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UDOT wants to make US 89 a freeway from I-15 to I-84

Started by Kniwt, August 24, 2017, 07:16:42 PM

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Quote from: US 89 on May 17, 2021, 06:54:46 PM
Finally tracked down the agenda item for the $60m addition from last month's transportation commission meeting: (rather large PDF - pages 1-2)

QuoteThe original scope for the US-89 project stopped short of the I-84 interchange due to funding constraints. The public has been very vocal about concerns of current and future traffic backup at the interchange at I-84. In response to the concerns, UDOT has done additional traffic analysis and has confirmed that the traffic can back up for more than a mile on Northbound US-89 during the PM peak and add
more than 5 minutes of delay to commuters. This delay is only anticipated to increase with the completion of the US-89 reconstruct project.

The additional scope proposes to add a new SPUI (Single Point Urban Interchange) at the I-84 / US-89 junction. New on and off ramps will be built to provide better sight distance, standard deceleration and acceleration lengths and improved storage. The bridge on I-84 over the Weber River will also be reconstructed as part of this project.

So it appears they are indeed converting the existing partial cloverleaf to a SPUI. Personally not a fan of that, but the geometry on some of those existing ramps does suck (particularly the ramp onto westbound 84) and definitely could use some improvement.

Unless there was a concurrent project to increase capacity on I-84, especially west toward I-15 and Ogden, configuring the northern terminus of the US 89 project with a SPUI instead of a free-flow interchange would make sense to regulate the flow of NB traffic onto WB 84.  Otherwise the segment of 84 west of the interchange would likely become a chokepoint, particularly during commute hours.  Not so much with the opposite traffic movement unless the RH turn onto US 89 was itself signal-regulated. 

US 89

Took the opportunity to drive through the project area recently (and realized I never posted my pictures from back in January). As of now, 89 is now a free-flowing road from the I-84 interchange signals all the way down through Farmington, and the southernmost three interchanges (200 North, Oak Hills, Gordon) are all open. It appears all direct access to side streets has now been closed - and that currently includes Antelope Drive, whose interchange will be completed probably next year sometime. No new permanent signage yet, so no new exit numbers so far.

Work appears to be substantially complete at the three open interchanges, other than the ultimate restriping to 3 through lanes which will probably wait until the whole project is complete. The bridge design that the public voted on wound up looking like this:

The latest project update email also contained some interesting information about a temporary bridge that will carry US 89 over the Weber River while the permanent bridges are being rehabilitated:

QuoteAt the far northern end of the project, work is moving forward to replace the support beams and driving surfaces on the two bridges over the Weber River. In order to keep all lanes open in both directions while we do this work, our project team has rented a temporary steel bridge that has been assembled on-site and then pushed into place over the river.

Crews plan to shift northbound traffic onto this bridge as early as May 26, with a southbound shift planned after the Memorial Day holiday. Drivers should be prepared for a new traffic configuration in the area.

The temporary bridge is 210 feet long, 45 feet wide and weighs approximately 500,000 lbs. It will be in place until late fall, when traffic is scheduled to shift back onto the permanent US-89 bridges. This same bridge has been recently used on another UDOT project that replaced two I-80 bridges west of the SR-201 interchange near Saltair. In addition to providing temporary detours during construction, these bridges are also used to restore critical routes during emergencies (like floods or hurricanes), and by military forces – some models are sturdy enough to accommodate tanks and other armored vehicles.

Also, the environmental study process for the I-84/US 89 interchange has officially begun. It's currently in a pre-environmental stage where they're collecting data on existing traffic conditions and feedback from affected cities. That's supposed to last through this August, with the formal environmental study process to follow. That is a separate project from the 89 freeway upgrade and has its own website (


Oh neat, a Bailey bridge. You don't see those in the US too often. (They're mostly used for military applications, or in lower-income countries that cannot afford a more permanent crossing.)
uncontrollable freak sardine salad chef


Quote from: Scott5114 on May 21, 2022, 09:58:21 PM
Oh neat, a Bailey bridge. You don't see those in the US too often. (They're mostly used for military applications, or in lower-income countries that cannot afford a more permanent crossing.)

I've seen them used a few times in Washington, notably as an emergency fix when the I-5 Skagit River bridge collapsed back in 2013, but also for more normal bridge replacements or repair like this one here in Utah.

Example on I-90 in Cle Elum, WA from 2019 (looks like streeview car went through as they were putting in the approaches for it):

Plutonic Panda


Don't they have one at the PA Turnpike and PA18, it's been temporary for like 10 years.

US 89

At long last, this project is done. Apparently it was the biggest project undertaken by UDOT since the I-15 CORE (Utah County reconstruction) project wrapped up in 2012. Which seems kind of surprising - I'd have thought the I-15 Point of the Mountain and south Davis County reconstructions would be more, but apparently not. Either way, a long needed project is finally complete.

Unfortunately, this will now leave a pretty significant bottleneck where the freeway now ends just before the I-84 interchange. Facebook group suggests this is because Weber County had no interest in spending any money there right now but who knows how accurate that is. As far as I know, no free-flow upgrade to this interchange is in the cards for the foreseeable future. At some point soon (perhaps already?) the outdated parclo design is planned to be reconfigured into a SPUI with I-84 passing over US 89.


^ A SPUI at 84/89 is considered a "short term solution".  UDOT is looking into the longer term with a current study.

Plutonic Panda

It looks like in the long term they will consider a fully directional stack so that is nice.

US 89

Quote from: froggie on August 01, 2023, 09:59:37 AM
^ A SPUI at 84/89 is considered a "short term solution".  UDOT is looking into the longer term with a current study.

But even so, the SPUI will be better than the current state of affairs. Would have been nice if it could have been included with the Davis County freeway project instead of having an upgraded, longer US 89 freeway still dumping directly into the outdated parclo that's there now.

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