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Good practice Imported

Dedin Green Bridge — Wildlife Overpass Monitoring on the Zagreb–Rijeka Highway (Croatia)

Croatia · Delnice · See the Croatia profile

Evidence: Observational / pre–post Top 76% 33/100 · Ask Evidence Copilot about this practice

A 100 m-wide green bridge over the Zagreb–Rijeka highway (Gorski Kotar) recorded 12,519 wildlife crossings across 793 monitored days (15.8/day) by bears, wolves, lynx and ungulates, per peer-reviewed camera-trap, track-pad and infrared monitoring studies.

12,519
Wildlife crossings logged at Dedin bridge (793 monitored days)
15.8
Average crossings per day
83.2 %
Share of crossings by ungulates

Details

Maturity
Established
Promoter
Croatian Motorways (Hrvatske autoceste); University of Zagreb Faculty of Veterinary Medicine
Period
2005-2011
Keywords
road ecology, wildlife connectivity, large carnivore conservation, infrastructure monitoring

Context

Croatia's Zagreb-Rijeka highway (A6) cuts through the core forest habitat of Gorski Kotar; engineers included a single purpose-built 100m-wide green bridge at Dedin alongside 43 viaducts and tunnels to keep bears, wolves and lynx connected.

Activities

Infrared-sensor monitoring at Dedin logged animal crossings over 793 active monitoring days; a separate three-year study (2009-2011) at four other A6 green bridges compared track-pads, camera traps and infrared detectors as monitoring methods.

Results

12,519 animal crossings were logged at Dedin (15.8/day average), with ungulates accounting for 83.2% of movements and large carnivores 14.6%. Radio-tracking found bears, wolves and lynx strongly preferred large tunnels and viaducts over small underpasses, and researchers documented the first hard evidence of regular, repeated overpass use by three distinct wolf packs.

Conclusions

The Dedin bridge's usage matched its available share of the landscape, indicating the purpose-built structure performed acceptably but was not markedly preferred over the highway's other large structures — a design lesson now used to size future crossings.

Implementation
Indicative cost
High (€500k–€5M) — Cost of the green bridge not disclosed separately from the wider A6 motorway construction.
Time to results
Long (> 3 years) — Monitoring conducted 2009-2013 across multiple studies; the bridge itself is permanent highway infrastructure.
Staffing & skills
Croatian Motorways (Hrvatske autoceste), University of Zagreb Faculty of Veterinary Medicine researchers

Conditions for success

  • Wide (100m) purpose-built overpass design rather than narrow underpasses
  • Multi-year infrared/camera-trap monitoring to validate use by target species

Commonly funded by

National / regional programmes

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Data sources

Where this practice's information was retrieved from, and when.

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