An infiltration approach to reducing pavement damage by street trees

Area of Science:

• Urban forestry
• Civil engineering
• Horticulture

Background:

• Street trees offer urban benefits but cause pavement damage due to shallow root growth.
• Conventional impermeable pavements exacerbate root-related infrastructure issues.

Purpose of the Study:

• To assess if permeable pavements with gravel layers reduce tree root damage to urban infrastructure.
• To evaluate the impact of different gravel basecourse depths on root growth and pavement integrity.

Main Methods:

• A six-year field experiment comparing tree root growth in conventional impermeable pavements versus permeable pavements with varying gravel depths.
• Monitoring of root system depth and tree height.

Main Results:

• Permeable pavements with underlying gravel layers successfully directed tree roots deeper into the subgrade.
• Deeper gravel basecourses showed a more pronounced effect in guiding root growth downwards.
• Tree height was not significantly affected by the permeable pavement systems after six years.

Conclusions:

• Permeable pavement systems with gravel basecourses are effective in mitigating street tree root damage to pavements.
• Gravel layer depth is a critical factor in directing root growth away from pavement structures.
• This approach offers a sustainable solution for integrating trees into high-density urban environments.