Tag Archives: wait times

How Fast is TSA Pre Check?

23 Apr

We compared wait time values between regular lanes at TSA and TSA’s new PreCheck lanes. For a quick reminder, TSA PreCheck is an expedited screening experience for those deemed to be low risk travelers. While other countries and airports have been doing this for years, TSA finally realized that not every traveler – especially those crafty invalid military veterans, 85 year old seniors, and unaware toddlers – are armed to the teeth with explosives. In exchange for $85 and a prescreening at a physical TSA office, passengers can jump into the TSA PreCheck club. Benefits include keeping your shoes on, keeping your jackets on, and not having to remove liquids and electronics from your bags. You also get to use a metal detector instead of the cancer-fomenting back scanners.

TSA PreCheck works by “carving” out PreCheck lanes from the regular lanes. No new lanes are being built as most airports only have so much real estate available. So the same number of travelers are still processing through the same number of lanes: it’s just that the speed of the PreCheck lanes are *hopefully* faster.

And thus far, they are…. but, there’s a caveat! TSA developed the PreCheck program in October 2011. Since then, it’s been reported that a little over 1 million travelers have signed up, resulting in 30 million visits to PreCheck lanes. If you remember that the US receives 2 million daily travelers at its airports, 30 million is a trivial number. As of this post, there have been 1.86 billion travelers that have passed through US airports since PreCheck’s inception. 30 million thus represents 1.6% of the airport visits.

While admittedly a very slow going adoption curve for a “superior” service, what happens if more people sign up for PreCheck? It is possible that the PreCheck lines could become slower than the regular lines as more people sign up. Without active management of the queues, TSA could become a victim of its own success. More people would have been processed through the old, regular lane than are currently being processed in the new PreCheck lane. So actually, wait times have increased for the time being.

Now the data! We looked at a year’s worth of data across several airports. We examined the maximum wait time for PreCheck lanes against the maximum wait time for regular lanes during the same 30-minute periods. On average, here are the results:

- The waits at PreCheck lines are longer than the regular lines ~4% of the time

- The average wait for a PreCheck passenger is ~36% of the wait for a regular passenger

Bluetooth’s Shortcomings at Highlighting Airport Wait Times

22 Sep

Several airports have tried using hardware solutions to determine TSA security wait times. We’re still not convinced real-time waits are as important as understanding what the wait time will be like when you get to the airport. Nonetheless, there are parties who spend hundreds of thousands of dollars  implementing these solutions.

Bluetooth technology is designed to pick up signals from devices that have Bluetooth enabled. Each device has a unique signal so the device can be tracked. Airports set up the Bluetooth receivers to identify when a phone first enters a security line, and when it exits. The problem has been two fold. First, not many devices have Bluetooth enabled. Second, determining if a unique device is actually in line or just somewhere near the line has proven problematic.

The below chart shows the wait time results from a Bluetooth installation at Indianapolis International Airport. Bluetooth would tell us that there were multiple waits over 1 hour in duration for a given day. This is entirely inaccurate. Don’t believe it? Let’s look at some sample data from Bush Intercontinental Airport, where we can see how many gaps exist in Bluetooth data.

We can see the large gaps in device signals from the Bluetooth data from Bush International. This particular image was generated from Terminal D on May 31st, 2013. Many times the Bluetooth system picks up ghost devices: devices where there’s an entry or exit signal, but not the corresponding converse.

IAH Bluetooth Data Terminal D

IAH Bluetooth Data Terminal D

The quality of Bluetooth is suspect. It misses many passengers who may have their Bluetooth devices off and the system has a difficult time pinpointing device location accurately. The good news is that the Houston Airport System spent less than a million dollars on this Bluetooth system – we’ve seen tax dollars spent more poorly before.

You can see the full purchase order here: HAS Bluetooth costs

Forecasting Airport Security Wait Times

20 Sep

Over the past year we’ve spent a good chunk of time working with various stakeholders to build a giant algorithm that forecasts airport security wait times. But how does it work?

Think about a security line as a bucket of water. There are droplets of water falling in the bucket, and a little hole in the bottom of the bucket where water drips out. The drops into the bucket are the passengers arriving at security and the drops out are the passengers processed by TSA. So how do you know when and how many drops fall into the bucket, and when and how many drops drip out?

Passengers arrive for a departure in a bell curve shape. The first passenger might show up 2 hours before his flight. The next person arrives 4 minutes later and then five people arrive 2 minutes after that. Overall you’ll see a nice bell curve. The bell curve, however, can change! Things like weather, times of year, and even the type of traveler (i.e. business traveler v.s. budget airline traveler) can influence what the bell curve looks like. Luckily we have years of data that help us understand how these external factors influence the bell curve.

Airport Bell Coruve

Airport Passenger Arrival Bell Curve

When you understand how passengers arrive, you can next turn to how they are being processed. In 2004 the TSA contracted IBM to build SAM, or Staffing Allocation Model. This model tells TSA how to staff to process passengers to minimize airport security wait times. You can learn how much this cost the TSA here.

The net output is an algorithm that understands how passengers arrive at the airport, and how they’re processed. All you need is a consistent feed of flight departures and you can determine the wait times at each checkpoint where TSA staffs. For our particular UI, we give the maximum wait for a 30 minute period. Over time we will fine tune this to 15 minute periods, but as of now it’s a great place to start.

And that’s how you can put math to work!