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Positively Fourth Street; MnDOT plan could mean big changes for busy NW Austin intersection

Fourth Street Northwest off Interstate 90 is one of the busiest intersections in Austin, and, for many, it’s the primary gateway to the city. But that intersection and its on- and off-ramps are going to be rebuilt and restructured — eventually.

Officials with the Minnesota Department of Transportation and engineering firm SEH updated the Austin City Council earlier this week on a long-range plan to replace or rehabilitate 10 Interstate 90 bridges from West Oakland Avenue to 28th Street Northeast through Austin.

“They’re really starting to show their age and they’re coming to the end of their useful service life,” said Jai Kalsy, principal project manger for MnDOT District 6 in Rochester.

The biggest pending changes are for Fourth Street Northwest, where an estimated $9 to $10 million project would replace the bridge and restructure the on- and off-ramps to be rebuilt to all lineup.

But all of the other I-90 bridges through Austin are being discussed — except for the 11th Place Northeast bridge being replaced this year — with costs ranging from $800,000 to a few million dollars.

MnDOT kicked off the process with community stakeholders back in 2015 to form a plan for Austin’s I-90 bridges, most of which were built in the 1950s and 1960s.

The plan looks at the corridor as a whole and not just individual bridges, aiming to take a comprehensive look at the corridor.

Kalsy described the study as a 10-year investment plan. Of the 10 bridges on the list, three are funded for 2021 and the rest are on the long-range plan but not yet funded.

Due to funding challenges, MnDOT is planning a combination of replacement projects and rehabilitation projects, according to Chris Hiniker of SEH.

The bridges

The bridges being discussed, from west to east, are:

•Highway 105 / West Oakland Avenue: MnDOT is recommending to rehabilitate this bridge since it’s in reasonable condition, and there aren’t serious concerns with safety or traffic issues. The railing and deck will be replaced, and about three feet or so will be added to widen sidewalks and bike lanes along the road.

•14th Street Northwest or 218 North: Rehabilitation is also recommended for this bridge, and it will include a new deck with a bit more space, especially on the southbound bridge, for walkers or bikers. There’s potential to expand the sidewalk to about 6 feet on the south side.

An 8-foot raised sidewalk is on the northbound side, and MnDOT could widen that to 10 feet.

On the eastbound I-90 offramp, MnDOT is looking to provide left and right turn lanes to keep traffic moving more steadily and not backing up on the ramp.

•Fourth Street Northwest / County State Aid Highway 45: The Fourth Street Northwest bridge is in the heart of Austin near the 18th Avenue Northwest retail corridor, and MnDOT leaders called a key hub for reaching downtown Austin.

“It’s the gateway to the community,” Hiniker said.

It’s also a very complicated intersection. Hiniker described the ramp exchange as unique, noting there’s not a great traffic flow with the staggered on and off ramps at the stoplight for westbound I-90 traffic.

To compound the issue, the space to work with is constrained with Oak Cemetery on the northeast corner of the intersection.

“MnDOT clearly recognizes this as a major challenge, this location,” Hiniker said.

“From our traffic analysis, it showed this was the area of greatest challenge for operations and safety,” he added.

MnDOT is currently thinking of a compressed diamond interchange, which means the ramps would be closer together than a standard configuration. That would reconfigure the lanes to line up more directly, largely by pulling the westbound on-ramp close to the interstate to line up with the westbound off-ramp. The eastbound ramps would also undergo some adjustments.

The bridge will be two lanes in both directions with left turn lanes and plans for 6- to 10-foot trails on both sides of the bridge.

•Interstate 90 bridges over the Cedar River: These bridges will need to be replaced, according to Hiniker.

During construction, traffic will likely be reduced to one lane in each direction with one bridge open and the other closed for construction.

Preferably, MnDOT would complete this project at the same time as one of the other nearby bridge projects, like work on the Sixth Street Northeast bridge. That would keep the switch over to one lane through multiple projects. However, that will make for a larger overall price tag for that construction season.

•Sixth Street Northeast: This bridge is pegged for rehabilitation since it’s in good condition, but some concerns include sight lines underneath the bridge for oncoming traffic. However, the area doesn’t show a substantial crash problem because it has slow traffic and most people using the roads use it every day.

The aim is for clearer lines of sight around the bridges.

•Both 21st Street Northeast / Highway 218 and 28th Street Northeast: Since these two bridges are about a half-mile apart — well below the standard of today’s design — the initial plan was to investigate ways to connect the interchanges via frontage roads. However, that was quickly shelved since the proximity to Austin Municipal Airport greatly limits construction of new roads based on Federal Aviation Administration standards.

Instead, the plan is to replace both bridges with improved accommodations with 6 to 10-foot trails. On the 21st Street bridge, that’d connect neighborhood sidewalks and trails to the trail system of and near the Jay C. Hormel Nature Center. The Shooting Star Trail is slated to connect with Austin at the 28th Street bridge.

Time frame

In 2021, MnDOT has funding for the 28th Street Northeast bridge and rehabilitation for the 14th Street Northeast bridges. MnDOT is working on a funding package for some of the remaining bridges, but it’s difficult to say as funding is in flux right now.

However, Greg Paulson, assistant district engineer for program delivery in MnDOT District 6 in Rochester, spoke of a four-year state transportation improvement program. However, these bridges fall more on a six- to 10-year timeframe.

But the leaders said the study positions Austin well for funding moving forward.