Not using a required turn signal before turning, changing lanes, or moving from a parked position.

"Required" matters because drivers are not expected to signal every twitch of the steering wheel, but they are expected to warn others before a movement that could affect nearby traffic. "Turn signal" means the vehicle's signal lamps or hand-and-arm signal when allowed. "Before turning, changing lanes, or moving from a parked position" covers the everyday situations that cause side-swipe and rear-end crashes when other drivers, cyclists, or pedestrians have no warning. In Kansas, K.S.A. 8-1548 (2024) requires an appropriate signal before turning or moving right or left on a roadway and says a signal of intention to turn must be given continuously during not less than the last 100 feet traveled before the turn.

Practically, a failure-to-signal ticket can be more than a minor annoyance. It can help an officer justify a traffic stop, support a finding of driver negligence, and become part of the record after a crash. In heavier traffic areas such as Johnson County, where lane changes happen fast and often, that missing signal can be the detail everyone ends up arguing about.

For an injury claim, failure to signal may be used as evidence of negligence or comparative fault. If one driver changed lanes without warning and a collision followed, that violation can affect who is blamed, how damages are divided, and how an insurer evaluates the claim.