operations research for homeland security and beyond!

Operations Research for Homeland Security

and Beyond!

Laura Albert McLay, PhDAssociate Professor

University of Wisconsin-MadisonIndustrial and Systems Engineering

[email protected]@lauramclay

http://punkrockOR.com

Laura Albert McLay, June 4 2016 ISYE 50th Anniversation Reunion @ UW-Madison

mailto:[email protected]


Executive summary

Security research investigates how to use scarce resources for screening aviation passengers, cargo containers, etc., in low risk, cost-constrained environments.

Better security is achieved by targeting scarce screening resources at the “riskiest” passengers and doing less screening on most passengers.

Research has informed policy at the TSA, technical analysis underlying TSA Precheck implicitly focuses on risk targeting, which is why it makes the air system safer, in low risk, cost-constrained environments.


Aviation security: Past, present, and future


1938!!

One hijacking encourages

copycats:Hijackings are

contagious

Metal detectors and X-ray machines go in place


A brief history of passenger screening

• Dawn of time until 1970• Not much!

• 1970• Surveillance equipment, air marshals

• Feb 1972• Armed guards to make people feel safe• Screened by behavioral profile, metal

detector, and ID check• Dec. 1972

• Metal detector / magnometer


A brief history of passenger screening

• 1996• Checked baggage for high-risk

passengers screened for explosives (run by airlines)

• Passenger-baggage matching rejected• Motivated by Pan Am Flight 103 (1988)

and TWA Flight 800 (1996)

• Sept. 2001• Times are a changin’


Security is a moving targetChanges in passenger and baggage screening

• November 2001 – Aviation Transportation and Security Act• Created the TSA• Required all checked baggage to be

screened for explosives, Dec. 2002 deadline

• December 2001• Remove shoes

• 2002 +• CAPPS II, Secure Flight, etc. for risk-

based screening


Security is a moving targetChanges in passenger and baggage screening

• August 2006• No more liquids after liquid

explosives used in a bomb attempt

• 2009 - 2010• TSA starts using explosive trace

portals

• September 2012• Less screening for seniors (75+) and

children (<12)

• December 2013• TSA Precheck for reduced security


Checked baggage security before 2001

• Early discrete optimization research dates back prior to September 11, 2001

• Checked baggage for high-risk passengers screened for explosives• Selectee and non-selectee screening

• Goal was how to optimally deploy and use limited baggage screening devices


Checked baggage security models

Flight segment = flight between takeoff and landing of an aircraftA flight segment is:

• uncovered if 1+ bags on the flight has not been screened• covered if all selectee bags on it have been screened

Baggage screening performance measures developed in conjunction with the Federal Aviation Administration:• Cover the most flights.• Cover the most passengers on covered flights.• Cover flights by fully utilizing the devices.


Checked baggage security models

The Uncovered Flight Segment Problem (UFSP):Find a subset of flights to screen such that we maximize the total amount of covered flights subject to a screening capacity.

The Uncovered Passenger Segment Problem (UPSP):Find a subset of flights to screen such that we maximize the total amount of passengers of covered flights subject to a screening capacity.

The Uncovered Baggage Segment Problem (UBSP):Find a subset of flights to screen such that we maximize the total amount of bags screened subject to a screening capacity.

Policy implications?


Important questions

What if you have to• Take transferring passengers into account?• Distribute screening capacity to airports and screening stations?• Distribute screening capacity to airports and screening stations in

discrete pieces?• Consider weapons of mass destruction (WMD), not just

conventional attacks?

Discrete optimization can answer all of these questions!


Checked baggage challenges in 2001

State of the art• Existing explosive detection system devices from two manufacturers• Old technology for screening passengers

Limitation• Current technology is slow and not effective• Not enough space for security and security lines in airports• Infrastructure needed to screen baggage in-line

Ultimate goal• Good screening devices• Fast screening (< 10 minutes)• Do all this in < 14 months!!

The solution was haphazard & piecemeal

• Explosive trace detection• Uses mass spectroscopy or ion mobility spectroscopy • Labor intensive when bag is swabbed


Why are homeland security problems good ISyE problems?

• Limited resources• Passenger risk assessments• Human screeners• Tradeoffs among criteria (efficiency, security, cost)

• Note: TSA has a goal of <10 minutes waiting for screening• System and goals are always changing

We will always have security challenges, and ISyE/DSOR tools will always help us address some of these challenges.

Security often improved through deterrent effect, not detection.


What about screening passengers?


Risk-Based Passenger Screening

Passenger risk assessments have been used since 1996.

Most passengers are low-risk.

What is known: As risk increases, likelihood of a security threat outcome increases.

Risk-based security: Captured in the Dynamic Aviation Risk Management System (DARMS) paradigm.

Risk-based screening vs. Random screening

How do we do it?Laura Albert McLay, June 4 2016 ISYE 50th Anniversation Reunion @ UW-Madison

Risk-based Screening Framework

Know everyone’s risk before they enter security screening; allocate security resources to match risk.Final Assessments:

Was there a successful attack?Was the system being tested?

How do match limited screening resources to passengers?Assumptions:

Security resources are limited.Screening procedures make errors

* False alarms, False clears.Laura Albert McLay, June 4 2016 ISYE 50th Anniversation Reunion @ UW-Madison

How can passengers be assigned?

Ahead of time:* Integer programming models1

In real-time:* Markov Decision Processes2

* Control Theory models3

Based on the Sequential Stochastic Assignment Problem (SSAP)Security resources allocated to a passenger match the retrospective security resource allocation.

1 McLay, L.A., Jacobson, S.H., Kobza, J.E., 2006

2 McLay, L.A., Jacobson, S.H., Nikolaev, A.G., 2009

3 Lee, A.J., McLay, L.A., Jacobson, S.H., 2009


Real-time simulation of optimal policy

Time

Passenger risk


Risk Profiles of screening classes

Passenger riskLaura Albert McLay, June 4 2016 ISYE 50th Anniversation Reunion @ UW-Madison

Conditional distribution of passenger risk assessment

values

Screening Procedure Reality

Three possible scenarios:

1. Right Screening

2. Under Screening

3. Over Screening


What if you get it wrong? Will the system be more vulnerable?

Overestimating risk*: True risk level < estimated risk level

When risk is overestimated, high value security resources get used on low risk passengers, which may leave fewer high value security resources available for high risk passengers.

Underestimating risk: True risk level > estimated risk level

When risk is underestimated, high value security resources get used on high risk passengers, which targets more closely the high value security resources for high risk passengers

* tendency is to overestimate riskLaura Albert McLay, June 4 2016 ISYE 50th Anniversation Reunion @ UW-Madison

Key observations

Right Screening is ideal, but challenging to attain for all passengers.

Better security is achieved by targeting scarce screening resources at the “riskiest” passengers and doing less screening on most passengers.

TSA Precheck implicitly focuses on reducing screening for some to target resources at “risky” passengers, which is why it makes the air system safer, in low risk, cost-constrained environments.


Gaming StrategiesBlockingOvertaxing / decoysTimingTrial and Testing

All can disrupt the system in limited resource environments


Bad intentions

We are trying to prevent attacks

Is the goal to identify non-threat passengers with banned items or threat passengers with bad intentions (and no banned items)?

Risk based security focuses on the latter


Final thoughts

• Risk reduction, not risk elimination

• If you cannot find a needle in a haystack, make a smaller haystack• Target limited resources at a small haystack


Security systems

http://www.tsa.gov/about-tsa/layers-securityLaura Albert McLay, June 4 2016 ISYE 50th Anniversation Reunion @ UW-Madison

How to schedule Federal Air MarshallsHow to randomly staff checkpoints at an airport

In the news: we need DSORQueueing and scheduling


In the news!


Live at 4 on WISC-TV, May 31, 2016http://www.channel3000.com/news/Professor-talks-about-science-to-traveling-airport-lines/39814720

http://www.channel3000.com/news/Professor-talks-about-science-to-traveling-airport-lines/39814720

http://www.channel3000.com/news/Professor-talks-about-science-to-traveling-airport-lines/39814720

Thank you!

Laura Albert McLay, PhDAssociate ProfessorUniversity of Wisconsin-MadisonIndustrial and Systems [email protected]@lauramclayhttp://punkrockOR.com


Blog posts:Aviation security, there and back againAviation security: is more really more?

mailto:[email protected]


https://punkrockor.wordpress.com/2015/07/24/aviation-security-there-and-back-again/

https://punkrockor.wordpress.com/2015/06/03/aviation-security-is-more-really-more/

References

Jacobson, S.H., McLay, L.A., Kobza, J.E., Bowman, J.M., 2005, “Modeling and Analyzing Multiple Station Baggage Screening Security System Performance," Naval Research Logistics, 52(1), 30-45.Jacobson, S.H., McLay, L.A., Virta, J.L., Kobza, J.E., 2005, “Integer Program Models for the Deployment of Airport Baggage Screening Security Devices," Optimization and Engineering, 6(3), 339-359. McLay, L.A., Jacobson, S.H., Kobza, J.E., 2006, “A Multilevel Passenger Screening Problem for Aviation Security,” Naval Research Logistics, 53(3), 183-197.McLay, L.A., Jacobson, S.H., Kobza, J.E., 2007, “Integer Programming Models and Analysis for a Multilevel Passenger Screening Problem, “IIE Transactions, 39(1), 73-81.Nikolaev, A.G., Jacobson, S.H., McLay, L.A., 2007, “A Sequential Stochastic Security System Design Problem for Aviation Security,” Transportation Science, 41(2), 182-194.McLay, L.A., Jacobson, S.H., Kobza, J.E., 2008, “The Tradeoff between Technology and Prescreening Intelligence in Checked Baggage Screening for Aviation Security,” Journal of Transportation Security, 1(2), 107-126.McLay, L.A., Jacobson, S.H., Nikolaev, A.G., 2009, “A Sequential Stochastic Passenger Screening Problem for Aviation Security,” IIE Transactions, 41(6), 575-591 (2009 Outstanding IIE Publication Award).Lee, A.J., McLay, L.A., Jacobson, S.H., 2009, “Designing Aviation Security Passenger Screening Systems using Nonlinear Control,” SIAM Journal on Control and Optimization, 48(4), 2085-2105.McLay, L.A., Lee, A.J., Jacobson, S.H., 2010, “Risk-Based Policies for Aviation Security Checkpoint Screening,” Transportation Science, 44(3), 333-349.


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