Wednesday, 3 August 2016

Airport Security, can more be done with less?


One of the main news items of the past few days is the increased level of security at Amsterdam Schiphol Airport and the additional delays it has caused travellers both incoming and outgoing. Extra security checks on the roads around the airport are being conducted, also in the airport additional checks are being performed. Security checks have increased after the authorities received reports of a possible threat. We are in the peak of the holiday season where around 170.000 passengers per day arrive, depart or transfer at Schiphol Airport. With these numbers of people for sure authorities want to do their utmost to keep us save, as always. This intensified security puts the military police (MP) and security officers under stress however as more needs to be done with the same number of people. It will be difficult for them to keep up the increased number of checks for long. Additional resources will be required, for example from the military. Question is, does security really improve by these additional checks or could a more differentiated approach offer more security (lower risk) with less effort?

How has airport security evolved?

If I take a plane to my holiday destination …I need to take of my coat, my shoes, and my belt, get my laptop and other electronic equipment out of my back, separate the chargers and batteries, hand in my excess liquids, empty my pockets, and step through a security scanner.  This takes time, and with an increasing numbers of passengers waiting times will increase. We all know these measures are necessary to keep us save but taking a trip abroad doesn’t start very enjoyable. These measures have been adopted to prevent the same attack from happening again and has resulted in the current rule based system of security checks. Over the years the number of security measures has increased enormously, see for example the timeline on the TSA website, making it a resource heavy activity which can’t be continued in the same way in the near future. A smarter way is needed.

Risk Based Screening

At present most airports apply the same security measures to all passengers, a one size fits all approach. This means that low risk passengers are subject to the same checks as high risk passengers. This implies that changes to the security checks can have an enormous impact on the resources requirements. Introducing a one minute additional check by a security officer to all passengers at Schiphol requires 354 additional security officers to check 170.000 passengers.  A smarter way would be to apply different measures to different passenger types, high risk measures to high risk passengers and low risk measures to low risk passengers. This risk based approach is at the foundation of SURE! (Smart Unpredictable Risk Based Entry) a concept introduced by the NCTV (The National Coordinator for Security and Counterterrorism) Consider this, what is more threatening, a non-threat passenger with banned items (pocket knife, water bottle) or a threat passenger with bad intentions (and no banned items). I guess you will agree that the latter is the more threatening one and this is exactly where risk based screening focusses on.  Key component in risk based security is to decide what security measures to apply to which passenger, taking into account that attackers will adapt their plans when additional security measures are installed.

Operations Research helps safeguard us

The concept of risk based screening makes sense as scarce resources like security officers, MP’s and scanners are utilized better. In the one size fits all approach a lot of these resources are used to screen low risk passengers and as a consequence less resources are available for detecting high risk passengers. Still, even with risk based screening trade-offs must be made as resources will remain scarce. Also decisions need to be made in an uncertain and continuously changing environment, with little, false or no information. Sound familiar? This is the exactly the area where Operations Research shines. Decision making under uncertainty can for example be supported by simulation, Bayesian belief networks, Markov decision and control theory models. Using game theoretic concepts the behaviour of attackers can be modelled and incorporated, leading to the identification of new and robust counter measures. Queuing theory and waiting line models can be used to analyse various security check configurations (for example centralised versus decentralised, and yes centralised is better!) including the required staffing. This will help airports to develop efficient and effective security checks limiting the impact on passengers while achieving the highest possible risk reduction. These are but a small number of examples where OR can help, there are many more.


Some of the concepts of risk based security checks, resulting from the SURE! Programme are already put into practice. Schiphol is working towards centralised security and recently opened the security check point of the future for passengers traveling within Europe. It’s good to know that the decision making rigour comes from Operations Research, resulting in effective, efficient and passenger friendly security checks. 
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