August 21, 2026

By Mary Beth Gahan

If Cottonwood, a proposed development off Dixon Lane, is approved by town council this fall, the first Costco customers could be pulling into the parking lot in May 2028. By 2031, the entire 86-acre development would be built out in a part of town where congestion already occurs daily.

A 400-page traffic impact analysis that was recently completed for the project details how well the surrounding roads would be able to accommodate the increase in traffic, as well as what improvements are recommended if the development moves forward.

Cottonwood would be a boost for the town’s sales tax revenue, but residents have expressed concern on social media and in emails about what that means for drivers in the area. The site is next to Marcus High School’s athletic fields, across the street from Watermere at Flower Mound, a retirement community, and down the street from Marcus High School.

“Of course the roads and traffic lights can handle it — they're inanimate objects. The humans are the ones who need to decide whether the tradeoff is worth it to them,” Planning and Zoning Commissioner Michelle Jackson said.

One sticking point yet to be hashed out is the option for a traffic signal or two-lane roundabout at the intersection of Dixon Lane and Whyburn Drive. A roundabout passes capacity tests with flying colors and would cost the taxpayers less to maintain, making it a must-do for some town leaders. But right-of-way issues could mean moving the intersection slightly. It’s not clear who would foot the bill.

The development is still under review by town staff and will require approval from town council after a public hearing in the coming months.

The traffic impact analysis was paid for by the applicant and the town commissioned Kimley-Horn and Associates Inc. It looked at peak weekday a.m. and p.m. traffic and determined the level of service — a grade ranging from A to F given to the road based on traffic flow.

It took into account TXDOT buildouts of FM 2499 and FM 407, which are both state roads, as well as the planned extension of Whyburn Drive from Dixon Lane to FM 407.

Phase I of Cottonwood would include restaurants, a gym, Costco, and 222,000 square feet of warehouse space. That would be built by 2028, according to the traffic impact analysis. Phase II, which would be completed by 2031, would include the rest of the development: the bulk of the planned restaurants, shops, a bank, and 30,000 square feet of warehouse space.

When completed, there would be three spots for cars to pull into Cottonwood from Dixon Lane. Along Whyburn Drive, there will be six.

On average, 1,133 additional cars would come in and out of the development during the a.m. peak period by the time it is built out. During the p.m. peak, the number rises to 1,345. Fast food restaurants and Costco would be the main drivers of traffic, the report said.

The current master thoroughfare plan has an extension of Whyburn Drive stretching north from Dixon Lane to FM 407 as a two-lane urban collector road. Another option is to make it a four-lane undivided urban minor arterial road, and a representative for the developer expressed a desire to pay for that upgrade.

The analysis shows that a two-lane road’s capacity rating would be at .93, or “tolerable” by 2036 during the p.m. peak. Anything over 1 is failing. A four-lane road would change it to .38, or “acceptable.”

Westbound Dixon Lane between FM 2499 and Whyburn Drive would be another congested spot during the p.m. peak by 2036, with a rating of .89.

“People making decisions have to consider the human aspects which are not quantifiable: frustration due to increased commute times, the suburban mama barely making it to school on time who is now facing another traffic stop, and the undeniable fact that increasing the volume of traffic is directly correlated with increasing the occurrence of fender-benders,” commissioner Jackson said.

There are several intersections that would need to be improved if the development moves forward, especially to accommodate the afternoon rush. All but one of them would be paid for by the developer.

The intersection of FM 407 and FM 2499, which is under construction by TXDOT, currently has a level of service of “F” for east and westbound traffic during p.m. peak hours. It is projected to be classified as an “E” by 2036, according to the report.

At Dixon Lane and FM 2499, which is currently a “C”, the level of service is expected to drop to an “E” for a.m and p.m. peak hours by 2036 if no changes are made to the roadway. The traffic impact analysis recommends adding another westbound turn lane and a dedicated eastbound right turn lane to bring the level of service to an “acceptable overall LOS,” the report said. The right turn lane would be the only improvement paid for by the town.

The intersection of Dixon Lane and Whyburn Road is still up for debate as to how it’ll look.

The town could build a traffic signal or a roundabout, which would be two lanes and 200 feet wide, making it larger than the ones on Chinn Chapel at Dixon Lane and Waketon Road.

According to the analysis, a traffic signal would put the northbound and southbound parts of the intersection at a level of service of “C” in the a.m. and p.m. peak periods starting in 2028. Overall, the intersection would have a level of service of “B.”

A roundabout at Dixon Lane and Whyburn Drive would have a level of service of “A” across the board.

At least two planning and zoning commissioners said at the Cottonwood work session that they’d like to pursue the roundabout option because it would increase traffic flow and cost less to maintain.

Mayor Pro Tem Adam Schiestel said he would like to tie the approval of the development to the guarantee that a roundabout will be put in.

“I like the idea of it being a traffic calming measure because everybody who hits this roundabout has to slow down in order to navigate it, it kind of discourages trucks and insulates the residential, high school area from the commercial area,” Schiestel said.

Randi Rivera with McAdams, the engineering firm working with Cottonwood Development Partners, said at the work session that the roundabout would likely end up costing more money to construct because of a need to shift infrastructure and move the intersection to the northwest slightly.

Melissa Demmitt, communications director for the town, said it is possible to place a roundabout at that intersection, but it would require right-of-way from nearby property owners, like Lewisville ISD, because the 200-foot-wide concrete circle would take up more space than a traffic signal.

If the roundabout is moved the northwest, it would be on the developer’s land and would not require the purchase of right-of-way. There is a building with a restaurant and retail planned at that corner, according to the site plan. It’s not clear how far the roundabout would cut into the development.

The cost of the roundabout or traffic signal, whichever is chosen, would be decided at the time of final engineering, Demmitt said.