Building Smoother Rides: Why Pavement Performance Starts Beneath the Slab
by Natalie Springfield, on September 05, 2025
When it comes to highways and roadways, one complaint consistently tops the list: a rough ride. Cracks, bumps, ruts, and potholes aren’t just surface issues, they usually trace back to the ground beneath the pavement. Even the most precise paving operation won’t last if the subgrade isn’t stiff, stable, and uniform.Why Smoothness Matters
Smoothness isn’t just about driver comfort—it’s a key performance indicator tracked by Departments of Transportation (DOTs) and contractors alike. The International Roughness Index (IRI) is the standard measure, and DOTs often tie contractor incentives or penalties directly to it.
A smoother road surface means:
- Lower vehicle operating costs (fuel, tires, suspension wear).
- Longer pavement life and fewer costly overlays.
- Reduced maintenance budgets for agencies.
- Higher public satisfaction with new projects.
In fact, research shows that pavements built smooth and kept smooth last longer and deliver better life-cycle value.
Problems Start Beneath the Surface
Subgrade variability is a silent but powerful driver of roughness. Weak or inconsistent support creates differential settlement, rutting, and faulting at joints. Once surface irregularities begin, they only worsen under traffic and environmental cycles.
Common subgrade-related causes of roughness include:
- Differential settlement from variable soil stiffness.
- Rutting from repeated truck loading on soft spots.
- Swelling/shrinkage of clays with moisture cycles.
- Freeze-thaw heaving in poorly drained soils.
The bottom line: if the foundation isn’t uniform, the ride won’t stay smooth.
The Geogrid AdvantageThis is where Tensar geogrid stablization makes a measurable difference. Installed at the subgrade–aggregate interface, geogrid interlocks with the base aggregate, creating a mechanically stabilized layer (MSL) that improves long-term performance.
Key benefits include:
- Load Distribution: Geogrid spreads vehicle loads over a wider area, reducing subgrade stress and minimizing permanent deformation.
- Aggregate Confinement: Lateral restraint limits movement of base stone, keeping the layer stiffer and more stable.
- Rutting Control: Large-scale testing and field studies show geogrid-stabilized sections experience shallower rut depths and slower IRI growth compared to unreinforced sections.
- Uniform Platform for Paving: Contractors benefit immediately with a stable, rut-resistant platform that supports paving equipment and reduces delays caused by soft spots.
Field performance studies have shown that geogrid-stabilized road sections consistently maintained lower IRI values and smoother rides years after construction, compared to adjacent sections built without stabilization.
Unlike lime or other chemical treatments—which can be messy, weather-sensitive, and hit-or-miss depending on soil conditions—geogrid is fast, clean, and reliable, giving crews a stable platform to pave on and helping roads stay smoother under traffic.
Simple, Proven Installation
The process is straightforward: prepare the subgrade, roll out the geogrid, place and compact aggregate, then pave. Contractors report faster progress, fewer delays after rain, and more predictable performance once the road opens to traffic.
The Bottom Line for DOTs and Contractors
Uniform support equals uniform performance. By investing in a geogrid-stabilized base, DOTs and contractors can deliver smooth pavements from day one—and keep them smooth for years to come. The result: lifecycle cost savings, satisfied road users, and fewer maintenance headaches.