Heading north on GA 400 past the Webb Bridge Road overpass, there is a stretch of about three-quarters of a mile where the shoulder opens up as a flex lane all the way to Exit 11 at Windward Parkway. Starting Dec. 13, 2026, that lane closes for good, according to a City of Alpharetta notice dated Oct. 15. Crews will take down the flex lane signs, strip off the striping and set a temporary concrete barrier wall where drivers used to pick up an extra lane in the afternoon.
This is the first permanent change Alpharetta drivers will see from the SR 400 Express Lanes project. The project's first visible construction in the city, early work on bus lanes, also began at Windward. Both point to the same place, because once the rebuild is finished, Windward Parkway is where Alpharetta gets the most from it.
Dec. 13: the shoulder at Exit 11 stops being a lane
The city's notice spells out how the northbound stretch will work after the closure:
- Four northbound travel lanes stay open.
- Drivers exiting at Windward Parkway still reach the two-lane Exit 11 ramp from the right lanes.
- Drivers continuing north should stay in the through lanes and keep going straight.
- A temporary concrete barrier wall runs along the old flex lane.
The lane count through the stretch holds at four. The difference is that the shoulder won't open as a lane anymore. The flex lane gave Windward-bound traffic extra room at busy hours. After Dec. 13, that traffic shares the right lanes with everyone else, and the shoulder becomes a work zone behind a wall. The city's advice is to plan ahead and allow extra travel time while construction continues along the corridor.
The bus lanes started at Windward, too
On Nov. 4, crews started early construction on the dedicated bus lanes for the future Windward Parkway Park & Ride, according to the SR 400 Express Lanes October 2026 newsletter from the Georgia Department of Transportation. That work was scheduled to close part of the southbound Dryden Road sidewalk between Morris Road and Lighthouse Lane from Nov. 4 through Nov. 13, with the northbound sidewalk open to pedestrians. The sidewalk closure had a fixed window. The bus lanes it made room for are the start of the Windward Parkway Park & Ride.
Along the full 16-mile project, the same newsletter says October work included tree clearing, soil grading, concrete barriers, lane striping and drainage, "all in preparation to begin constructing the outside lanes." Retaining wall construction has started in Segments B and C, and bridge work has begun at Union Hill in Segment C. The newsletter says current and upcoming work focuses on that outside widening, so most of the near-term activity happens along the edges of the highway and away from the center lanes.
What Windward and the rest of Alpharetta get in 2031
Design materials in GDOT's project executive summary describe three Alpharetta access points into the express lanes, and Windward Parkway is the one with both a direct connection and a transit hub.
| Location | Planned express-lane connection | Transit tie-in |
|---|---|---|
| Mansell Road | Direct connection to the express lanes | Bus rapid transit stop planned at North Point Mall |
| Old Milton Parkway and Haynes Bridge Road | Slip ramp linking the express lanes with both roads | MARTA lists a proposed Old Milton Parkway station |
| Windward Parkway | Direct express-lane access from Windward Parkway and the MARTA park-and-ride | Windward Park & Ride, the northern end of the planned bus service |
GDOT's project FAQ describes bus rapid transit service between North Springs and Windward, with direct stops at Holcomb Bridge Road, North Point Mall and the Windward Park & Ride. MARTA's GA400 corridor page shows four proposed stations north of North Springs: North Point Mall, Holcomb Bridge Road, Old Milton Parkway and Windward Parkway. MARTA notes that the Old Milton Parkway station is outside GDOT's express lanes project, and it lists the bus project's status as "Design." The Atlanta Journal-Constitution reported that the express lanes project will help pay for the two bus stations near Holcomb Bridge Road and North Point Mall.
Taken together, those plans make Windward the place where the highway, the park-and-ride and the bus line all meet. The Dec. 13 barrier and the Dryden Road bus-lane work are the first parts of that interchange you can actually see.
Between now and then, closures arrive in short windows
Before 2031 comes a long stretch of construction. The project officially kicked off on April 22, 2026, at an event on the roof of an Alpharetta parking garage overlooking GA 400. The AJC described it as an $11 billion public-private partnership that will rebuild the corridor over five years and add 16 miles of express lanes and a dedicated busway. The lanes will run from near the North Springs MARTA station to just past McFarland Parkway in Forsyth County. GDOT's FAQ says the lanes are expected to open to traffic in 2031. The project executive summary sets service commencement for Feb. 14, 2031, with final acceptance planned for Aug. 13, 2031.
So far, most of the disruption in Alpharetta has come as short lane closures posted a few days ahead. GDOT's Oct. 30 lane closure advisory shows what that looks like. Three of the Alpharetta-area closures it listed, all now past:
- Southbound GA 400, Haynes Bridge Road to Northridge Drive: one lane closed Nov. 2 through Nov. 6, 10 a.m. to 3 p.m.
- Mansell Road, Davis Drive to North Point Parkway: one lane closed Nov. 2 through Nov. 6, 10 a.m. to 4 p.m.
- Northbound GA 400, Old Milton Parkway to Windward Parkway: one lane closed Saturday and Sunday, Nov. 7 and 8, 7 a.m. to 7 p.m.
Each was scheduled for weekday midday or weekend daytime hours, and the advisory says schedules can change with weather and other factors. A July 23 city update also warned of overnight GA 400 lane closures, traffic shifts and less shoulder space as the work goes on. Because closures are posted on a rolling basis, the most reliable way to plan a commute is to follow the alerts as they're issued.
Old Milton Parkway has its own timeline, ending in 2029
There is a second, separate project on Old Milton Parkway, one of the roads that will connect to the new slip ramp. A City of Alpharetta update describes widening Old Milton Parkway between North Point Parkway and Kimball Bridge Road. Plans call for one more lane in each direction, new sidewalks, a raised median and replacement of two bridges over Big Creek, with completion expected in late summer 2029.
That puts the Old Milton work on a schedule that overlaps with the express lanes for most of the next three years. It is set to finish about a year and a half before the express lanes open.
The dates in order
- April 22, 2026: official construction kickoff in Alpharetta.
- Nov. 4–13, 2026: early bus-lane work for the Windward Parkway Park & Ride closed part of the southbound Dryden Road sidewalk.
- Dec. 13, 2026: the northbound flex lane from just south of Webb Bridge Road to Exit 11 closes permanently.
- Late summer 2029: expected completion of the Old Milton Parkway widening between North Point Parkway and Kimball Bridge Road.
- Feb. 14, 2031: scheduled express lanes service commencement.
- Aug. 13, 2031: planned final acceptance.
Where the alerts come from
GDOT's SR 400 Express Lanes project hub has a "Subscribe to Alerts" sign-up, an archive of past traffic alerts and the monthly newsletter. Questions go to the project hotline at 770-209-2520 or to [email protected]. For live conditions on a given morning, GDOT points drivers to 511ga.org, the 511 phone line or the Georgia 511 app.
Over the next five years, a home's distance to Exit 11, to the Mansell connection or to the Old Milton slip ramp may matter more than it used to. If you want to know how GA 400 access and construction timing apply to a particular street or property, Tina Sui and the TJS Team can go through it with you in English or Mandarin, by phone or on WeChat. Request a personalized market & investment consult.
