Comparison of Methods to Reduce Sidewalk Damage from Tree Roots

Tree roots growing under sidewalks are known to crack or lift pavement often creating a tripping hazard for pedestrians. This experiment was conducted to determine the long-term effects of below- and alongside-pavement treatments on tree root development and sidewalk damage. London, U.K. plane trees (Platanus × acerifolia) were planted next to sidewalks at the Bartlett Tree Research Laboratory in Charlotte, North Carolina, U.S., in 1996. Treatments installed at the time of planting were: DeepRoot Universal Tree Root Barrier (UB18-2), vertical polyethylene sheet, gravel, Foamular® 150 extruded polystyrene, and a structural soil. The sidewalks and soil beneath them were removed in 2006. Minimal sidewalk lifting or cracking was associated with the DeepRoot barrier, gravel, and foam treatments. Vertical root barriers and foam resulted in fewer and deeper roots under the pavement. Treatments had no impact on tree diameter growth.