The subway keeps straphangers moving around the clock, but it's the actual motion of the trains that powers one man's artwork. Transit Reporter Jose Martinez introduces us to him.

From the bus, and into the subway, for Lev Ari, it is more than a commute — it's artistic inspiration.

He's turned the subway into his own art studio. Riding every day from Kew Gardens, Queens to Lower Manhattan, he draws intricate shapes and faces that he says are shaped entirely by the train's movements.

"I calm it down as much as I can, listen to the sounds, all the flashing of light, whatever," Ari said. "And then the hand comes down. And just does this dance, which I can't explain."

He calls the process "primaaling" — creating images that reveal themselves differently, depending on the angle from which they are viewed.

"I love it when there's a curve, and the gravity kind of throws me back or pulls me," Ari said.

The artist, who goes by the name Lionheart, says fellow straphangers will take more than a peek at his sketchpad, curious about what he's up to.

"People sitting next to me will kind of glance and see," he said. "And if they're up to it, they will start a conversation. What is it? Why is it?"

Ari was born in South Africa but now calls Israel home. He's in the city to participate in an artists' residency on Governors Island.

He's completed 15 drawings on the subway, all while riding on crowded E trains.

"When I'm doing it, I can't be standing up," he said. "I need at least the stability of sitting. But if I stand, I stand until there's a clear seat."

And he's that rare subway rider who actually appreciates hearing this:

"We are delayed because of train traffic ahead of us."

Those delays allow him to add some very delicate strokes to his subway sketches.

Lionheart will be in the city through the end of the month, after which he'll get back to doing his transit-driven artwork on buses in Israel.