More people are boarding the area bus service, but the trend must continue to help the region grow, reduce traffic and lessen pollution, officials said Tuesday.

"Bigger and better roads isn't always the answer," said Elliott Summey, chairman of the Charleston Area Regional Transportation Authority. "If we are going to take that next step forward, it's going to have to be mass transit."

Summey called for a "true partnership" between the business community and CARTA that will help spur new jobs and a better quality of life. Flourishing mass transit is a key to recruiting companies, he said.

A contest unveiled in a lot at the CARTA maintenance facility on Leeds Avenue is intended to spur a deeper relationship between private enterprise and local mass transit.

"It's a challenge. It's a dare," said North Charleston Mayor Pro-Tem Michael Brown.

The business that purchases the most CARTA passes with the greatest percentage of employee participation by Feb. 29 will win free advertising on select buses.

Charleston Mayor Joe Riley and College of Charleston President George Benson support the effort. Riley said 10 percent of city employees get to work for free on CARTA.

Benson said the college has been able to relocate 20 percent of its parking permit holders to the vicinity of the S.C. Aquarium because of the free downtown area shuttle. "CARTA makes life better for all of us," he said.

About 500 Medical University of South Carolina employees use the CARTA express bus service to get to work, said Stewart Mixon, the school's chief operations officer.

CARTA has about 7,000 bus passengers daily. Riders in 2011 were up 5 percent, which means 4.3 million people took the bus. Last year, use of the free downtown area shuttle service doubled to about 80,000 monthly passengers, said Christine Wilkinson, CARTA executive director.

"That kind of clearly illustrates what free mass transit can do," she said.