Security as a mathematical model

Can security checks at airports be made more pleasant and more cost-effective for passengers? How can their security be improved? These are the kinds of questions being addressed by security research in the context of the German Government's High-Tech Strategy.

Enlarge image Full body scanner (© picture-alliance/dpa) Full-body scanners were hotly debated in the press. According to current scientific knowledge, long-wave radiation is an entirely safe means of penetrating clothes and representing physical contours in precise detail on a screen. But no one in Germany wants to expose their body to airport security staff in that way. The newspapers were full of provoking and rather unaesthetic images taken by the body scanners.

What is security worth to me?
These devices have been in use in the United States for quite some time now, but resistance is starting to grow. Those passengers who do not wish to be scanned are subjected to a thorough body search. The main reason is the 9/11 terrorist attacks. Since then the need for the maximum possible security has been felt to be greater in the United States than in Germany. Security is a subjective matter, as is the question of how much I am willing to pay for that feeling of security.

Given how expensive the body scanners are, airport operators and the general public are faced with a completely different question, namely whether they are worth the money. A feeling of security is highly rated, but what is it actually worth? Security costs are already a key factor in the price of a plane ticket. Equipping all airports with new scanners will further increase the cost of flying and thus lead to a drop in airline passengers

Enlarge image Airport Security Check (© picture-alliance/dpa) And so we are faced with a complicated economic and mathematical problem that involves very subjective factors. Researchers at EADS in Ottobrunn south of Munich are developing a mathematical model to solve just that problem. The German Ministry of Education and Research (BMBF) is supporting this research as part of a project entitled 'Improving the Security of Transport Infrastructure'. Others taking part in the collaborative project include Munich Airport, the Fraunhofer Application Centre for Logistics System Planning and Information Systems (ALI) in Cottbus and Technische Universiät München.

Working out the cost of security
The material damages resulting from a plane crash are used to compare costs and benefits. That might sound cynical, because what's the price tag on a human life? Nevertheless, the costs can be calculated when they are based on the damages insurance companies have to pay. It is, of course, easier to work out the value of an aeroplane and the damage caused when it crashes into a house. Researchers working on this project put the sum of these costs on one side of the scales.

On the other side they put the costs for additional equipment, for instance those that can identify explosives and require additional personnel. What connects the two sides of the scale is the probability of a terrorist attack with and without the new equipment.

The model includes very many parameters: How many people each year attempt to smuggle weapons into Munich Airport with the intention of hijacking a plane? How many people are caught each year carrying a banned item without the intention of committing an offence? Those responsible at Munich Airport have seen the statistics, but they are subject to the strictest confidentiality.

Confidential data

Enlarge image The lonely crowd (© dpa/pa) Researchers on the project haven't seen the statistics, though. They had the choice of working with the concrete data under the strictest confidentiality or of developing a model that uses fictitious data. They chose the latter, since that allowed them to share information with scientists at international level as well as to inform the general public. As the real data for the models are not known to researchers, they will make the model available to the airport operators, initially to Munich Airport, a project partner, so they can apply the real data. The project partner can then determine what improvements to security measures promise the greatest benefits.

The scenarios attempt to incorporate all possible access routes and potential perpetrators' motives. For example, not only passengers are regarded as at risk, but also airport staff or those who force an entry into the airport. Possible motives are politically motivated terrorist attacks against the aeroplane, using the aeroplane as a weapon or hijacking a plane as a means of fleeing. Known risk factors include hand luggage, dangerous objects on a perpetrator's person, as well as bombs in hold baggage or in airfreight. An attack can also be carried out against airport buildings or an aeroplane. Blinding pilots with laser pointers is usually a stupid school-boy prank, albeit a very dangerous one.

235 million Euro for more security
The Security Research Programme was launched in 2007. Since then the BMBF has provided 235 million Euro in funding towards citizens' civil security. The programme is not purely technical, that is it is not only about technical innovations. Several projects are also dealing with innovative organisational strategies and strategies for action. Researchers and practitioners from diverse fields are cooperating closely on the programme, which fits into the framework of European research policy.

It looks like a solution has been found for body scanners in Germany: The computer screen does not display the actual image, but analyses it and then shows a stylised representation indicating where a suspicious object is located on the person's body.