MARATHON -- Retired truck driver Norm “Runaway Grandpa” Dille arrived at the old Seven Mile Bridge for his daily ritual. He walked about half a mile roundtrip before plunking down in a green plastic chair to gaze at nature’s beauty and at Henry Flagler’s century-old engineering marvel.

“I love it,” the 71-year-old from Ohio said on a breezy morning last week. “I love the view, the colors, the story behind it with the railroads. And, when I was young, I used to bring my kids down here. I remember the old bridge before the new one was built.”

Runaway Grandpa is among thousands of people who walk, jog, push strollers, bike, picnic, catch the sunrise, toast the sunset and watch for marine life on the world famous bridge, once called the Eighth Wonder of the World and now on the National Register of Historic Places.

How much longer can the bridge’s main 2.2-mile section safely support people? Nobody knows. The steel and concrete bridge, completed exactly 100 years ago to link Marathon to the Lower Keys, is deteriorating in the harsh salt and sun environment. The main section — which goes to historic Pigeon Key, a tiny island that once served as the work camp for the Florida East Coast Railway — already is too unsafe for vehicles and fishermen who continuously lean on the fragile railing.

Last summer, a nonprofit community group called “Friends of Old Seven” was formed to try to rescue the bridge. Leading the charge is Bernard Spinrad, a retired Marathon resident who formerly was Aruba’s director of tourism.

Friends of Old Seven is working with Monroe County, the city of Marathon and the bridge owners (the Florida Department of Transportation) to come up with a bold but practical renovation plan — and the $16 to $20 million needed to fund it.

All sides agree it is in everybody’s longterm interest to save the bridge — which is a major tourist attraction to the Middle Keys but has been “a bridge to nowhere” to FDOT since 1982, when the new Seven Mile Bridge was completed.

“We’ve been trying to give up the old bridge’s ownership for decades,” said Gus Pego, FDOT’s District 6 Secretary. “It’s a recreational facility, not a transportation facility. … And what I tell commissioners and folks who ask me: ‘Given our limited budget, wouldn’t you rather we maintain the new bridge?’ ”

The unique old bridge has generated plenty of free publicity for the Middle Keys. Kisha and Jen pedaled three-wheeled bikes along the bridge to win CBS’ Amazing Race 18. Cuban migrants were found clinging to piling of the old bridge in 2006 that led to a controversial “wet foot/dry foot” case that sent them back to Cuba. And in 1994, the old bridge was famously blown up in True Lies with Jamie Lee Curtis and Arnold Schwarzenegger.

Pego said the parking lot at the entrance to the north end is concrete now thanks to the True Lies crew, which needed a hard surface to launch the U.S. Marine Harriers.

Spinrad said the old Seven Mile Bridge has the potential to boost the local economy even more. He’s been inspired by the cases of two other abandoned railroads that were brought to life by public and private partnerships: the High Line in New York City and Walkway Over the Hudson in upper New York.