lanes, through lanes, traffic signals, or alternative intersection designs (restricted crossing U-turn’s, etc).

Proposed Interstate 75 Access

The development is proposing a new Interstate 75 access point at Walt Stephens Road / mile 226. The proposal would include northbound ingress and egress only with no changes to southbound travel lanes. The traffic impact study states that obtaining the approval of the Federal Highway Administration (FHWA) is a lengthy process, one that requires the completion of an interchange justification report, and that “it is unknown if FHWA would approve…an interchange serving only one direction of travel.”

Commentary by Georgia DOT about the proposed interchange and the project as a whole is included within the ongoing development of regional impact (DRI) review process. It is unlikely that GDOT will support pursuing the interchange given the proximity of Walt Stephens Road to I-675 and that such an interchange would exceed the preferred average spacing for interchanges within an urban area. The average spacing has heightened significance in close proximity to system-to-system interchanges, such as the case here, where two interstates interconnect.

Estimated Cost of Improvements

Moving Henry Forward has calculated an estimated cost to complete the recommended improvements. This is not included within the traffic impact study but rather extrapolates the study into a financial figure. The estimate is based on average project costs in the present-day. This estimate does not consider future inflation nor any factors that may increase cost (property condemnation, bridge work, etc) and should be considered a rough estimate only.

RecommendationCost per UnitEstimated Cost
Roadway Widening17.61 Lane Miles$4 million per lane mile$70,451,000
Turn Lane Additions76 new turn lanes$0.5 million per turn lane$38,000,000
Total Estimate$108,451,000

Note: the cost estimate does not include the proposed Interstate 75 access at Walt Stephens Road, the cost of internal roadways to be constructed within the project site, nor roadway widening projects that are already programmed (US 23 / SR 42 between SR 138 and I-675 & Rock Quarry Road).

Last updated on September 16, 2019

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