How verification works

The question every funder asks about a carpool program is "how do you know they really carpooled?" This page is the answer, in terms you can repeat.

The short version

Each participant's phone records their drive on the Big Sky corridor roads automatically, a GPS point every few seconds. When two participants' recordings of the same road at the same time stay within a few meters of each other for the whole drive, they were in the same vehicle. That is a verified shared trip. Nobody logs anything, so there is nothing to forget and nothing to exaggerate.

Why it is hard to fake

Two cars driving one behind the other look close on a map but are not close in the data. At canyon speeds, a car one minute behind is more than a kilometer back. Two phones in one car stay within a few meters of each other for 45 minutes straight, through every curve.

Before the platform was built, this was tested on real recordings from US-191: drives from phones that were in one car ran a median of 2 to 26 meters apart for the entire canyon, while cars that were merely close in time ran hundreds of meters apart. There was almost nothing in between. The platform counts a pair as one vehicle only when the typical distance is under 50 meters and nine in ten points are within 120 meters, leaving a wide margin on both sides.

The app itself is checked too: the platform confirms each upload comes from a genuine copy of the app on a real phone, so recordings cannot be typed in or generated by a script.

What it cannot tell

Verification proves that two enrolled phones travelled in one vehicle. It cannot see who is holding them. Someone who enrolled two phones and carried both would look like a carpool.

The platform watches for exactly that pattern: real carpool partners are sometimes apart (days off, a drive alone, a weekend errand), while two phones in one pocket never are. Pairs that are never seen apart over many trips appear on the Review page for you to check. Employer join codes help as well, since an employer knows whether two names are real staff.

Late uploads

A phone that finishes its drive in the canyon's dead zone uploads when it next has signal, sometimes the next day. Its partner's trip may show as "driven alone" until then, and becomes shared automatically when the second recording arrives. Participants see the same thing in the app, with an explanation.

Bus trips

The first version verifies car trips. Skyline bus trips will be verified against Skyline's real-time bus location data once its new system is live.

Where to read more

Your platform contact can provide the full verification document, which gives the thresholds, the evidence kept for each decision, and the test results.