Surface grading is commonly performed by bulldozers and motorized surface graders, but it can have detrimental effects on tree roots and vegetation. In the context of road construction, efficient earthwork techniques are necessary for creating stable slopes and minimizing environmental impact. Today we will explore the consequences of surface grading on tree roots and outline modern approaches to earthwork in road construction.
Surface Grading and Tree Root Damage
Root Damage from Surface Grading
Surface grading operations, such as leveling areas around structures and roadways, often result in significant damage to tree roots. Bulldozers and motorized graders can tear and damage roots, while trunks may be scraped or harmed during the process. Surface vegetation, including small trees, bushes, and leaf litter, is frequently scraped off, and topsoil containing feeder roots is often removed.
Concealed Root Injuries
Surface grading damage to tree roots is often concealed by the application of turf or a layer of mulch. However, close inspection may reveal trunk and buttress area damage caused by tractor blades or treads. Even surface grading near existing trees in wooded lots is likely to harm their roots, and any large construction machinery moving around trees can also cause root damage.
Consequences and Detection of Tree Root Damage
Impact on Tree Survival
While many trees survive surface grading with minor crown symptoms, severe damage or loss of feeder roots, topsoil, and humus layers can lead to tree mortality. Turf growing on a thin layer of soil can exacerbate the damage by competing with injured tree roots for nutrients and moisture, hindering root regeneration and healing. Detection of surface grading damage can be determined by obtaining the construction activity history in the affected tree’s surroundings.
Long-Term Site Changes
The loss of topsoil and feeder roots due to surface grading can result in long-term site changes that further impact tree health and survival. The growth of turf on top of a thin layer of soil can hinder root recovery and exacerbate the damage. Preventative measures or remedial actions should be considered in areas where surface grading has occurred or cannot be avoided to mitigate long-term effects.
Earthwork Techniques for Road Construction
Hydraulic Excavators and Attachments
Modern road construction techniques employ hydraulic excavators coupled with advanced drilling and blasting technologies. The excavator’s versatility allows for various tasks, including digging, swinging, dumping, ripping, trenching, loading, compacting, and hydraulic hammering, by utilizing different attachments and buckets.
Reduced Dependency on Blasting
The powerful breakout power of hydraulic excavators reduces the need for extensive blasting during earthwork operations. Blasting is often minimized or unnecessary due to the excavator’s capabilities and proper drilling equipment, which enables vertical and horizontal drilling.
Steepness of Cut and Fill Slopes
Constructing cut and fill slopes with the desired steepness is an extremely important step in road construction. Steeper cut slopes require more excavation, resulting in higher construction costs and potential slope collapse. Careful consideration of slope angles based on soil and rock types is necessary if you want to avoid erosion and slope failure.
Takeaway
Surface grading during road construction can have significant implications for tree roots, leading to root damage and potential tree mortality. The right use of hydraulic excavators with various attachments and modern drilling techniques reduces the reliance on blasting, providing greater control over the excavation process. Also the careful consideration of cut and fill slope steepness helps prevent erosion and slope failure, ensuring stable and environmentally responsible road construction practices.