If you were walking along the 700 block of South Gay Street or the 2100 block of Cumberland Avenue last week, you may have noticed some curious-looking black box-like structures being installed below ground level.

These structures are new cutting-edge tree root boxes, and they'll help promote healthier urban trees with well-established deep root systems.

The hundreds of underground root boxes, or structural frames - a trademark product named Silva Cells - are being installed as part of a complete $1.5 million rebuild of the infrastructure in the 700 block of South Gay Street between Cumberland and Church avenues, as well as along Cumberland Avenue, which is undergoing a $17 million reconstruction.

For those who admire and enjoy shady tree-lined urban streets, the Silva Cells represent a significant improvement over traditional planting methods.

Silva Cells provide greater soil volume. They support the weight of the overhead sidewalk and reduce the need to compact the soil to support the sidewalk, which helps the tree roots. The Silva Cells also maximize the quality and amount of available soil, and they encourage the roots to grow downward, discouraging upward buckling of the sidewalks.


Silva cells also are being installed on the north side of the 2100 block of Cumberland Avenue.