CARRBORO - The Board of Aldermen has delayed consideration of the Shelton Station project until November because of concerns about how it could affect the balance of residential and commercial development downtown.

The board is weighing whether to rezone roughly 2.5 acres at 500 N. Greensboro St. from both general business and corporate town use to only general business. That change would require expanding the general business definition to permit denser housing and setting the conditions under which such projects would be allowed.

If approved, the rezoning would allow Shelton Station developers to draft more detailed plans.

The N.C. Department of Transportation, which maintains Greensboro Street, still must approve changes to preserve roughly the same level of traffic service while adding turn lanes on both sides of the street and rebuilding bike lanes, planting strips and sidewalks. The project's main entrance would intersect Shelton Street.

Town leaders remain concerned about the limited commercial space, although the developer increased it from 12,000 square feet to roughly 24,000 square feet, or 19 percent of the 126,000-square-foot project. The aldermen want at least 25 percent commercial.

Alderwoman Jacquie Gist argued at a recent board meeting that residential space is easier to sell in the current economic climate but that allowing more high-density residential downtown might have unintended consequences, like reversing long-term efforts to build the town's commercial tax base.

"Carrboro's long-term future cannot be determined by the current economy," Gist said. "If the board chooses to go in this direction, it will start Carrboro on a fast and slippery slope ... and we will be left with a downtown full of high-density, up to five-story, most likely, predominantly student apartment buildings with little or no non-residential to offset the tax base."

Alderman Dan Coleman countered that the change could create a "reasonable tool" in future high-residential density proposals.

Mayor Mark Chilton, while noting some reservations, noted the lack of public opposition to the project and said the town's public transportation corridors are the "reasonable and logical place for this type of zoning."

Shelton Station developer Ken Reiter, of Durham's Belmont Sayre LLC, said the revised plan meets the board's concerns by cutting residential units from 114 to 102 and adding a second floor of commercial space. The new plan also prices 10 percent of the units at 60 percent of the area median income - roughly $41,000 for a family of four - instead of selling 20 percent of the units at 80 percent to 100 percent of the area median income, or about $55,000 for a family of four.

The remaining units would be sold at market rate, Reiter said, and all the units would be marketed specifically to families and professionals.

Gist, meanwhile, balked at a condition that second-floor commercial space could revert to residential by Jan. 1 if interest is lacking.

"When you propose that ... and you know what the commercial market is like right now, that made me think that you may just want to build residential," she said.

The board told town staff to rewrite the proposed ordinance change to specify a minimum commercial requirement and clarify the conditions for increased density at Shelton Station and similar projects. The board will take the issue up again Nov. 15.