Platform GAP

On the way back home on the train, I thought I noticed a slight difference in the door announcements. Not too sure, but did they include platform now?

Opening? Too inviting. People might want to step into it.

Crevice? Too narrow. People's foot won't step into it anyway.

Ravine? Too organic.

Trench? Too military. The guys might start doing fire movement.

Moat? Too defensive. Then must invite people to step across with a drawbridge.

Drain? No water.

Crack? Too crooked.

Hole? Maybe, but it doesn't explain the length.

My complete rantings at Yellow, Creamy and Bittersweet.