4.4.1 Evacuation Types

Several important factors should be considered when making a decision to evacuate an area, but the primary consideration is the potential risk to lives and property. The type of evacuation will be based on the situation. Evacuations are generally classified as one of three types:

• Voluntary evacuation (Figure 4.4.1.1) – issued toward populations that are most vulnerable to the threat or other specific populations that may need lengthy lead-times to complete evacuation requirements (e.g., offshore workers, persons on coastal or barrier islands). Generally, no specific traffic management measures or special transportation arrangements are implemented during voluntary evacuations, and people may remain in place if they so choose.

• Recommended evacuation (Figure 4.4.1.2) - issued when an event has a high probability of causing a significant impact to populations located in at-risk locations. Decisions to evacuate are left to individuals; traffic management measures and special transportation arrangements may be implemented based on the number of evacuees and needs of the population.

• Mandatory evacuation (Figure 4.4.1.3) - issued when the jurisdictional authority anticipates an imminent threat to life safety. Ingress to the impacted area will typically be limited to first responders. Special transportation management plans such as contraflow lane reversal and use of shoulders as additional lanes may be implemented. Special transportation arrangements will be activated when evacuation transportation plans go into effect. Mandatory evacuations are often difficult to enforce as many residents will challenge orders by government officials to evacuate their homes and property.