Heavy rain has washed away the causeway over the Balason river at Dudhia in Mirik subdivision, disrupting the direct movement of heavy vehicles between Siliguri and Mirik and forcing them on to longer alternative routes.
The causeway, located around 30km from Siliguri, was built over Hume pipes and was damaged by the force of the swollen river early on Friday. An official of the Mirik subdivision said around 57mm of rain had been recorded in Mirik by early morning, raising the Balason’s water level and causing the structure to fail.
The same causeway had earlier been washed away on June 19 after the Balason swelled. The Indian Army and the West Bengal public works department subsequently built a Bailey bridge next to the damaged site to maintain essential connectivity between the hill subdivision and the plains.
The 58-metre-long and 3.75-metre-wide Bailey bridge has a load capacity of nine metric tons. It remains open to light vehicles and two-wheelers, allowing residents and other travellers from Mirik and the plains to continue using the crossing. Heavy vehicles that previously used the causeway, however, cannot cross and will have to take alternative routes.
A source in the state PWD said heavy vehicles bound for Mirik would be routed through Sukhiapokhri, Ghoom and Kurseong. The authorities have also reconstructed the damaged causeway, but the restriction on heavy vehicles remains because the Bailey bridge is not designed to carry them.
The disruption comes while the state PWD is constructing a permanent bridge over the Balason. The earlier concrete bridge at the location collapsed and was swept away in October 2025. The new bridge is scheduled for completion by February 2027.
According to a state PWD official, deck slabs on both sides of the new structure have been completed, while work on the middle span is yet to begin. The department has decided to proceed cautiously after a sudden rise in the river’s water level last year swept away the entire middle portion of the old bridge. The official said work on the middle span was expected to accelerate after the following month, with completion targeted within the existing deadline.
The rain also damaged another temporary causeway at Tabakoshi over the Rangbhang river in Mirik subdivision. The Sukhia block administration has stopped vehicles from using that damaged bridge. Road connectivity between Sirikhola and Rammam through Daragaon in Darjeeling district’s Pulbazar block also remains cut off after a landslide.
Further damage was reported in the Lower Sangmoo area of south Sikkim’s Rangang-Yangang constituency after persistent rain on Thursday night. A team led by Bishnu Sharma, additional political secretary in Namchi district to Chief Minister Prem Singh Tamang, visited the affected area with district administration officials to assess the damage.
The India Meteorological Department has forecast continued adverse weather across north Bengal until September 14. An IMD official said thunderstorms with lightning and gusty winds of around 40km per hour were expected across north Bengal, while Sikkim was likely to receive light to moderate rain over the next 72 hours.
