The Atlanta BeltLine is considered to be among the most ambitious transportation projects in America.

Originally thought up by architect Ryan Gravel in 1999 - he was then a graduate student at Georgia Tech - the BeltLine is transforming old railroad corridors that surround Atlanta's downtown into acres of public park space, walking paths, biking trails and light rail.

Now the key is getting people in the car-crazy city to actually use it.

Enter Dan Popovic. The PreventObesity.net Leader is the creator of the Atlanta BeltLine Running Series, which sponsors a series of road races designed to introduce people to the BeltLine while simultaneously helping city denizens become more physically active.

"Atlanta is full of drivers, but Atlanta is also one of the top running communities in the country," Popovic says. "People are running a lot. They want these safer elements, an environment where they can interact with people and where they don't have to fight with cars and traffic lights."

But the series isn't just about the races. Popovic also created the Atlanta BeltLine Running Series Community, an interactive online network that allows runners to earn points for participating in races, compare their times with other runners and earn cool prizes in the process.

The idea is to create a community of people who not only enjoy running, but also want to meet their neighbors and bring a sense of camaraderie to the BeltLine.

"This isn't just a typical road race," Popovic says. "It's more of a product, it's community involvement, it's connecting with people, it's creating interactions and it's rewarding... accomplishments."

The running series first launched in April 2011 with a 5K race that included about 350 participants, Popovic says. Word quickly spread about the series, and the final race in 2011 featured 900 participants.

Popovic and his fellow running series organizers next worked to get the entire city involved by hosting challenges, in which different teams competed on the course for bragging rights. In one race, the Atlanta police and fire departments competed against one another; in another, local media personalities hit the pavement.

In December, the series sponsored a 10K race that saw various college alumni clubs forming teams to compete for a happy hour prize. About a dozen teams took part in the event, which was held the same day as college football's Southeastern Conference championship game and featured schools setting up tailgate sites along the route.

In another event, city neighborhoods competed in three categories to see who could recruit the most runners, who was the fastest and who had the most spirit. The city's Old Fourth Ward neighborhood swept the competition.

"The neighborhood took the cash prize and they used it for improvements to their community," Popovic says. "We thought, this is working. This is what we wanted you to be doing."

The running series is scheduled to host its first race of 2013 in April. In the meantime, Popovic hopes to bring young people to the BeltLine for running events, and is working to create similar initiatives in other cities. He also is working with Atlanta's public transit agency to build a technology system that rewards people for taking public transit.

Popovic says the running series is expected to grow this year, attracting new runners and introducing more Atlanta residents to the BeltLine.

"It really opens up our audience to people who don't really know anything about the Atlanta BeltLine," Popovic says. "We've got an active community already, and this really gets that community into a better environment... it's getting people out of their cars, out on a trail and rewarding them for their accomplishments."