Mark Lynch, a terrorism expert with Aon Benfield’s Impact Forecasting division, recently explained the work he and his team have done in modeling the potential effects of terrorist-related explosions. He noted advances in the field and called for wider use of the modeling technique.

“Blast modeling has improved exponentially, and the insurance industry needs to use it,” he told delegates at a session during the recent Impact Forecasting conference in London.

Lynch explained CFD during the conference, noting that the type of explosive used, the weight/volume of the charge and where it could potentially be placed all have to be considered in creating the models. “The blast [pressure] wave propagates through urban geometry—i.e., where the force of an explosion goes is where it finds the space to do so,” he said. “Tracking the pressure impulse curves enables us to calculate the damage.”

“The difference in the curves also depends upon the type of construction and the materials used,” he said. The most serious damage—level 3—is a total building collapse, which is also the cause of the greatest loss of life.

In addition to the direct property damages caused by a blast, indirect consequences—business interruption and denial of access to the damaged premises—can result. In some cases it can cause contingent business interruption.

The new models are constructed not only to predict potential paths of damage but also to identify weaknesses in planning and construction changes that can mitigate losses. The models Lynch is working on also incorporate “electronic mass casualty assessment and planning scenarios (EMCA & PS).”

These are global applications that can be used to construct models anywhere in the world, he noted.

“We’re not constrained by geography here,” Lynch told Carrier Management after listing the U.S., France, the U.K., Germany, Australia, Singapore and South Africa as areas for which Aon Benfield has CFD blast models. “This tool can be applied anywhere—to any setting, any environment. And the model development is quite quick, he added, estimating that a request for a blast model for Los Angeles, for example, could be met within a two-week time frame as opposed to several months.

With older models, “the market is still relying on a conservative archaic approach to understanding peak risk exposure,” Lynch said in the interview. “What we’re trying to do is take code that has been prevalent in the military realm…for numerous years and bring it into the insurance market to help the quantification of risk. Effectively, what that really means is moving away from an approach that relies on 250-meter circles of 100 percent loss and actually switching to looking at how the blast may interact with the environment,” he said, summarizing the essence of the CFD approach that couples an assessment of blast pressure and movement with building vulnerability.

With limited data on building vulnerability, insurers and reinsurers may have to be conservative in their approach to risk. “But where there is more information on the resilience and the protection of the building itself, such as window lamination or offsetting bollards to make sure there are no vehicles that can get close to the environment, we can start to incorporate that for a more in-depth analysis that colleagues at Weidlinger Associates are providing,” the Aon Benfield expert said, referring to assistance from a structural engineering firm.

During the conference, Lynch introduced Nick Misselbrook, a Weidlinger associate who heads the company’s modeling and simulation team in the U.K. Misselbrook, a specialist in vulnerability assessment and consequence analysis of structures to terrorist attacks, focused on past attacks during his presentation, including graphic pictures of the extent of damage caused by the Oklahoma City bombing and the attack on the twin towers of the World Trade Center.

The attack on the Alfred P. Murrah Federal Building on April 19, 1995, killed at least 168 people, injured more than 680 others, destroyed or damaged 324 buildings within a 16-block radius, as well as setting cars on fire and shattering glass. Estimated damages were $652 million. It was the most serious terrorist attack in the U.S. until the attack on the World Trade Center.

Misselbrook’s most harrowing slide, which few in the audience will forget, was a very realistic simulation of an exploded aircraft inside one of the World Trade Center buildings. He explained that the buildings weren’t brought down by the force of the crash or the explosion of tons of kerosene fuel but by the fire which destroyed any systems capable of suppressing it, resulting in the weakening and eventual collapse of both structures.

These tragedies offer lessons in what incorporating preplanning scenarios in building construction and location might achieve in reducing loss of life and property damage. Misselbrook, whose expertise includes counterterrorism design, pointed out that while U.K. standards mandate blast and structural analysis of larger buildings, the U.S. does not. This isn’t surprising, however, given that building codes vary from state to state and from city to city.

It is entirely possible to prevent and mitigate some of the damage from bomb blasts. Lynch explained that even one millimeter of laminate on windows has a dramatic impact on the scale of losses. “Simply putting a plastic sheet over the glass, you can effectively reduce the likelihood of demolishing or collapsing and also dramatically reduce the loss of life [by minimizing] the amount of sharp fragments that fly out,” he said.

The first concern remains the structural integrity of the buildings. There are designs that can minimize the possibility of a building collapsing because there are weak parts in the structure that can give way and trigger a total collapse. There are ways such as barriers to underground parking garages that would seal off some of the most vulnerable areas of attack.

All of those measures and more begin with “protective assessments,” Lynch said. Unfortunately, the insurance and reinsurance industry has been slow to incorporate this kind of analysis before policies are issued. It’s time that it realized the value of doing so, he argued.

In the U.K., however, Pool Re, the cooperative reinsurer set up by the government after a series of IRA bombings in the 1980s and ’90s, encourages insurers to conduct these analyses by giving discounts on premiums for those who do a “full building analysis.”

It’s often said that “where there’s a will there’s a way.” As far as blast mitigation is concerned, Lynch and others have described a number of ways. Now it seems that what’s needed is the will.