During warmer months, St. Paul resident Brad Dettman enthusiastically takes to the metro area's trails and roadways on his bike, cycling about 300 miles a week.

"It's nice to have a dedicated bike pathway to stay out of traffic. It takes the hassle factor out of it," he said, pausing during his morning bike ride on the Midtown Greenway this week.

The internationally known Midtown Greenway plays a big part in his cycling routine — it draws thousands of pedestrians, joggers, dog walkers and others, as well. The 5.5-mile path stretches along a former railroad corridor from west of Bde Maka Ska (formerly Lake Calhoun) and ends — rather abruptly — at W. River Road edging the Mississippi River.

The idea of continuing the Greenway over the existing, lightly used Short Line railroad bridge across the river has alternately enticed and vexed bicycling and pedestrian enthusiasts for years. Now, the Midtown Greenway Coalition, a nonprofit advocacy organization, and 36 other interested groups, have launched a public funding campaign to raise $45,000 to pay for an engineering study.

The study would probe an obvious question: How much will it cost to repair the bridge to make it safe for biking and walking? Once that's determined, the group plans to engage bridge owner Canadian Pacific Railway and government agencies to "get it done," said Soren Jensen, executive director of the Midtown Greenway Coalition.

"Everyone loves this vision and wants to see it happen," Jensen said recently. "It makes so much sense. You're biking along, cruising along, and all of the sudden, the trail stops."

A chain-link fence prevents Greenway users from continuing over the railroad bridge to Prospect Park and St. Paul. Bicyclists and pedestrians must now use bridges at either Franklin Avenue or Lake Street-Marshall Avenue to cross the river.

Extending the Greenway over the Short Line bridge "is the critical linchpin" to continuing the path in St. Paul, said Andy Singer, co-chair of the Saint Paul Bicycle Coalition, which is part of the fundraising effort.

The idea involves using the rail corridor to Cleveland Avenue in St. Paul and ultimately linking to Ayd Mill Road and W. Seventh Street with connections to the new Minnesota United stadium and several of the city's neighborhoods.

"There's no question it would be a huge benefit to the city of St. Paul, it would be phenomenal to connect the cities together," said Reuben Collins, transportation engineer for St. Paul. The Greenway bridge connection is part of the city's long-term bicycle plan, but Collins concedes "we have a lot of [bike] needs across the city, so for now it's a lower priority. We'll wait to see how it shakes out with the bridge."

Andy Cummings, spokesman for bridge owner Canadian Pacific, noted the structure is "an active railway bridge, and sees regular moves of freight trains. While we don't have a formal proposal to respond to, we would have serious concerns about allowing cycling on the bridge."

Jensen said only one train uses the bridge on a daily basis, hauling grain and scrap metal to locations off Hiawatha Avenue. Minnesota Commercial Railway, which operates the trains, did not respond to a request for comment.

Jensen says the study will investigate various options for the bridge, such as whether bikers and pedestrians could share the structure, or if it's possible to build a new bridge atop existing support piers.

A 2006 study commissioned by Hennepin County explored ways to extend the Greenway over the Mississippi River, including new bridges to the north and south that would cost up to $14 million. The URS Corp. study did not recommend using the current bridge, which was built in the 1880s, due to "significant cost" and the age of the bridge.

For a while in 2007, Hennepin County pursued a new bridge, but met with cost pressures and deep resistance from the Friends of the Mississippi advocacy group, the National Park Service, Canadian Pacific and others.

Peter McLaughlin, chair of the Hennepin County Regional Railroad Authority, said the Short Line bridge would provide the Greenway with a "great connection. But it's complicated and potentially expensive."

Regarding the impending study by the Greenway Coalition, McLaughlin said, "I'm always up for new information," adding that he contributed $30 to the campaign.

Yet Greenway enthusiasts remain undeterred. They point out that the Northern Pacific Bridge No. 9, which was built in 1924 and crosses the Mississippi between Seven Corners and the University of Minnesota, was opened to bicycles and pedestrians in 1999.

Plus, they say, new technology, such as drones, is available to better assess the bridge's structural underpinnings, especially since it's unlikely Canadian Pacific will permit access to the bridge for the study.

As of Friday, the campaign had raised $12,243, not including a $10,000 anonymous matching grant from a Minneapolis donor. Additional funds raised by May 5 will support work on the proposed St. Paul Greenway and the Min Hi Line, a proposed bike-pedestrian trail between the Greenway and Minnehaha Falls.

"We could keep waiting and do nothing," Jensen said. "Or we could try to be proactive and get some momentum going."