INTRODUCTION

Building collapses are not uncommon, neither in the United Kingdom or worldwide. Buildings collapse for a variety of reasons. Natural phenomena such as earthquakes, hurricanes, floods, mudslides, avalanches, and storms are the usual cause for multi-building collapses. Single-building events are generally more unexpected, such as the collapse of the department store in Seoul, Korea (June 1995), due to design and construction defects, and the World Trade Centre Towers in New York City (September 2001), due to a terrorist attack.

Search and rescue operations in partially collapsed buildings pose danger to both victims and rescuers because of the possible instability of the remaining building and the rubble's uncertain stability and strength.

The goal of the rescue mission is to retrieve trapped victims while maintaining the safety of rescue personnel.

A BRIEF HISTORY

The devastating 1985 Mexico City Earthquake is often cited as the genesis of Urban Search and Rescue (USAR), for it was the first international rescue event where the problems of search and rescue in large buildings were addressed on a grand scale. During the emergency response effort, most people attempting to rescue victims from the collapsed concrete buildings were untrained, and this situation resulted in the death of many would-be rescuers.

The operations in New York City demonstrated that a great deal of knowledge has been gathered and specialised techniques have been developed from the time of the Mexico City Earthquake. Furthermore, formal urban search and rescue networks have been established. One such network is the International Search and Rescue Advisory Group (INSARAG), which represents USAR teams willing to respond to other countries. The United Kingdom is a member of INSARAG and the UK Government is represented by the UK Fire Service Search & Rescue Team (UKFSSART)..

THE NATURE OF THE BEAST

When a building collapses, it generally does so in one of two ways. The building can be thought of as having "exploded" or "imploded". The primary difference between the two types of collapse is the direction of force as it applies to the materials contained in the structure. It will also assist in a determination of the density of the debris that is involved in the rubble.

With implosion, the building will collapse into itself. It is a technique that is used by demolition specialists to minimise the spread of debris when purposely demolishing buildings. This type of collapse is likely to be caused when interior weight bearing structures lose their integrity and subsequently "pull" exterior walls into the centre of the mass. The density, and generally the depth, of debris are greater when a building is said to have imploded.

In the case of explosion, either caused by an outward rush of force caused by natural, mechanical, or chemical forces, the building will collapse in an "outward" direction. It is likely that the debris will be more wide spread in the vicinity of the collapse, and that it could be of lesser density and depth. A terrorist bomb can "scatter" building parts for several hundred feet or even farther, when it causes a building(s) to collapse. It is possible that victims could be "buried" under debris a greater distance from the centre of mass.

HAZARDS AND RISKS

Partially collapsed concrete structures are probably the most dangerous building types in which to perform search and rescue. These typically large and heavy buildings are difficult to shore and are prone to sudden, catastrophic failures, giving those inside little warning to evacuate. Rescue workers must also consider other hazards besides a building's structural elements.

It must be understood that minor hazards become severe health risks after a structural collapse. For example, emergency lights become flesh-devouring acid pools, yet only appearing as wet spots on walls. The severe dust contains every disease that has been safely buried for the past few hundred years just waiting to find a nice warm moist home in your lungs. Water and sewage systems, electrical wires, and hazardous materials, among others, may pose danger. Some of the would-be rescuers in Mexico City drowned in the basements due to mains water leaks.

One of the biggest concerns during any rescue operation is the level of acceptable risk.

Defining the level of risk to the rescue team, and the trapped victims, is not a simple task. The various disciplines involved often differ on matters of relative risk. To further complicate matters, the level of acceptable risk changes as time passes from the onset of the event; it decreases as the chance of finding live victims decreases.

CONTROLS

The hazards at a collapsed structure incident are many, indeed it is one of the most hazardous of rescues. To maximise the safety of rescuers requires a number of ‘controls’. These are:

• Information – knowledge as the the hazards and techniques to be used,
• Procedures – to ensure a professional, deliberate and structured approach to the incident,
• Supervision – a command & control structure that can bring order out of chaos and provides a safety-based work environment,
• Risk assessment – the hazards are identified, controls put in place and the work system reviewed regularly,
• Training – all rescuers should be trained in techniques, hazard awareness, procedures and equipment operation,
• Equipment – technically advanced equipment will maximise the chances of success whilst minimising risk to the rescuers,
• PPE – all rescuers must be adequately protected – the ‘safe person’ concept.

RESCUE FROM COLLAPSED STRUCTURES

As many as one third of all building collapse victims, that are rescued, are found in spaces created by the way that building materials generally fall. Most of the collapse configurations that occur (displacements, lean-to, V-collapse, pancake) create "voids" in which people may be trapped and remain alive.

The dilemma facing the fire service as the "principle rescue service" is balancing speed and safety. Clearly, whilst a 'New York' situation must be avoided, any casualties still alive after the initial collapse will benefit from a rapid rescue. This places an obligation on the rescue services to act effectively and will require commiting personnel before all safety measures can be put in place.

THE SIX STAGES OF RESCUE

The six stages of rescue provides a framework for the organisation of any collapsed structure incident. It is internationally recognised and is used by a number of international teams including the Americans, Israelis and French. UKFSSART has developed this concept and adapted it for use within the Incident Command System (ICS) operating in the UK Fire Service.

Whilst it is likely that there will not be a clear delineation between each stage and there will be times when stages overlap – the incident command structure must ensure that each stage is undertaken and completed. This logical and progressive approach will mean that rescue personnel do not become drawn into a difficult and protracted extracation of one individual when nearby there are twenty people only trapped by a wedged door. It is imperitive that a cost / benefit analysis drives the decision making process, particularly in the early stages of an incident and the rescue services must be prepared to accept the fact that they may not be able to rescue everybody.

Progression through the Six Stages will take a considerable time even at a small single dwelling collapse. Tactical planning should take account of this and the resouces required to acheive a safe and succesful conclusion to the incident. Pre-planning must take account of the equipment and techniques required, the training implications that result and the overall supervision and control of the incient.

There is no quick solution to the problem - purchasing vibraphones or concrete drills will not make any fire brigade competent to deal with collapsed structures even on a lesser scale than that witnessed in New York.

UKFSSART has both experience and operational credibility in this area of operations and provides a resource to the UK Fire Service through the Fire Services Inspectorate and CACFOA.

Consider using it.

For further information concerning this article and structural collapse rescue please e-mail the author.