Martin Keil and Henrick Mayer have returned to Europe, having completed their assignment of creating art installations for the Central Ohio Transit Authority.

Martin Keil and Henrick Mayer have returned to Europe, having completed their assignment of creating art installations for the Central Ohio Transit Authority.

But they say the real part of their mission has just begun.

Through the end of August, bus commuters will have the opportunity to weigh on in a variety of subjects facing COTA.

Participants can share their thoughts at the website facebook.com.columbuspublicart 2012.

Keil and Mayer, both natives of Germany, were in Columbus earlier this year, riding the bus, talking to passengers and participating in a workshop to get a better feel for their art, designed to provoke discussion about social issues in an urban setting.

For example, they have named 35 routes, mostly downtown and in surrounding areas, but invite people to rename the routes and expand that objective throughout the city.

They pose the question to riders: What would you call your bus line that leads your city to the future?

"I think it goes beyond art," Keil said. "It's really an open process."

Their work can be spotted on 30 bus stop signs, 80 buses and 11 downtown bus shelters.

The artists' collaborative is called Reinigungsgeselleschaft, considered to be an "artistic venture at the point of intersection between art and society."

The goal is to spur community thought and discussion about creating sustainable options in and around the city, the artists said.

Keil and Mayer first arrived in Columbus 10 years ago as part of a sister-city exchange program and again in 2009 when they did a residency at the Columbus College of Art and Design.

Finding Time: Columbus Public Art 2012, an organization that's part of the city's bicentennial celebration, donated $15,000 toward the current art project. COTA contributed $10,000 for materials and production.

"One of our objectives is to show as broadly as possible a range of what contemporary public art includes," said Malcolm Cochran, program director for Finding Time.

"I think many people think public art is a sculpture or murals," Cochran said.

COTA has a fleet of 300 buses and averages 65,000 passenger trips a day, meaning customers have about a 30-percent chance of boarding one of the 80 buses with art circulating the system, said Beth Berkemer, spokeswoman for the transit authority.

"Around 35,000 customers make up our total boardings each day and that is potentially exposing over 11,500 passengers to the art project on the buses alone," Berkemer said.

"Even more will cross paths with the project at bus stops and passenger shelters."