What makes Brooktrails and Sherwood Ranch in Willits, Calif., so vulnerable is a lack of exit routes out of these areas when disaster strikes.
Following nearby fires in 2017, community leaders learned that “none of the four ‘emergency travel routes’ shown on the official evacuation map were available for use,” said Keith Rutledge, a member of the steering group for Sherwood Firewise Communities (SFC), an organization formed to improve fire-zone safety in the area. “And this notification came after the fires were put out. This left the 5,000 people and 2,000 homes with only one way in and out — Sherwood Road.”
Streetlight Data, a traffic analysis software firm, took a close look at 30,000 communities across the country with fewer than 40,000 residents — locations where there’s likely to be a limited number of highways into and out of town — to get an understanding of their risk to natural disasters and load volume of local roadways. The study ranked the top 100 communities by “evacuation risk” from the point of view of transportation.
Sherwood Ranch was one of those communities. The Mendocino Council of Governments completed a Fire Vulnerability Assessment and concluded with the Brooktrails and Sherwood Communities as “the most dangerous residential area in Mendocino County,” said Rutledge. Several years ago, the area had only one official evacuation route. The SFC began the process of identifying and clearing previously abandoned emergency access routes.
“During the past two years, two of the four routes have been secured under a memorandum of understanding authorizing access for vegetation and route management for emergency use only,” Rutledge explained.
The research by Streetlight Data shows that routes into and out of a smaller town are few and that many of those routes are routinely operating at 70 percent, or higher, capacity under normal circumstances. Which may be fine for everyday use, but when disaster strikes and residents have to be exited out of the community quickly, bottlenecks can endanger fleeing residents.
“The belief is that habitually, you’re used to taking certain roadways out of your city boundaries, and when disaster strikes and where evacuation happens, people are likely to follow the road that they know … unless there are procedures in place to route them in a particular direction,” said Martin Morzynski, vice president of marketing and product management at StreetLight Data.
“Essentially, the fewer the exits and the bigger the load on the biggest exit, the higher the risk,” he added.
The message for all involved in disaster planning, company officials said, is to ensure all routes are open and free of obstacles, particularly when secondary routes could serve as entry points for firefighters and other first responders.
The recent Oak Fire, which burned more than 1,000 acres in Mendocino County, prompted the evacuation of the Sherwood communities, which went smoothly, said Rutledge. Also, having additional fire routes allowed fire crews to quickly stage equipment in necessary areas. And consequently, the fire was controlled.
“I think it goes to show how this information can highlight areas of risk, and spur activity to create resilience, planning and bolster evacuation plans,” said Morzynski.
Zooming out and analyzing data that examines risk across a state or region offers planning officials a tool to strategize risk mitigation efforts, Morzynski added.
“The example of CalFire is particularly relevant, because the value of information, in these big data sets, is to look at an entire state and ultimately identify a community at the highest risk,” said Morzynski.
“That’s where the power of big data comes in,” he added. “Because it allows you to narrow down your choices, or how do you deploy resources. It’s the same old prioritization game, that I think is relevant to larger organizations.”
The 10 U.S. communities with the most constrained evacuation routes are:
- Camano, Wash.
- Hilton Head Island, S.C.
- Mercer Island, Wash.
- Skidaway Island, Ga.
- Nahant, Mass.
- South Beach, Fla.
- Six Shooter Canyon, Ariz.
- Pahrump, Nev.
- Bell Canyon, Calif.
- New Square, N.Y.
