If you buy a home in Alpharetta this fall, you will live through the SR 400 Express Lanes construction before you ever drive on the finished lanes. GDOT expects all planned construction on the 16-mile project to wrap up by 2031. That is about five years from now, which covers much of a typical ownership period. Crews are already working near several Alpharetta interchanges that a buyer will use on the first drive to a showing.
The bigger issue for a buyer is that nobody can yet say for certain how a particular Alpharetta address will connect to the new lanes. The latest GDOT roadway roll plot, dated June 29, 2026, is still labeled "PRELIMINARY PLAN." So the commute you are paying for depends on which exit is closest to the house. The headline promise of two new lanes in each direction does not tell you that.
You Own the Home During the Construction Years
GDOT said in March that construction would begin in early April 2026. By September, the department's monthly newsletter showed active work in all three segments of the corridor. The project is being delivered as a public-private partnership. The developer is SR 400 Peach Partners, LLC. It is responsible for design, construction, operations and maintenance during construction and for 50 years after the lanes are finished. USDOT lists Meridiam, ACS Infrastructure Development and Acciona Concesiones as equal owners of the partnership. Dragados and Acciona Construction are named as lead construction contractors.
GDOT has explained how it intends to manage the disruption. Kyle Collins, the GDOT P3 project manager, told Appen Media:
"No lane closures are planned to occur during major holidays or during designated high-traffic periods, and any necessary closures are coordinated to avoid significant disruptions."
Collins also said the lanes will be mostly at grade and will generally sit on the inside of the existing mainline lanes. Closures therefore tend to happen overnight and in small pieces rather than all at once. A buyer who only tours homes on weekday afternoons may never see the work that matters most to a future commute.
Alpharetta Is Split Between Two Construction Segments
GDOT divides the corridor into three segments, and Alpharetta falls in two of them. Segment B runs from Roberts Drive in Sandy Springs, across the Chattahoochee River and through Roswell, to Kimball Bridge Road in Alpharetta. Segment C runs from the center of Alpharetta north to Shiloh Road in southern Forsyth County. Homes a few miles apart can sit next to different stages of work on different schedules.
Here is what the most recent updates describe:
- Encore Parkway to Haynes Bridge Road. Crews were clearing brush along the shoulder in June. The September newsletter reported excavation and earthwork in this stretch.
- Windward Parkway MARTA Park & Ride. Grading and clearing were continuing near the lot in June. GDOT said the work was not expected to affect commuters who use it.
- McGinnis Ferry Road to McFarland Parkway. Drainage and earthwork are under way. GDOT said a northbound traffic shift was coming in the following weeks.
- Union Hill Road. Foundation work on a new bridge that will carry an express-lane on- and off-ramp was scheduled to start in October.
On this weekend's GDOT schedule, which runs October 2 through 5, overnight rolling right-lane closures are listed as drivers approach ramps at Mansell, Haynes Bridge Road, Old Milton Parkway, Windward Parkway and McFarland Parkway. GDOT posts that schedule weekly, so the list will change by next weekend.
The Access Map Is Still a Draft
Toll lanes only help you if you can get on and off them near home and near work. For Alpharetta, the plans have changed more than once.
SR 400 Peach Partners published an FAQ in 2023 that listed access points from the regular lanes south and north of Northridge Road, south of Haynes Bridge Road, and north of McFarland Parkway. It also listed new express-lane interchanges at the North Springs MARTA Station, Old Dogwood Road, Tradewinds Parkway and Union Hill Road. The FAQ added that "access points are subject to change based on final design." The developer's winning proposal later added a set of alternative technical concepts that included several ramps serving Alpharetta directly.
| Interchange | What has been proposed | What current sources confirm |
|---|---|---|
| Mansell Road | A slip ramp linking the express lanes to Mansell Road, in the developer's proposal | No published source confirms express-lane access here |
| Haynes Bridge Road / Old Milton Parkway | A slip ramp connecting the express lanes to both roads; the 2023 FAQ also lists access from the regular lanes south of Haynes Bridge | Not confirmed in the current published design |
| Windward Parkway / Park & Ride | Direct access from Windward Parkway and the MARTA lot, plus a northbound slip ramp from Windward | Appen Media published a GDOT rendering of a reconfigured Windward exit; direct car access is not confirmed |
| McGinnis Ferry Road | Braided ramps connecting directly to the express lanes | The express lanes drop from two to one in each direction here; the ramps are not confirmed |
| Union Hill Road | A new express-lane interchange in the 2023 FAQ | Confirmed; ramp-bridge foundations scheduled to start in October 2026 |
Of the interchanges a buyer might weigh, Union Hill Road, in Forsyth County, is the only one where a published 2026 GDOT source confirms an express-lane ramp. Every Alpharetta row in the table is still a proposal. If a listing description or a neighbor promises "express-lane access at our exit," ask where that came from. The GDOT drawings do not yet support it.
North of McGinnis Ferry, Express Capacity Drops by Half
GDOT's March 2026 FAQ sets the lane count at two express lanes in each direction from North Springs to McGinnis Ferry Road, then one in each direction from McGinnis Ferry to McFarland Parkway. McGinnis Ferry runs along the Fulton County line. That makes it the dividing line between full and reduced express capacity, right at Alpharetta's northern edge.
How the lanes are priced matters here too. Drivers pay with a Peach Pass, and the toll changes with traffic volume so the lanes keep moving. Registered transit buses and vanpools ride free. Freight vehicles and trailers are not allowed. The same pricing system will run over two lanes on one stretch and one lane on the next. The lanes promise a predictable trip time, not a fixed price.
Johns Creek's McGinnis Ferry Road widening is a separate project managed by the city. GDOT's FAQ expects it to finish in 2028. Buyers near that interchange should expect two construction schedules on the same road through at least 2028.
Two Transit Maps for One Corridor
MARTA's GA 400 bus rapid transit line is the other piece of the corridor's future, and the two agencies describe it differently. MARTA's project page lists proposed stations at North Point Mall, Holcomb Bridge Road, Old Milton Parkway and Windward Parkway. It says the Old Milton location falls outside GDOT's express-lanes project. GDOT's March 23, 2026 FAQ names only Holcomb Bridge Road, North Point Mall and the Windward Park & Ride as stops. MARTA lists the project's status as "Design" and gives no opening date for any station.
So the North Point and Windward stations appear on both lists, while Old Milton appears only on MARTA's. If a future transit stop near downtown Alpharetta matters to you, Old Milton is the station with the least certain timing.
A Commute Test for the Construction Years
Since the finished road is years away and its access points are not final, test the commute against the road as it is now:
- Drive the route at the hours you will actually commute, including at least one evening trip, because GDOT schedules lane closures for off-peak hours.
- Check the weekly GDOT closure schedule for the ramps near the property before a second showing.
- Use the project hub and monthly newsletter at 0001757-gdot.hub.arcgis.com to see which segment the home sits next to and what work is coming.
- Treat proposed ramps as unconfirmed until GDOT replaces the preliminary roll plot with a final plan.
- Ask about noise barriers by location. GDOT's 2023 environmental commitments found 27 of 30 evaluated barriers feasible and reasonable. It also said locations would be reevaluated before final design. The City of Alpharetta's February 23, 2026 meeting agenda included an SR 400 Express Lanes staff report and a noise barrier fact sheet.
FAQ
When will the GA 400 express lanes open through Alpharetta?
GDOT expects all planned construction to finish by 2031. It has not published a separate opening date for the Alpharetta section.
Will carpools ride the express lanes free?
No. The developer's FAQ says every motorist pays a toll no matter how many people are in the car. Registered transit vehicles and vanpools are exempt.
Is the Windward Parkway Park & Ride still usable during construction?
Yes. GDOT said in June that grading and clearing near the lot were not expected to affect commuters who park there.
If you are weighing homes along the GA 400 corridor and want to know how the construction schedule and the proposed access points line up with a specific address, Stovall Properties Group can help you test that commute before you write an offer. Call or text Sarah for a personalized market consultation.
