Standard Gauge Railway Wildlife Underpasses — Tsavo Conservation Area, Kenya

Kenya's Chinese-financed Standard Gauge Railway (SGR), built 2014–2017 between Mombasa and Nairobi, was routed on a raised embankment through the unfenced Tsavo Conservation Area — habitat for Kenya's largest single elephant population (about 12,800 animals) and dozens of other large mammal species.
To allow wildlife movement across the line, engineers incorporated 141 crossing structures over the Voi–Mtito Andei and Voi–Bachuma sections: 14 bridges, 58 culverts and 69 lower embankment openings. Save the Elephants, working with the Wildlife Research and Training Institute and Kenya Wildlife Service, has run continuous camera-trap and tracking monitoring since 2016.
A peer-reviewed study (Scientific Reports, 2022) covering June 2016–October 2019 recorded 33 medium-to-large mammal species using the structures, with elephants (30.5% of bridge crossings), plains zebra (20.2%), baboon (12.4%), buffalo (7.6%) and dik-dik (7.7%) the most frequent users. Underpass height was the strongest predictor of use — taller structures were used more — and electric fencing raised use by most species except elephants; livestock presence cut wildlife use of a structure by roughly half.
The record is mixed. Save the Elephants documented eight elephant deaths from collisions with the solid embankment in the monitoring's early period, against a prior average of about two per year from road traffic in the same area — evidence that, where the line was not elevated or fitted with adequate openings, the railway increased risk rather than reduced it. Independent reviewers (including National Geographic's 2016 reporting) criticised the original design process for inadequate ecological assessment before construction. The case is included here as an evidenced example of both what worked (height-adequate, monitored crossings used by most target species) and what did not (long embankment sections with insufficient openings), useful for railway planners elsewhere in East Africa.

Read the full analysis: https://savetheelephants.org/our-work/science/monitoring/sgr-underpass-monitoring/