Typically the left side of an escalator dedicated to speedy individuals who don't have the time or patience to let the escalator take them where they need to go, therefore, they angrily speed-hop (sometimes taking double steps) up or down the moving staircase and pass everyone on the right side, leaving them with the following possible impressions:
"I'm more important than you; shove it"
"I'm wearing a suit and have places to be"
"Oh shit I'm late I'm late I'm late"
"I have to catch a bus, get out of my way or I'll trip you"
You can use this method to your advantage, but if you fall on your ass and go tumbling down the moving stairs, you're on your own.
Stacy totally just fell down the escalator express lane! She was moving too fast for her own good.
What!? Is she okay?
She'll be fine. She was on her ass but fortunately still moving upwards.