The Kilometer That Broke the Corridor

When a 12‑kilometer stretch of road can grind an entire 90‑kilometer corridor to a halt, the math of risk becomes a story about geography, weather—and choice. In transport networks, where continuity matters as much as capacity, the most consequential failures are often compact, repeatable, and weather‑driven. They rarely arrive as headline‑making catastrophes; more often they are the steady, costly interruptions that erode livelihoods, supply chains, and regional resilience. At Grid Engineers, we built INFRARRED to make those interruptions visible, quantifiable, and—crucially—preventable.

Why cascade risk matters for transport ?

Transport corridors are systems of interdependence. A landslide on a single critical segment can cascade into hours‑ or days‑long delays, rerouted freight, stranded commuters, and economic losses far exceeding the direct cost of clearing debris. Traditional assessments stop at susceptibility mapping—where slopes are steep, soils weak, and vegetation thin—but planners need to know when slopes will fail, how much material will move, and how shifting rainfall patterns will change exposure.

INFRARRED treats landslide risk as a physics-based, weather‑linked problem and reframes assessment from static zoning to dynamic forecasting. By blending historic trigger data with hydromechanical principles, the model produces actionable thresholds—specific rainfall intensities and durations that, when exceeded, are expected to destabilize a calculable volume of soil. The system:

• Assesses risk on road cuts and embankments with pinpoint accuracy.
• Links rainfall intensity and duration to estimated volumes of displaced soil, informing cleanup-cost and mitigation design.
• Predicts changes in landslide exposure under shifting rainfall patterns.
• Differentiates shallow from deep‑seated slides to enable targeted early warnings and engineering responses.

How we applied INFRARRED in Djibouti?

For the World Bank’s Horn of Africa Initiative (Djibouti Regional Economic Corridor Project), we combined high‑resolution susceptibility mapping with rainfall‑trigger modeling to move from “where slides might occur” to “when they will, how much soil will move, and which segments will interrupt traffic.” The results were striking:

The analysis made the invisible visible. INFRARRED pinpointed the corridor’s critical 12‑km stretch near Arta and Ali Sabieh as the primary driver of weather‑related closures, quantified the typical volumes of displaced soil for different rainfall scenarios, and translated those physical outputs into dollar impacts.

Baseline annual losses from closures were estimated at roughly $1.5M; under plausible future climate scenarios, frequent smaller slides could push annual losses toward $6.3M. Those are not abstract probabilities — they are predictable, repeatable interruptions that impose steady costs on communities and commerce.

Armed with that specificity, planners could prioritize with surgical precision. A recommended $2.4M portfolio of targeted interventions—combining retaining structures and drainage upgrades, nature‑based slope stabilization, preventive clearing of unstable surface material, operational measures tied to early‑warning rainfall thresholds, and short rehabilitations of key secondary detour links—reduced expected annual losses by an estimated $11.8M, producing a benefit–cost ratio of 5.5.

In short: a focused investment on the right segments delivered outsized resilience returns.

What that meant on the ground

• Fewer repeated closures. Stabilizing the hotspot segments and reinforcing feeder routes kept traffic moving, reducing direct cleanup costs and indirect economic losses from disrupted supply chains.
• Smarter, locally appropriate choices. Differentiating shallow versus deep‑seated failures allowed the team to select NbS where they would last and grey works where necessary, matching solutions to hazard type and local feasibility.
• Operational readiness. Early‑warning thresholds tied to 24‑hour rainfall volumes created a practical trigger for temporary closures, pre‑emptive clearing, and mobilization of crews—minimizing surprise and response time.

The Djibouti corridor showed that resilience is not always about heroic, corridor‑wide interventions—it’s about knowing where a few targeted actions will break the chain of cascading failure.