The Mural Arts Program has brought in a German artist to turn a 5-mile railway corridor in North Philadelphia into a moving abstract field.

The murals will not move. You will.

The Amtrak railway between 30th Street Station and North Philadelphia Station runs through an industrial landscape that has seen better days. Canyons of abandoned factories and warehouses are broken up by hardscrabble landscaping and trash.

For people traveling from New York to Philadelphia, this is that gateway to the City of Brotherly Love.

"I've worked for four mayors, and I'd say every mayor has had staff that have approached me about this corridor," said Jane Golden, director of the Mural Arts Program. "I admit I am someone who is drawn to buildings that are historic -- the older, industrial buildings, anyway. I like to think about Philadelphia during the time of its industrial heyday and the post-industrial landscape that is Philadelphia today."

Golden brought in Berlin-based artist Katharina Grosse to create "psychylustro," seven abstract murals in selected sites along the rail corridor. Some of the painted surfaces will be the imposing stone walls of empty factories; others will be the railbed retaining walls that have become showcases for graffiti artists. And some of the surfaces will be whatever trees, foliage, dirt, weeds, and trash appear between the tracks and Amtrak's security fence.

Using high-pressure spray equipment and thousands of gallons of biodegradable paint, Grosse indiscriminately lays vibrant, fluorescent color over the entire vista.

"Color can be anywhere. It has not a ground where it can stay and may not trespass," said Grosse. "In this way, I can break up hierarchies. A big object and a small object become one because the paint unified them."

The primary viewers for the work will be passengers on the Amtrak and SEPTA trains using the tracks. The 5-mile stretch takes seven to nine minutes to travel, sometimes at high speeds so that psychylustro will appear in a Day-Glo flash to train riders gazing out the window of the car. They will have little time to study the work in detail.

The Mural Arts Project has created more than 3,000 murals in Philadelphia, many of them based on stories and people from the neighborhood where the mural is painted. They tend to be narrative murals, with clearly defined messages and characters.

The psychylustro project has none of that. Grosse is interested in formal questions about the effect of paint on surface, particularly how liquid paint reacts to solid objects.

The way Grosse applies paint – with a spray gun that pays no attention to where the land ends and the building begins – introduces fluidity to a landscape that has been moribund for decades.

"It's about the contrast – the paradox of things that don't normally exist together," said Grosse. "It's mostly about an astonishing encounter with a painting and its surface."