I-15 Inkom Bridge - "Bad Shape"

[edwaleni]

https://www.eastidahonews.com/2023/12/many-fear-inkom-i-15-overpass-primed-for-catastrophic-failure-before-expected-2025-replacement/

INKOM — Some 25 Inkom residents gathered at the Inkom Community Bible Church Wednesday night to discuss a bridge.

The bridge in question is an Interstate-15 overpass near town that many residents fear could be doomed for "catastrophic failure" in the very near future.

A quick glance at the bridge is enough to immediately recognize rusted rebar, crumbling concrete and shoddy patching.



According to an Idaho Transportation Department Engineer Manager Eric Staats, the bridge was recognized as having a "high" need for replacement in 2017.

In 2018, ITD switched the bridge from the standard biannual inspection plan to a yearly inspection plan. Around that same time, ITD installed steel beams as a support system for the concrete girders.

Many residents, including Luana Lish who organized the meeting, believe ITD has "kicked the can down the road" long enough when it comes to replacing the "failing bridge."

"The can has been kicked down the road so many times that they're not kicking the can anymore, they're kicking concrete," Lish said.



Staats was present at the meeting, explaining ITD's plan for the bridge to the town's concerned citizens.

As he explained, federal funding for the replacement of six structures — both directions of three different bridges in town — has been approved for 2025.

Asked if there was any possibility the work could be done sooner than that, Staats said there is a plan to use state monies for the work, then replace those funds with federal money in 2025. However, funding is not the only issue — planning and design has still not been completed for the work.

Staats stood before the Inkom residents for more than an hour, fielding questions — the majority of which had to do with the department's plans.

Residents asked why it has taken so long to move toward replacing the bridge; they questioned why the "Flying Y" reconstruction wasn't delayed until after the bridge was replaced; and they asked if there was any contingency plan should the condition of the bridge worsen.

Residents also took the opportunity to raise other concerns.

One woman asked if it was at all possible for the speed limit on I-15 through Inkom to be lowered from 80 mph to 65 mph, like it is through Pocatello. Another resident asked Staats if ITD could add new signage to help visitors find their way back to the I-15 onramp. A third resident addressed the potholes that have developed on the interstate near Inkom, raising concerns regarding damaged vehicles.

"Our little town is really close, and any kind of problem affects us all," Lish told EastIdahoNews.com after the meeting. "This is a huge problem, and this doesn't just affect Inkom, this affects all of southeastern Idaho and anyone who uses the I-15 corridor."

Staats assured the Inkom residents he would take their concerns to ITD management.

"I totally understand the scheduling dilemma that the Idaho Transportation Department has," Inkom Mayor Max Shaffer told EastIdahoNews.com. "But I hope that they understand our concern, too, and that they will move us up if they can."

If ITD is able to move the work up, Staats said the work would not begin until, at the earliest, 2024.

When it does happen, he said, there will be interstate shutdowns for around two years.

Staats believes the plan is for the work to be done on the southbound lanes first, meaning all southbound traffic through the Inkom pass will be diverted to the northbound lanes. When that portion of the work is completed, he said, the northbound lanes will be shut down will all traffic being diverted to the southbound lanes.

"Our structural engineers will evaluate the northbound structure, to make sure there aren't temporary improvements that need to happen to that structure — or any of these structures — in order to have the two-way traffic on it," Staats said.

Following the meeting, Lish said she appreciated the job Staats did, speaking openly with the residents and allowing them to vent their frustrations. However, she added, she is concerned the inspections — as poor as they've shown the bridge's condition to be — have found the extent of the problems.

[edwaleni]

Looking at GSV, it appears both the northbound and southbound bridges suffer from this degradation, both on the west side support beams.

Looking at the pitch of I-15 at this overpass, it is most definitely set to have runoff flow west towards these beams.

But there are no drains or channels to redirect the water here, so it flows downward using gravity through the crack and gaps in the road/bridge joints.

Rainfall and snow melt all flow towards these joints and these support beams.

It looks like this overpass was built in the 1966-67 timeframe.

So if they are replaced in 2025, that would put them close to the 60 year mark.

[CtrlAltDel]

Looking at GSV, it appears both the northbound and southbound bridges suffer from this degradation, both on the west side support beams.

Looking at the pitch of I-15 at this overpass, it is most definitely set to have runoff flow west towards these beams.

But there are no drains or channels to redirect the water here, so it flows downward using gravity through the crack and gaps in the road/bridge joints.

Rainfall and snow melt all flow towards these joints and these support beams.

I think you might be right.

[edwaleni]

https://www.eastidahonews.com/2023/12/follow-up-inspection-completed-on-inkom-bridge-next-full-inspection-scheduled-for-summer/

'Follow-up' inspection completed on Inkom bridge; next full inspection scheduled for summer



INKOM — The latest Idaho Transportation Department inspection of the Inkom Interstate 15 overpass bridge shows "no changes."

According to ITD District 5 spokesman Justin Smith, a Dec. 18 inspection of the bridge reported no changes to the state of the structure, which many Inkom residents fear is due for "catastrophic failure."

Smith told EastIdahoNews.com, that the most recent inspection of the bridge was not a "full inspection," but what he referred to as a "follow-up" inspection to monitor the status of the bridge.

"We just wanted to, kind of, go with the extra step — to make sure there wasn't anything more that we had to worry about from previous inspections," Smith said.

ITD Engineer Manager Eric Staats told Inkom residents during a Dec. 8 city meeting that bridges and overpasses are inspected every other year, until a time the bridge's status is deemed concerning. At that time, the bridge is placed on an annual inspection schedule, with the possibility of it being inspected multiple times a year.

According to the ITD website, the Inkom bridges, built in 1962 and 1963, have shown "signs of wear" since 2017. That same year, they were designated in need of replacement.

However, the earliest those replacements will come is 2025, Staats said.

One question Staats was not able to answer at the Dec. 8 meeting had to do with the extent of the inspection. He was asked more than once if any type of ground penetrating radar or similar technology was used during the annual — and now biannual — inspections and was unable to provide an answer.

The concern voiced by many in attendance at the meeting was the rust shown on the exposed rebar. If the rust travels into the interior of the structure, several residents pointed out, it would cause serious concerns.

According to Smith, inspections are done visually. However, some tests can be done to determine if there are any structural concerns not visible on the surface.

The next "full inspection" of the bridge is scheduled for September, Smith said.

[vdeane]

Those temporary supports do not appear to be ADA compliant with respect to the sidewalk they intrude on.

Regarding the residents wanting a speed limit reduction on I-15 - why?  It would appear that the reason for 65 in Pocatello is due to the concentration of interchanges in the area and presumptive use by local traffic, which isn't the case with Inkom.

[The Ghostbuster]

Are the bridges at Exits 57 and 58 also planned to be replaced, and the ramps reconstructed, even if they aren't in as bad of shape as the Main St. bridges?

[Taters]

https://itdprojects.idaho.gov/pages/i15-inkom-corridor

ITD plans to reconstruct 9 bridges in the area with construction beginning in 2025. These include 8 on I-15 and 1 bridge on I-15BL through the town.

It appears that traffic will be redirected onto I-15BL during construction on the main interstate, which they are hoping to complete in around 2 years. ITD page above has more information.

[The Ghostbuster]

With the removal of the Exit 57 northbound off-ramp, and moving it to Exit 58, there's no reason for Inkom's Business 15 to remain in existence. Once the proposed construction projects are completed, I expect Business 15 to be decommissioned, unless they want to extend Inkom's Business 15 along to connect with McCammon's and Pocatello's Business 15's via Old Hwy. 91.

[Taters]

I believe a few years back during the planning process, that ITD had decided to leave the interchanges as they are right now, following feedback from the community of Inkom. The business loop should stay as-is.