After a natural disaster such as Hurricane Katrina the need for communication is great. Emergency workers must communicate efficiently and effectively with other relief workers to be able to do the greatest good. The utmost priority is to minimize loss of life, and that is precisely what responders aim to do when post-disaster inspections of buildings are performed.
In many communities, officials placard and mark structures after inspections. But, what are those colored placards and spray painted X’s that adorn buildings after a disaster? The placards are postings by building officials that indicate what condition the structure is in. The large X’s are marks made by Federal Emergency Management Agency (FEMA) Search and Rescue Teams during and after searching for victims of the disaster. This article briefly describes the meaning and use of these markings.
Green, yellow, and red placards are used by the local building officials to designate what types of restrictions are imposed on the building. The system of placards was developed by the Applied Technology Council starting in the late 1980’s. Their publications—ATC-20 Procedures for Post Earthquake Safety Evaluation of Buildings, ATC-20-1 Field Manual: Post Earthquake Safety Evaluation of Buildings, and ATC 45 Field Manual: Safety Evaluation of Buildings After Windstorms and Floods—establish a standard of care when performing rapid or detailed post disaster inspections. The system described in ATC-20-1 has been widely used on the West Coast after earthquakes. It was first used in 1989 in response to the Loma Prieta Earthquake when the City of San Francisco building officials realized that they did not have enough building inspectors to evaluate the thousands of damaged buildings. ATC-20-1 provides a consistent and systematic method for inspecting structures, and reporting the damage. After the Northridge Earthquake in 1994 hundreds of engineers that were trained in ATC-20 volunteered to inspect buildings in the Los Angeles basin. Given these successes, ATC completed the ATC-45 training program in response to Hurricane Katrina.
The following are brief descriptions of the intent of the placards:
Green—The building has been inspected and no restrictions on use or occupancy have been found. The placard includes the date of inspection and inspector’s identification number. An evaluation form is prepared and given to the building official. Events after the inspection, such as severe weather or aftershocks, could require additional inspections and a change of the placard.
Yellow—The building has been inspected and found to be damaged as described on the placard. This placard can be used as a catchall to cover a wide range of hazards that may limit use of the building or portions of the building but not make it completely unsafe. Examples of such hazards include water saturated ceiling drywall, collapsed chimney on a portion of the roof or creating a falling hazard on an adjacent structure, electrical power lines that had been inundated during flooding, or a portion of the building has collapsed but other portions do not appear to have been damaged. A yellow card may allow for limited use of the building for removal of property, but restrict continuous habitation or sleeping in the building.
Red—The building has been inspected and is damaged and unsafe. No entry is allowed, except as specifically authorized in writing by the jurisdiction. A red placard does NOT imply that the structure is condemned and must be demolished. Repairs can be made to mitigate the hazard. Specific hazards are noted on the placard and may include falling hazards, hazardous materials, loss of safe exits or a potential for collapse.
It should be emphasized that the placement and removal of placards need to be performed under the authority of the controlling jurisdiction such as a building official, if there is such authority. In the event of a major disaster, it is expected that the local jurisdictions will be overwhelmed. In that case, inspectors may be brought in from outside the area and be preferably paired with employees from the local jurisdiction to facilitate interaction with the public and explaining the reasons for the posting.
The ATC-20-1 and ATC-45 Field Manuals describe the differences between rapid and detailed building evaluations. The rapid evaluation procedure is primarily an assessment of the exterior of the structure and identifies if the building is apparently safe, unsafe or should have restricted use. Often after a disaster it is important to allow people to return to as many of the affected buildings as possible because of a shortage of shelter and housing. The ATC Inspection protocols can be used to quickly determine if a building is habitable. If it is not apparent what the condition of the building is, then a detailed evaluation may be required. A detailed evaluation includes visual observations of the external walls, cladding, parapets, and foundations; observation of geotechnical conditions; inspection of the internal structural framing, including vertical and lateral load carrying components; inspection for non-structural hazards such as falling ceiling tiles, or hazardous material spills; and any other potential hazards like debris blocking the exits. The ATC-20-1 and ATC-45 recommend that all essential facilities such as hospitals, or fire stations receive a detailed inspection if any damage is suspected.
Placarding buildings after a disaster can be performed according to the protocols described in the ATC-20-1 and ATC-45 Field Manuals and provide a systematic means to inform the public about the safety of, or restrictions on, building usage. More information on these topics can be obtained from the ATC website at www.atcouncil.org.
Search and Rescue markings
FEMA has established 28 Urban Search and Rescue (USAR) Task Forces throughout the country. USAR Task Forces are trained and equipped to search for, and rescue, victims after a disaster. The Teams consist of firefighters, sheriffs, communications specialists, doctors, canine search teams and structural engineers. Teams have been mobilized for numerous disasters including the Murrah Building Bombing, the World Trade Center Collapse, Hurricane Floyd, and Hurricane Katrina. These Teams are deployed within days of the disaster and come with the resources to search neighborhoods, search individual buildings, locate survivors and safely extract survivors through the use of shoring and other devices.
The USAR Task Force System was conceived after the 1985 Mexico Earthquake when, after the first three days after the disaster, more people died trying to rescue people than were rescued. Structural engineers are included in deployments to assist in searching buildings and determining the shoring required for the safety of the rescuers. As they perform search operations, the USAR Teams spray paint a large “X” on the structure to indicate the status of their efforts. The quadrants of the “X” are used to indicate when the structure was searched, which task force performed the search, what hazards are present, and how many victims are trapped in the building. If the trapped victims can not be easily removed, then the USAR teams bring in equipment to remove debris and carefully shore up the structure to prevent further collapse during the rescue.
After Katrina, FEMA USAR teams from 15 states carried out hasty/primary searches and secondary searches. The goal of the hasty/primary searches was to find and evacuate victims in the first 12 days after the hurricane. Later, secondary searches were conducted door to door in areas where flooding was higher than 5.5 feet above the floor of the buildings. Buildings were entered and re-secured during the secondary searches. More information on FEMA urban search and rescue teams can be obtained from the FEMA website at www.fema.gov/emergency/usr/about.shtm.
Over the last two decades systematic methods for searching and inspecting damaged buildings have been developed. The evidence of these methods are the spray painted X’s, and brightly colored red, yellow, and green placards that appear prominently on the walls of buildings after a disaster. These are respectively, the evidence of Urban Search and Rescue Operations by FEMA, and Structure Safety Evaluations sponsored by the local building officials. You can expect to see these marks and placards more frequently after future disasters as the benefits of their usage becomes better known by jurisdictions across the United States and the rest of the world.
Paul A. Brallier, S.E., P.E., is a structural engineer at HNTB Corporation in Bellevue, Wash. He is a member of the Structural Engineer’s Association of Washington’s Disaster Preparedness and Response Committee, an ATC-20 instructor, and former member of FEMA USAR WA-TF-1.