Definition
A taxiway centerline marking that, in the area approaching a runway holding position marking, is supplemented by a pair of yellow dashed lines flanking each side of the normal solid yellow centerline. The enhanced portion extends up to 150 feet prior to the holding position marking, providing a visual cue that the aircraft is approaching a runway hold short location.
Plain English
A regular yellow taxiway centerline that, near a runway, has dashed yellow lines added on both sides of it. These extra dashes are a heads-up that you are getting close to a place where you must stop and check before crossing onto a runway.
Context Anchor
Seen while taxiing toward a runway entrance or runway crossing, just before the runway holding position marking.
Derivation
Enhanced' comes from Old French enhauncier, meaning to raise or heighten. Here, the standard centerline is 'raised' visually by adding the flanking dashes — making the approaching hold line harder to miss.
Why Pilots Care
Provides a clear visual cue that reduces the chance of accidentally entering an active runway.
Intuition Check
Do not read “enhanced” as meaning the centerline has a different route or gives you permission to continue. It means extra warning marks have been added near a runway so you notice the upcoming stop area sooner.
Example Sentence 1
As we taxied toward Runway 27, the enhanced taxiway centerline marking appeared, reminding me to slow down and look for the hold short line ahead.
Example Sentence 2
In low visibility the enhanced taxiway centerline marking helped confirm the aircraft remained on the correct path toward the ramp.