The proposed project consists of the construction of a diamond interchange at Interstate 85 (I-85) and State Route 324 (SR 324). The proposed interchange is in northern Gwinnett County, and is situated approximately 2.7 miles northeast of the I-85/SR 20 (Buford Drive) interchange (Exit 115) and approximately 1.9 miles southwest of the I-85/Hamilton Mill Road interchange (Exit 120). The project would include a northbound deceleration lane of approximately 1,500 feet on I-85 to facilitate a two-lane exit to SR 324 and an acceleration lane of approximately 1,200 feet to provide a parallel two-lane southbound entrance to I-85 from SR 324. The north facing ramps would have single-lane junctions with I-85. The off-ramp approaches to SR 324 would consist of two left-tum lanes and one right-turn lane.
The bridge and roadway of SR 324 (Gravel Springs Road) would be restriped to provide two westbound left-tum lanes and one eastbound left-tum lane. Right-tum lanes would be constructed on
SR 324 at the approaches to the interchange on-ramps. Curb and gutter with sidewalks would be provided on SR 324 to match the existing typical section. Limited access rights would be acquired along SR 324 on each side of the interchange from Camp Branch Road to Morgan Road to implement access management. The overall project length is estimated at 2.32 miles, which includes 1.82 miles along I-85 and 0.5 mile along SR 324/Gravel Springs Road (Figures 1-9).
The original archaeological survey covered the concept phase of the proposed project, which only depicted the interchange ramps for approximately 1, 700 feet east of SR 324 and 1,500 feet west of SR 324 along I-85. Since then, final design depicts a northbound deceleration lane of approximately 1,500 feet on I-85 to facilitate a two-lane exit to SR 324 and an acceleration lane of approximately 1,200 feet to provide a parallel two-lane southbound entrance to I-85 from SR 324. In addition, SR 324 APE is depicted 470 feet north of the interchange and 600 feet south of the interchange to allow for restriping two westbound left-tum lanes and one eastbound left-tum lane and construction right turn lanes on SR 324 at the approaches to the interchange on-ramps. Limited access is also depicted along SR 324 on each side of the interchange from Camp Branch Road to Morgan Road to implement access management.
In addition, an overhead sign will be added to an existing overhead sign structure 2.43 mile south of the APE. The proposed signage installation would not require additional ground disturbance and is needed to signal the exit to SR 324 from the high occupancy toll lane (see Figure 2).
The APE for the proposed project would include the areas within the existing and proposed ROW. The existing right-of-way (ROW) width on SR 324 is 120 feet, and the existing ROW width on 1-85 is 300 feet. The project would be constructed on variable width ROW. The proposed ROW width on SR 324 would vary from 120 to 140 feet and would vary between 300 and 1,200 feet on 1-85. An overhead sign will be added to an existing overhead sign structure 2.43 mile south of the APE.
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