The project review pipeline at Vermont Agency of Transportation already includes several features that lead to better outcomes for wildlife. Resource identification is done before the scoping process and several structural connectivity models flag road segments with a high likelihood of wildlife passage. Furthermore, Vermont’s collaborative public-private partnership between state agencies and conservation NGOs has provided years of camera studies and other research that indicates sizing and structural design that facilitate wildlife movement. This system offers some prioritization in flagging which structures are most important for wildlife but fails to provide a larger context of how a particular structure compares with other infrastructure that’s out there. As the Vermont Agency of Transportation moves toward system-wide improvements to its infrastructure that meet the needs of fish & wildlife as well as flood resilience, cost-effectiveness, and other important values, understanding of that larger context is important in allocating resources.
Vermont’s new Terrestrial Passage Screening Tool (TPST) ranks all the bridges and culverts on the state system with respect to facilitating wildlife movement. The tool relies on statewide omniscape modeling and includes scores for landscape context, site-level conditions, and structure characteristics. This tool is the most recent step in a long series of efforts that Vermont has undertaken to better understand the interaction of roads and wildlife and fits into a larger state conservation design. The TPST is especially useful in assessing whether to rehabilitate or replace an ageing culvert as it offers that larger context of the landscape and site characteristics. The tool will also prove useful in identifying existing infrastructure with high landscape and site scores but poor structure scores that might be easily retrofitted. There are still more questions that need answering to help the Agency assess the value to wildlife of one structure or another. The question of proximity and redundancy are not yet addressed and will to our understanding as system-wide improvements continue.