OOH glossary · Measurement
Dwell time
Dwell time is how long a person stays near an ad and can see it. A highway gives little dwell time, so the ad needs few words.
OAAA defines dwell time as the time a person is close to an OOH ad. The IAB-led DOOH glossary uses it for time spent in a venue, like an airport.
Long dwell lets you use more words. A highway gives short dwell, so it needs few words and big letters.
In digital billboard rules, dwell can also mean how long each ad stays on screen. Many states set a minimum, so check with your state DOT.