Bridge decks have been placed for two of the three railroad bridges in the SE Main/20/21st Street underpass project. Much of the year was spent finding solutions to challenging soil conditions. (Photo/Cody Hedstrom, Northern Drone)
Nancy Edmonds Hanson
After spending the first half of the year “looking for a way forward,” assistant city engineer Tom Trowbridge says the mammoth SE Main/20/21st Street railroad underpass project is back on track and likely to open by this time next year.
“Everything about this project has been kind of unusual,” he observed last week. “But the good news is that the project is moving forward again. After a lot of research, review and discussions, everybody – the city, BNSF Railway, engineers, the contractor – are making sure we’ll have a safe public infrastructure.”
He added, “Everyone is going to be happy when this project is done.”
From the start, the $51 million project has thwarted the city’s expectations of swift completion. Twenty years of planning, lobbying and negotiations went into the railroad safety project, designed to untangle the snarl of three major streets and three railroad lines that had been deemed the most unsafe intersection in the city. The future looked bright three years ago. But when construction bids were opened at last in April 2018, they came in higher than expected, and the start was delayed.
A $6 million appropriation by the legislature got the project back on track, but that meant construction contracts couldn’t be awarded until June. Ames Construction finally began work in July.
“We hoped to have it all complete in the fall of 2019,” Trowbridge said. But bad weather slowed down the progress. Then, in August 2019, the ground went out from out from under the still-optimistic plan – almost literally: While installing sheet piling to hold back the slopes along the 30-foot-deep excavation to carry cars under the railroad bridges, Clay County’s ever-tricky clay soil slumped. A major segment of the project came to a dead halt.
‘Toils on Weak Soils’
This was far from the first time the soils of the area, the bottom of prehistoric Lake Agassiz, have foiled the best-laid plans involving railroad overpasses. Over a century ago, the Northern Pacific Railway decided to solve the problems created by the steep grade between Glyndon and Hawley. Rising from the bottom of the Red River Valley, the slope required extra locomotives to push or pull loaded trains up to the stop.
NP engineers settled on constructing an earthen embankment for a more gradual rise. They selected a 7-mile stretch of the rail route just south of Highway 10 to be raised, creating a more gradual incline. The project, dubbed the Stockwood Fill, was expected to total $2.1 million and be completed in two years.
In April 1906, contractors hauled in more than 2 million board-feet of lumber and millions of cubic yards of dirt fill. But in August, they discovered it was sinking. Geologists investigated the phenomenon; they determined the rails lay atop a bed if unstable glacial sediment, including quicksand, sand and the ubiquitous Clay County clay. The track sagged, then sagged some more. Soon it was too steep for work trains to navigate. Crews continued to dump dirt onto the embankment, only to watch it continue slumping almost before their eyes.
The determined railroad executives pressed on. In Spring 1908 a new superintendent ordered construction of a 3,000-foot permanent bridge over the region. But in May, 850 feet of track sank nearly 50 feet in one week. The base was widened, and work continued. By the next summer, the trestle bridge had been built. Then, in July 1909, the embankment arch itself began to sink … ultimately breaking in the center. It was ultimately swallowed by quicksand.
The NP finally admitted defeat that September, with the project two years behind schedule and $700,000 over budget. Extra locomotives continued to have to boost eastbound trains up toward higher ground for more than 20 years, until more powerful engines were finally introduced in the 1930s.
(This information from he Minnesota Historical Society’s website MNpedia is based on the book Toils on Weak Soils by Donald P. Schwert and Mark E. Peihl.)
Moving Forward
The Moorhead situation is probably not as dire, though excavation sites open to rain always hold the possibility of slumping. Trowbridge explained the issues on 20/21st were related to temporary construction that had to be done before work could begin on the permanent infrastructure, since both BNSF and the Otter Tail Valley Railroad continue to carry southbound trains – the OTR only one per day, the BNSF eight to ten. Meanwhile, though, work could continue on other aspects. Girders have been set in place for the two bridges that span 20th and 21st Streets. The third, which crosses the path of SE Main, is expected to be placed at the end of May. Then the temporary tracks known as “the shoofly” can be removed, making away for more progress on the major intersection.
Trowbridge predicts, “If everything goes according to the current schedule, we’re thinking the traffic portion of the project should be open in September or October or possibly November 2021.” Construction will continue on the railroad right-of-way after that as BNSF finishes its wye – a Y-shaped track that will enable trains to turn southward without inching across downtown Moorhead intersections, pausing, and then backing up to negotiate the turn – but that won’t affect vehicle traffic.
What about the newly funded 11th Street Underpass project? Trowbridge conceded that Clay County clay is down there along that corridor, too. “We expect to have the same soils,” Trowbridge said. “In the Red River Valley, it’s all about what depth you dig down to. There are distinct layers. At 35 feet down (the depth of the underpass), we’ll be getting into some very soft, wet soils.
“The most significant difference is that we now have more experience dealing with these issues,” he continued, citing the partnership on 11th Street between the city and the Minnesota Department of Transportation, which is now leading that project. At the same time, the route from Main to First Avenue North runs across three far busier railroad tracks. The northernmost Prosper line carries 20 to 25 trains a day; the two along the KO line directly north of Main accommodate 50 to 60.
While design work has accelerated since the Legislature appropriated $62 million in October, that aspect is now largely in the hands of MNDOT. The city staff has turned toward acquisition of the adjacent properties. That’s not simple, either. “There’s much more development downtown, and it’s squeezed closer to the tracks than along SE Main/20/21st,” Trowbridge pointed out. “We also expect to have a lot more utility issues.”
It’s too early for predictions of when Moorhead drivers may finally cross under the railroad tracks unimpeded; published estimates set that happy moment in the mid-2020s. In the meantime, though, there’s light at the end of the tunnel (so to speak) for the decades-long quest for safe, unhampered travel through the ever-frustrating entwined intersection of Southeast Main and 20/21st Street.
