2020 Critical update to Caltrans wildfire vulnerability analysis

The data and materials presented here support a research project conducted
by UC Davis in support of Caltrans, a transportation agency that
is conducting a wildfire vulnerability risk assessment for fuels
reduction in the right of Way (ROW) to protect Caltrans’ infrastructure
and travelers. We reviewed the 21 layers used in a 2019
fire risk model and updated input spatial data as available. We
then reran the risk assessment for 2020 and developed an
updated risk map. The risk map was used to rank the highway
network into 4 classes: Top 10%, top 17% (cross comparable with the 2019
priority routes), top 20%, & top 30%. Here is the abstract from
the associated report. Catastrophic wildfires over the past five years
(2015-2020) have caused damage to the Caltrans road network in 81 separate
wildfire events, leading to expenditures of over $590,000,000 to repair
highway assets.  To reduce the risk of further wildfire damage
and to improve public safety, particularly for disadvantaged communities,
Caltrans has engaged in assessing the priority locations for vegetation
treatment within the lands it owns called the Right of Way (ROW). A 2019
analysis provided a map showing the top 17% of vulnerabilities in the road
network, representing both the risk of wildfire and to disadvantaged
communities that might need to use the transportation network as means of
evacuation. This UC Davis research project was designed to support efforts
within Caltrans in conducting a wildfire vulnerability risk assessment for
fuels reduction in the right of Way (ROW) to protect Caltrans’
infrastructure and travelers. The project involved four components: 1)
conducting a rigorous peer review of the 2019 GIS-based study commissioned
by Caltrans; 2) collecting and assessing the outputs of several climate
change, fire, and other models currently developed or under development
for California, as well as future climate projections; 3) developing a
framework for the use of the prioritized segment model with other data
further identify priority areas for fuels and risk reduction; and 4)
interviews with Caltrans staff on opportunities and obstacles to
increasing the pace and scale of vegetation treatments. The results
contribute to infrastructure risk assessments, can be used to prioritize
areas for treatment, to create a tracking system of areas treated and risk
lowered over multiple years, and to engage local governments and wildfire
fighting units to coordinate landscape fire risk reductions.