Bomb Threats – Why You Should Not Always Evacuate

By Don Williams.

No one knows how many bomb threats are received every month in Australia. It is known that not every threat results in an evacuation, nor does the discovery of an unidentified item always cause the shutdown of the site. Unlike a fire, some incidents do not have an obvious hazard and an equally obvious response. So, on what basis does a manager decide whether to evacuate or not? The use of a defined, defensible assessment process helps the relevant manager, be they Chief Warden, Security, Emergency or Facility manager, decide when to evacuate and when to let the site continue to operate. This article provides a brief overview of the principles that can be used to support the decision.

The argument “better safe than sorry” is used to justify an evacuation every time there is an incident. This is particularly popular with emergency services personnel who do not have to face the consequences of the evacuation. An evacuation is not like a fire drill, where people walk out of the building, get their names checked off and walk back in with minimum disruption. Evacuation has serious implications, risks and real costs.

There is nothing “safe” in moving hundreds or thousands of people in a manner they are not used to; unless they are being moved away from a hazard. Evacuation in many sites requires walking down seemingly endless flights of stairs, an undertaking which, given our ageing and widening society combined with an increased number of health conditions, should only be undertaken if necessary. Australian Standard 3745 (Planning for Emergencies) permits the use of elevators for incidents other than fire but only a small part of the population, usually those with mobility issues, can be accommodated in the time required. Evacuating people may expose them to other hazards as they lead to congestion and crush points at exits; this is particularly true of sporting events, shopping centres and other places of mass gathering. Once evacuated from the building, the people need to be protected from weather, traffic and other hazards, and few emergency plans go beyond getting them out of the door. The placing of hundreds or thousands of people into the urban landscape at short notice has knock-on effects which can be multiplied if other buildings also decide to evacuate, a possibility if the cause is a bomb threat or unidentified item.

Many emergency plans do not provide alternate evacuation routes or assembly areas and wardens are not always trained to decide which route to use and how to direct people to those routes. People will normally want to leave by the way they came or by the route they used in the last fire drill. Some evacuation assembly areas are too close to the site for an explosive hazard so, even when evacuated, people are still at risk. During evacuations, families can be separated causing additional stresses. If there are health centres, aged care or child minding centres on site, then a whole range of additional factors come into consideration.

If an evacuation is initiated, the Chief Warden needs to be confident that all cooking fires, mechanical processes, Hazmat materials and other hazards have been made safe so that the act of evacuating does not create a bigger disaster than the initiating incident. Also, that all secondary hazards (those items existing in the site that are normally safe until acted upon by an event like an explosion) are identified and, if possible, protected. For organisations that hold sensitive information, how to secure hard and soft copy information while evacuating is a real concern. Such factors should be detailed in the site’s emergency plan.

In addition to the human costs of evacuating a site, there are significant financial costs. Evacuating in response to a bomb incident such as an unidentified item will usually result in the site being closed for three hours or more while the emergency services respond to the item. If the evacuation was in response to a threat where no related suspicious item was found, the relevant manager is probably going to be responsible for determining when and how the site will be reoccupied, again probably after a few hours. The result is that every tenant is going to lose the best part of half a day’s productivity, for some this may mean implementing part of the Business Continuity Plan. If the event occurs in the afternoon, local executives or managers need to decide whether it is worth keeping the staff nearby or closing for the day and sending them home.

For performance, cultural or sporting venues, there can be significant costs in refunding tickets and rescheduling the activity. Similarly for universities, evacuating during exam time has costs related to resitting and resetting the exams. Retail outlets need to consider security during the evacuation to prevent theft during the mass movement of people and while the site is empty. Consideration on how the building will be reoccupied should be part of the emergency and security plans.

If the site includes or overlooks public transport links, there can be widespread implications if the transport controllers decide to stop traffic past the site based on an evacuation due to a potential bomb incident.

For some organisations, particularly government agencies, the cost of evacuating is reduced as there is no profit motive and, therefore, they may decide to evacuate on a relatively low level of evidence. Other tenants then have to decide if they will also evacuate based on the first organisation’s assessment. The reality is that if one tenant decides to evacuate, it is difficult, without having access to the information, to decide to remain. In such cases, the other tenants probably have good cause to ask why the initial decision was made to evacuate, on what basis, and to point out the risk and costs incurred as a result.

Managers who make decisions to evacuate should be aware of the implications and consequences of the decision. This does not mean that evacuations should never occur, just that they should be aware of what the decision entails. If there is reason to believe that there is a hazard, particularly a bomb, then the only real safety is provided by distance and by getting behind something solid like another building, preferably not one with large glass facades.

Therefore, the issue becomes one of evacuating only when it is reasonable to believe a hazard is present. Just because a threat has been received, or an unidentified item is found, does not mean that there is a hazard. Managers may find it of benefit to change the traditional wording of the questions. Rather than “Is the threat real” (Hint = it is a real threat) managers should ask “Can the perpetrator have done what they claim?”. Managers should be able to answer this question given their knowledge of the site, awareness of current activities, control over public and secure areas, confidence (or not) in access control systems, ability to talk to front-of-house and other staff, ability to review CCTV and access control records, and the ability to search any nominated areas.

In relation to unidentified items, rather than “How big a bomb could this be?” the question can be “Why would I think this item is hazardous?”. Again managers can answer this question through reviewing CCTV footage and access control systems to determine how it got there, interviewing staff and other witnesses, and having someone look at the item. The decision will then be made that the item may pose a hazard, in which case an evacuation should be initiated, or that the item is rubbish or lost property and should be treated as such.

Some managers will always prefer to be “safe than sorry” and to evacuate; they need to understand the consequences of the decision. Other managers who never evacuate because it is too much trouble, or “they are always hoaxes”, need to be aware of the potential consequences of that decision. In all cases, managers must be able to justify their decision based on a structured process. Additional guidance on how to assess threats and unidentified items is provided in “Bomb Threats – the Manager’s Guide” available through along with the sister publication “Blast: How explosive devices kill people and destroy buildings” which provides a non-specialist understanding of blast effects.

Don Williams CPPRSecP holds qualifications in Security Management and Security Risk Management as well as Project and Resource Management, and is a Certified Protection Professional. Don has provided professional managerial advice on security and strategic security analysis for over 28 years. He has a particular specialty in bomb safety and security. He is a member of ASIS International, the Institute of Explosives Engineers, the International Association of Bomb Technicians and Investigators, and the Venue Managers’ Association. Don can be contacted at



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