Can Street Trees Help Prevent Roads from Overheating?
As another summer of record-breaking temperatures impacts the UK and Ireland, the resilience of our urban infrastructure is once again under the spotlight.
Recent reports highlighted councils deploying gritting lorries during heatwaves—not to combat ice, but to spread sand across roads where asphalt had softened under extreme surface temperatures (Read article HERE).
As dark road surfaces absorb solar radiation, temperatures can exceed 50–60°C, causing bitumen within the asphalt to soften and increasing the risk of rutting, deformation and surface damage.
While emergency maintenance can help protect road surfaces during periods of extreme heat, there is another, longer-term solution that often goes overlooked: urban trees.
Street trees do far more than improve the appearance of our towns and cities. They function as natural climate infrastructure by intercepting solar radiation before it reaches hard surfaces.
Research has shown that shade from mature street trees can reduce asphalt surface temperatures by 15°C to 25°C compared with exposed pavement. By preventing direct solar heating, trees reduce the amount of energy absorbed by road surfaces, helping to limit the urban heat island effect while reducing thermal stress on asphalt.
Lower surface temperatures can also help minimise heat-related softening, rutting and cracking, extending the service life of surrounding infrastructure while creating more comfortable environments for pedestrians and cyclists.
Sources: https://auf.isa-arbor.com/content/46/3/228 https://rosap.ntl.bts.gov/view/dot/58715/dot_58715_DS1.pdf
Cities naturally become hotter than surrounding rural areas because of the concentration of buildings, roads and paved surfaces that absorb and store heat throughout the day.
As climate change increases the frequency and intensity of heatwaves, these effects become more pronounced. Streets designed without adequate tree canopy can experience significantly higher surface temperatures, increasing pressure on transport infrastructure while reducing public comfort.
Recent UK heatwaves demonstrated this clearly, with local authorities monitoring roads that had begun to soften and, in some cases, deploying gritters to spread sand over affected surfaces to protect the asphalt from further damage.
These events reinforce an important message: designing cities that are resilient to heat requires more than reactive maintenance—it requires better urban planning.
Simply planting more trees is not enough.
For street trees to provide meaningful cooling benefits over decades, they must be given the conditions needed to thrive. Restricted rooting volumes, compacted soils and conflicts with surrounding utilities often limit tree growth in urban environments, preventing trees from developing the large canopies that provide effective shade.
This is why engineered tree pit systems have become an essential component of modern streetscape design.
By providing sufficient rooting volume, structural support and sustainable water management, engineered tree pit solutions help trees establish successfully and achieve their full canopy potential.
The result is healthier trees that deliver greater environmental benefits, including:
As temperatures continue to rise, urban designers are increasingly recognising that trees should be viewed as critical infrastructure rather than decorative landscape features.
Healthy street trees contribute to climate adaptation in multiple ways—intercepting rainfall, improving air quality, supporting biodiversity and cooling our cities through shade and evapotranspiration.
For landscape architects, engineers and local authorities, investing in high-quality tree planting systems today helps create streets that remain functional, attractive and resilient for decades to come.
At Greenleaf Ireland, we support projects with engineered tree pit systems and urban landscape solutions designed to help trees thrive—because resilient cities begin below ground.
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