I’ve been a state DOT project manager for over 18 years, overseeing highways, bridges, and slopes across several counties. Nothing sharpens your focus like having a major route on the brink of collapse—and that’s exactly what happened last winter.
During a routine maintenance drive, a technician spotted subtle sagging along a steep fill slope adjacent to the highway. Within days of heavy rain, cracks had spread several feet, sending alarms through our team. If nothing was done, we weren’t just looking at slope failure—the roadway itself was at risk.
We immediately paused all heavy maintenance and called in a geotechnical consultant specializing in landslide hazard assessment. Their team hit the ground running, deploying drones for aerial imagery, ground-penetrating radar scans to identify subsurface anomalies, and moisture probes to measure saturation levels.
The results were clear: the original fill had consisted of mixed materials—some compacted, some dumped—which created a layered structure prone to sliding when water built up. Rain had elevated pore water pressure in the middle zone, triggering the failure.
Next, they developed a thorough geotechnical slope analysis. This included stability modeling under three scenarios: current saturated conditions, projected seasonal maximums, and a 10‑year storm event. The analysis showed a factor-of-safety below acceptable limits—meaning the slope was likely to continue moving without intervention.
Given the data, they recommended an engineered soil nail wall combined with horizontal drains to quickly lower water pressure behind the slope. They also suggested regrading the existing drainage ditch to reduce runoff infiltration during future storms.
We briefed the emergency state highway committee and secured funds within 10 days. Construction began immediately. The soil nail wall went in during off-peak hours, and drainage improvements followed. The entire stabilization was completed in under a month, minimizing disruption.
Stability metrics confirmed the solution worked. Within weeks, monitoring data showed a 40% drop in water pressure and zero additional movement. The highway remained open, and more importantly, trusted by the community.
But the benefits didn’t stop there. We used the opportunity to update our standard protocol. Now any abandonment of slopes near state right-of-way must include regular landslide hazard assessment and geotechnical slope analysis as required parts of design and maintenance packages.
I still drive that route regularly. I don’t see the cracks anymore—but I know they’re being watched. And that makes all the difference.
