On the surface, a pothole may appear to be a simple problem caused by wear and tear. But in truth, deep potholes often stem from a series of hidden or neglected issues beneath the road surface. Understanding these underlying causes is essential for long-term pavement management, especially in regions like Mount Barker, SA, where weather, traffic, and infrastructure age all play a part.
At Mount Barker Road Tech SA, we work with councils, businesses, and private landowners to not only repair potholes but to prevent them at the root cause. Below, we explore the most common hidden triggers of severe pothole formation and why early intervention is key.
Water Infiltration: The Silent Destroyer
Moisture is one of the most aggressive forces acting on asphalt surfaces. When water seeps through small surface cracks, it infiltrates the underlying layers, disrupting the compacted base and weakening the structure from below.
This causes:
- Erosion of the sub-base
- Softening of supporting materials
- Loss of cohesion between asphalt layers
In colder climates, this problem worsens due to freeze–thaw cycles, but even without freezing, trapped moisture will lead to accelerated pavement failure and pothole collapse.
Poor Drainage Design or Blocked Runoff Paths
Even a well-laid asphalt surface won’t perform if water has nowhere to go. Insufficient or poorly maintained drainage can lead to pooling, which accelerates surface wear and provides more opportunities for infiltration.
Warning signs include:
- Standing water after light rain
- Damp edges along the road
- Cracks forming near kerbs and gutters
Pavements without efficient water management deteriorate faster and require more frequent repairs.
Subsurface Voids and Soil Movement
Asphalt is only as strong as the foundation it rests on. Below the surface, a range of ground issues can trigger deformation that eventually becomes visible through potholes.
Common causes include:
- Voids left by decaying organic material
- Settlement due to improperly compacted fill
- Expansive clay soils shrinking in dry conditions
- Tree root activity beneath the pavement
These shifting conditions result in undetected structural instability, which eventually presents as subsidence or cracking at the surface.
Neglected Cracks and Minor Surface Damage
Small cracks are easy to overlook, especially when traffic continues to move freely. But every crack is a vulnerability. Once left open to water and vehicle pressure, those cracks grow, connect, and eventually break away pieces of the road surface.
Delayed surface maintenance allows:
- Minor failures to spread across wider areas
- Edges to become ragged and break off
- Pavement layers to delaminate
Proactive crack sealing and surface sealing can prevent these small issues from escalating into full-scale potholes.
Heavy Traffic Concentration in Localised Zones
Areas with concentrated vehicle movements—such as loading bays, bus stops, or intersections—experience more pressure than standard traffic zones. Without reinforcement, these areas degrade rapidly beneath the weight of repeated loads.
Indicators include:
- Depressions or ruts along tyre paths
- Flaking or shoving near turning zones
- Rapid progression from surface cracks to craters
Targeted resurfacing or strengthening is required in such high-stress zones to avoid deep pothole development.
Conclusion
Deep potholes are not simply the result of wear and tear—they’re symptoms of hidden issues beneath the asphalt. Moisture, poor drainage, unstable subgrades, neglected surface damage, and repetitive heavy loads all work in tandem to accelerate the breakdown of the pavement
Call us on: 08 6727 9106
Click here to find out more about Mount Barker SA
Click here to complete our contact form and see how we can help with your Asphalt and Bitumen Surfacing needs.
