On a hunch, Marion Collins took a giant tape measure last December and calculated the distance between light-rail and freight-rail tracks installed near her Minneapolis home for the Southwest light-rail line. Her hunch proved correct — and it turned into the latest problem dogging construction of the $2.9 billion transit project.

Collins knew the distance between the center of one set of tracks to the middle of the other was designed to be 25 feet to separate light-rail and freight trains along a narrow stretch of the route. But her measurement found the distance was nearly 11 inches short of the mark.

That means the 200 light-rail trains traveling through the Kenilworth corridor every day will be nearly a foot closer to nearby freight trains, which often carry hazardous materials such as ethanol. The project, about 80% complete, is slated to begin service in 2027.

"When there's a collision, our neighborhood will become a big black hole," Collins said in a recent interview. Other neighbors, donning tape measures and a healthy sense of skepticism, came up with similar measurements as well.

Video (00:37) Minneapolis resident Marion Collins measures the distance between freight and light rail tracks in the Kenilworth corridor.

In an interview with the Star Tribune, Southwest Project Director Jim Alexander said, "we have to figure out what happened and see what we can do about it." He told members of the Metropolitan Council last month, after KSTP first reported the problem, that the fix could happen later this spring or early summer and it won't affect the project's overall price tag.

Alexander said his staff took their own measurements near the W. 21st Street station and found the tracks are seven inches short of 25 feet. Either way, the tracks were installed too close to one another.

The co-location of light-rail and freight trains in the narrow corridor of Minneapolis has long been a challenge for the 14.5-mile extension of the Green Line, which will link downtown Minneapolis with Eden Prairie. An early design of the route called for freight trains, operated by Twin Cities & Western Railroad (TC&W), to be routed through St. Louis Park, leaving the Kenilworth corridor with just light-rail trains, and a bike and pedestrian path.

But St. Louis Park residents fended off the proposed alignment a decade ago, leaving transit planners to figure out how to squeeze freight, light rail and the bike and pedestrian path in Minneapolis. This led to a tunnel being added on part of the route for light-rail trains, a complex option that caused the project's budget to more than double since 2011, making it the most-expensive public works project in Minnesota history.

Alexander said about 100 feet of track, which was installed around a year ago, is affected. The segment of the project in Minneapolis, he added, hasn't been formally turned over by the contractor to the Met Council, which is overseeing Southwest's construction. When that happens, then the project's engineers check to see if it was built to specification.

"We're talking to our engineer to see what happened to see what we can do about it," Alexander said. "I don't consider this a big issue, but we have to take a look at it and see what we can do to fix it."

The project's general contractor, Lunda/C.S. McCrossan Joint Venture (LMJV), declined to comment on the track issue.

The Southwest project is currently being investigated by the state's Office of the Legislative Auditor in an attempt to figure out what went wrong with its ballooning budget and timeline. One of the reports issued by the auditor last year took the Met Council to task failing to enforce the $799 million construction contract, but LMJV later criticized the state auditor for lacking the necessary expertise to review such a complicated project.

The Federal Transit Administration, which regulates light rail and is paying nearly $1 billion to build Southwest, referred questions to the Federal Railroad Administration (FRA). A spokesman for the FRA said there is no "specific guidance" on track spacing, crash walls or barriers in this kind of scenario.

Alexander said anything less than 25 feet between freight and light-rail tracks would require a crash wall, according to the project's design. The project's design calls for several crash walls, including one just west of Target Field that was built at the behest of rail giant BNSF Railway to separate its trains from Southwest's. The mile-long wall cost $93 million.

Mark Wegner, CEO of TC&W Railroad, said the discovery about the track spacing "isn't a concern, they can rectify it." If tracks were closer than 25 feet, it would make it more difficult and expensive for maintenance workers to do their job safely, he said.

"I would characterize this as a potential annoyance," Wegner said. "It's not a safety concern."

Alexander said the current design calls for "intrusion protection" — bolsters separating freight and light-rail trains along this segment that send a signal to a rail control center and alerting train operators if there's a problem.

Even at 25 feet, Collins says it's too close for comfort. "I really don't feel they're invested in safety," she said of the Met Council.

The Southwest project has been controversial in Minneapolis for more than a decade, and in 2014, neighbors sued to stop the line from being built, saying it violated federal environmental laws. The suit was unsuccessful, but bitter feelings continue to fester.

Not far from the track blunder, residents of the Cedar Isles Condominiums are locked in mediation with the Met Council over cracks in the building and flooding in its parking garage that occurred during construction of the nearby Kenilworth tunnel.

When asked why it took residents donning a measuring tape to discover the latest problem, Alexander said "I know this has caused another ripple with the neighbors, but we still feel very highly about this project, it will be a transformational line for the region."

Collins says she's glad she acted on her hunch: "I don't trust them, that's why I measured."