A tree in Sandy Springs that took root in the Great Depression will live to see an even riper old age.

The now massive water oak, on Abernathy Road, will be protected when a road expansion project begins this fall.

The state Department of Transportation has agreed to some design changes to help the tree survive, including moving the new sidewalk slightly and using a porous material for the road shoulder, a state spokesman said.

Both steps should help protect the 75-year-old tree by allowing more water and oxygen to reach its roots, said Michael Barnett, an arborist with the city of Sandy Springs. A fence will also be installed around the tree, to protect it from heavy construction equipment.

Of all the trees in the city, the oak on Abernathy has captured the most public attention this year. Part of its prominence is the location. About 22,000 commuters pass by it daily, many of them heading to or from east Cobb County to Ga. 400.

"It's worth saving," Barnett said. "It's unusual to get one that large."

A sister water oak, slightly smaller and to the west, also will be preserved. Signs soon will be installed along Abernathy, letting passers-by know, said Nina Cramer, president of Trees Sandy Springs, one of the community groups that's had a hand in saving the specimens.

The larger oak has a trunk, rippled with age, that measures 66 inches in diameter. Its canopy reaches over Abernathy and deep into its property. The smaller oak has a diameter of 38 inches, Cramer said.

Sandy Springs, which plans to build a park along the widened Abernathy, wants to make the two oaks a focal point.