Landmark Railway and Conservation Project in a Developing Country: Bangladesh

Norris L. Dodd, Consultant to Asian Development Bank
Asif Imran, EcoConcern Consulting
Karma Yangzom, Asian Development Bank
Mofizur Rahman, Bangladesh Railway
Topic Area
Mitigation for Transportation Projects

Bangladesh is one of the most densely-populated and "poorest" countries in the world, yet has the smallest environmental footprint. This environmental commitment extends to a new railway in SE Bangladesh. Construction of the 102-km Chittagong-Cox's Bazar Railway though 3 protected areas (PA) with endangered Asian elephants (Elephus maximus) began in 2018. We conducted a 2017-2018 study in the PA, accounting for 27% of the alignment, to establish biodiversity baselines, determine elephant distribution and crossing patterns, assess impacts, and develop strategies to mitigate impacts to connectivity, train-associated mortality, and forests. Our foundation was intensive sign (dung, tracks, trails) survey with plot quantification during spring and fall. Wildlife distribution, relative abundance and temporal patterns were elucidated at 20 sites with 38 cameras, operational for 7 months, and capturing 10 species; elephants were most recorded and the only one found at all PA.

Chunati Wildlife Sanctuary (WS) is the largest PA (18,781 ha). While avoiding its contiguous forested "core zone" constituting elephant critical habitat, the 16-km alignment crosses 3 core zone fingers, - the alignment length. They provide vital landscape connectivity to the east; all elephant sign was found here and reflected consistent seasonal use of trails. Preserving connectivity was our primary mitigation goal, especially with deep (7 - 12 m) cuts through ridges to maintain constant railway grade. Here, 2 large (>40 m wide) overpasses will be constructed in the highest-use corridor, with widening of a bridge to accommodate elephant passage. An underpass will be constructed at another high-use corridor. Structures will be linked with funnel fence (3.9 km) integrated with 3 at-grade crossings and animal detection systems to reduce elephant-train collisions. To address potential elephant abandonment from construction, a 0.7-km "quiet zone" encompassing the highest-use area (with overpass) will be deferred from activity until other structures are completed.

At Fasiakhali WS (7,037 ha), the 10-km alignment avoids core zone, passing through forested "buffer zone" interspersed with villages and croplands; this PA has the highest human-elephant conflict (HEC). Elephant use was concentrated along 1.5-km where it abuts core zone, and only during fall. All sign and camera observations reflected crop raiding that extended only a short distance (<100 m) from core zone; no corridors exist beyond the alignment. Preliminary mitigation entailed an overpass and 2 underpasses to promote passage. This was abandoned in lieu of a goal of resolving HEC with a 5-km elephant barrier fence to limit animals to core zone with habitat enhancement. A medium-sized underpass will be constructed at a buffer zone biodiversity hotspot.

This comprehensive railway and conservation project is a landmark one for SE Asia, with 2 of its first wildlife overpasses and its ambitious effort to resolve HEC.

Abstract Keywords
Railway mitigation
Asian elephants
connectivity
human-elephant conflict
overpasses