This video explains the basic concepts and theory of the Tornado Safe Room Module of the BCA Tool.
The Tornado Safe Room Module calculates benefits of proposed safe room mitigation projects based on reduced casualties, or reducing the likelihood that a person would be killed or injured in a tornado if he or she did not have access to a safe room. These are also called “life safety” benefits.
Residential safe rooms and community safe rooms are both eligible for funding under some of FEMA’s mitigation programs.
For residential safe rooms, there is a pre-determined cost-effectiveness methodology explained in the Job Aid called “Safe Room Project Application Using Pre-Calculated Benefits”: http://www.fema.gov/media-library-data/1424368115734-86cfbaeb456f7c1d57a05d3e8e08a4bd/FINAL_SafeRoom_JobAid_13FEB15_508complete.pdf.
The rest of this overview looks only at community safe rooms.
The first major variable in the Tornado Safe Room Module is the tornado risk, which is automatically imported into the analysis based on the project location. Projects are more likely to be found cost-effective where there is a risk of large and frequent tornadoes.
Occupancy is the next significant variable in the Tornado Safe Room module. Occupancy data is important not only for properly designing the safe room with enough space, but it also determines the number of people who will be protected from harm. For example, if a safe room is to be constructed just for a school, the occupancy would be the number of students, faculty and support staff, and average number of visitors.
Applications for safe rooms for general public use will have to demonstrate where potential occupants will come from and whether the time and distance for them to reach the safe room meets programmatic requirements.
Another major variable in the Tornado Safe Room Module is the predominant structure type(s) that the safe room occupants will evacuate from. Different structure types have different “wind performance” characteristics, which means the extent they can withstand high winds and protect their inhabitants. Examples include open space like a campground that provides no protection, mobile homes that provide limited protection, and large institutional buildings like hospitals that provide a very strong wind resistance and good protection.
You can select up to two predominant structure types in the module.
For example, a school safe room may be close enough for neighboring residences to also seek safety.
When the tool knows the tornado risk for the project location, number of occupants for the safe room, and the wind performance for the buildings they will be evacuating from, the “Value of a Statistical Life,” or VSL, converts calculated injuries and fatalities into dollar terms.
These dollar values take into consideration costs for hospitalization, lost work productivity, and the long term impact of severe injuries.
The dollar value for the prevented casualties is the Damages Before Mitigation value. Since a safe room constructed to FEMA specifications provide “near absolute protection,” these Damages After Mitigation are assumed to be zero. Therefore, the entire dollar value of casualties prevented by the safe room project are considered project benefits.
This concludes the basic concepts and theory of the Tornado Safe Room Module of the BCA Tool.