New Delhi: An internal geological assessment prepared before the Wayanad tunnel tragedy had warned that the hillside above the project’s North Portal faced an imminent risk of collapse, raising serious questions over whether the disaster could have been prevented.
The landslide struck the tunnel construction site near Kalladi Meppadi in Kerala’s Wayanad district on Tuesday, killing six people. The assessment, completed by technical experts involved in the project, documented alarming signs of instability at the very location where the tunnel entrance was being developed.
The report found that the slope consisted of nearly 35 metres of loose silty soil resting above solid rock. With poor natural drainage, the soil was highly vulnerable to heavy rainfall, allowing water to accumulate beneath the surface and significantly weaken the hillside. Engineers recorded widening cracks across several sections of the slope, ground subsidence, muddy water seepage and cavities forming within the soil.
One of the most concerning findings was the sound of underground water flowing beneath the slope, indicating internal erosion that was steadily washing away the soil from within. The report warned that these conditions could trigger a sudden slope failure at any moment, particularly on the left side of the North Portal, which was identified as the most dangerous section.
The assessment also revealed shortcomings in the site’s safety systems. Many drainage holes designed to release trapped water were either ineffective or non functional, while critical monitoring instruments to detect underground pressure had not yet been installed. Existing monitoring equipment was found to be inadequate in reflecting the extent of the slope’s deterioration.
Although controlled tunnel blasting took place during the inspection period, engineers concluded that vibration levels remained within safe limits and that continuous monsoon rainfall was the primary factor behind the worsening slope conditions.
The report recommended immediate stabilisation measures, including construction of gabion retaining walls, installation of protective coverings across exposed slopes, improved rainwater diversion channels and testing of soil anchors and drainage systems under saturated conditions. It also advised relocating a nearby concrete mixing plant, warning that its weight and heavy vehicle movement could further destabilise the fragile hillside.
Construction at the North Portal was halted after the report highlighted the growing danger, several days before authorities officially ordered work to stop. Following the fatal landslide, work at the remaining portal has also been suspended as experts review safety measures before construction can resume.
