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[afguy]

A new proposal calls for flipping the configuration so I-75 bridges travel over I-69. Currently, I-69 travels over I-75 at the interchange.

MDOT has been studying the interchange and the I-75 corridor from Court Street in Flint Township to the U.S. 23 split in Mundy Township for ways to improve traffic flow and safety.

RELATED: MDOT exploring options to upgrade I-75 and I-69 interchange

Officials will discuss and receive feedback on MDOT's preferred design option for changes to the I-75 and I-69 interchange and other interchanges along the stretch, including Miller Road, during a meeting in December.

https://www.abc12.com/content/news/MDOT-discussing-plans-to-flip-I-75-and-I-69-interchange-565434521.html

[DJStephens]

Don't know specifics of particular traffic patterns in this area, but perhaps bridge lifespans are nearing end due to de-icing chemicals may be a part of this discussion.   Bearing seats, rockers, and girders themselves.   Non epoxy coated reinforcement in pier caps, piers, and bridge decks also?   
Are some of the pavements seen in the video the original longitudinal concrete slabs?  Pretty amazing if so - that is fifty plus years in a very harsh climate.   

[The Ghostbuster]

I've never heard of a proposal like this before. Has this ever been tried anywhere else in the country that anyone knows about?

[GaryV]

Maybe they want to make I-75 4 thru lanes each way, which they can't do because of the RR overpass?

[tradephoric]

The EB I-69 to SB I-75 movement does have one of the worst merges of any major interchange in Michigan.  It just dumps you onto I-75 without an acceleration lane because it's got to funnel back down to 3 lanes before the RR overpass.  That would be nice not to deal with anymore.

[afguy]

The process began in 2018 when officials researched different options for the interchange and now, a preferred alternative as emerged.

"Using collector distributor routes on both northbound and southbound I-75 to handle all the ramp traffic," said MDOT engineer Trevor Block.

He said officials took into account the public's concerns about the interchange, which included problems with congestion on the highways and merging to come up with the alternative.

The preferred alternative would allow for seamless traffic and two dedicated lanes to handle the ramp traffic on I-75 that would then merge back on to the road at a single point.

This work would happen along with a proposal to move I-75 traffic above I-69, instead of below like it is now.

"We are hoping we can take care of a lot problems that occur out there," Block said.


Limiting the amount of crashes that happen in the area is another reason for this alternative.

"Safety is definitely a big problem. It's part of what we are looking at," Block said. "A lot of the crashes that do occur through that area are a result of those short taper lanes, ability to get on or off the expressway."

Limiting crashes would allow officials to keep the lanes open near the interchange.

"We have a crash and then it's a safety concern and additionally it compounds to an operation problem where that causes a two lane closure to handle the crash," Block said. "And now we are left with one lane open and we get backups that are quite significant as well."

Any changes to the interchange will not take place for several more years. Block said that it would 2026 at the earliest before any construction begins.

abc12.com/content/news/Public-shares-feedback-on-states-proposed-change-to-I-69I-75-interchange-566105591.html

[Flint1979]

I saw this on the news about a week ago. It would be nice to see that done then I-75 can go over the railroad overpass instead of under it like it does now too.

I-75 should be eight lanes in this area as well.

[froggie]

I've never heard of a proposal like this before. Has this ever been tried anywhere else in the country that anyone knows about?

I-189/US 7 South Burlington, VT
I-394/MN 100 Golden Valley, MN

[wanderer2575]

I've never heard of a proposal like this before. Has this ever been tried anywhere else in the country that anyone knows about?

It's only a partial interchange, but Michigan just did it this year at I-96/I-196 in Grand Rapids while also adding a braided exit ramp to M-44/M-37.  The ramp from westbound I-96 to westbound I-196 used to go over eastbound I-96, and it now goes under.

[Revive 755]

I've never heard of a proposal like this before. Has this ever been tried anywhere else in the country that anyone knows about?

US 40/US 61 at I-270 in the St. Louis area.  US 40 used to go under I-270, but became the top level when the previous cloverleaf was rebuilt into a turbine-semi direct hybrid.

[sprjus4]

I've never heard of a proposal like this before. Has this ever been tried anywhere else in the country that anyone knows about?

I-95 / VA-630 Courthouse Rd in Stafford, VA.

[andy3175]

It looks like the effort to modify the I-69/75 interchange is still being discussed and planned. It will be very costly. The interchange study webpage is at https://www.michigan.gov/mdot/0,4616,7-151-11058-498332--F,00.html

Here is an article from January on the current effort:

https://www.mlive.com/news/flint/2021/01/genesee-county-could-add-700-million-i-75-i-69-interchange-mega-project-to-long-range-plan.html%3foutputType=amp

The county is preparing to add a whopper of a transportation project to its long-range plans -- a $700-million reconstruction of parts of Interstate 75 and I-69 and a modernization of the area where the highways connect. ...

The project area carries a high traffic load and has a collection of problems including difficult merges, a high crash rate, flooding and prime-time congestion.

The plan for fixing those problems and improving safety includes building I-75 into an elevated span over the top of I-69 and CN Railroad property, the addition of collector and distributor roads on I-75 to separate thru traffic from vehicles trying to take ramps on or off the highway, and improved lighting.

Elevating I-75 over the railroad property would also remove the potential for flooding of the expressway, MDOT officials said in a 2019 presentation of the plan at open houses in the area.

SM-G975U

[The Ghostbuster]

When I clicked on the Michigan Live webpage, it said "Page Not Found", meaning it is a dead link. The DOT webpage worked fine, on the other hand.

[JREwing78]

When I clicked on the Michigan Live webpage, it said "Page Not Found", meaning it is a dead link. The DOT webpage worked fine, on the other hand.

https://www.mlive.com/news/flint/2021/01/genesee-county-could-add-700-million-i-75-i-69-interchange-mega-project-to-long-range-plan.html

[thspfc]

I’m always skeptical of spending on large road projects in heavily declining areas such as Flint. If the road is completely falling apart, then sure, but I don’t see a reason to spend money on roads that won’t see increased traffic volumes anytime soon.

[GaryV]

I'm guessing that by far most of the traffic on I-75 and I-69 in Flint is not from Flint.

[Flint1979]

This stretch of I-75 should be eight lanes anyway. It carries between 90,000-100,000 VPD while the stretch between Flint and Saginaw that is eight lanes doesn't carry as high of a volume. The highest on that stretch is between MM 125 and 126 at about 87,000 VPD.

I don't get why they didn't go south of the northern terminus of I-475 with the eight lanes as the traffic volumes stay steady in that area dropping down to 76,000 between 122 and 125 and then picking back up to around 90,000 south of there until the US-23 split which would include the area being discussed here. US-23 is actually busier than I-75 south of the split btw.

This would ease a lot of problems though. The on ramp going to SB I-75 from EB I-69 the ramp has to cut over to miss a train bridge that is in the way causing merging problems there. The ramp going from EB I-69 to NB I-75 isn't the worst but it's a 25 mph ramp that is a circle. I-69 has been worked on in the area the last few years and is in need of more repairs itself.

This is a very congested area. You have I-69 traffic coming onto I-75, you have US-23 traffic coming onto I-75, you have Bishop Airport traffic coming onto all three highways and vice versa. Plus you have a GM plant right there at the Bristol Road exit.

[Ryctor2018]

Furthermore, (hopefully) one day US-23 will be widened to six lanes from Flint to Toledo. This I-69/I-75 project could help with that expansion.

[wanderer2575]

I don't get why they didn't go south of the northern terminus of I-475 with the eight lanes as the traffic volumes stay steady in that area dropping down to 76,000 between 122 and 125 and then picking back up to around 90,000 south of there until the US-23 split which would include the area being discussed here. US-23 is actually busier than I-75 south of the split btw.

Until they are able to widen all of I-75 between the northern I-475 terminus and the I-75/US-23 split, it's pointless to widen any part of it, at least southbound.  I don't expect it will all be done at once, but there isn't anything lined up right now for even the possibility of getting funding and ROW for all of it.  There is more of a case for having widened north of the northern I-475 terminus because the 3di can be used as an alternate for I-75 (not US-23) traffic.

[sprjus4]

I don't get why they didn't go south of the northern terminus of I-475 with the eight lanes as the traffic volumes stay steady in that area dropping down to 76,000 between 122 and 125 and then picking back up to around 90,000 south of there until the US-23 split which would include the area being discussed here. US-23 is actually busier than I-75 south of the split btw.

Until they are able to widen all of I-75 between the northern I-475 terminus and the I-75/US-23 split, it's pointless to widen any part of it, at least southbound.  I don't expect it will all be done at once, but there isn't anything lined up right now for even the possibility of getting funding and ROW for all of it.  There is more of a case for having widened north of the northern I-475 terminus because the 3di can be used as an alternate for I-75 (not US-23) traffic.

But the segment north of I-475 is already 8 lanes and sufficiently carries its volumes. There’s no need for any further expansion.

[Flint1979]

The part I'm talking about is between the north end of I-475 at MM 125 and the US-23 split at MM 115. I use this highway a lot so I'm familiar with it. Where it drops from four lanes to three lanes going southbound it clusters traffic up, some traffic gets off at I-475 but most traffic stays on I-75 and the traffic volumes pick up again after Pierson Road at MM 122. Then it gets clustered up from about MM 118 at the Corunna Road exit all the way until the US-23 split at MM 115. You have I-69 and I-75 intersecting, you have US-23 coming in with a ton of traffic, you have Bishop Airport traffic, you have a big GM plant right next to the I-75 and I-69 interchange.

I think I-75 should be eight lanes from Bay City to the US-23 split in Flint and then six lanes from there until Auburn Hills where it picks up another lane again by the curve where the Palace use to be.

[JREwing78]

This is a view of I-75 facing south from I-69. Note the arrangement of I-75 at the bottom, under the rail road tracks, and then the NBD I-75 to WBD I-69 ramp and SBD I-75 to EBD I-69 snaking above it:
https://goo.gl/maps/7qExscNzp6KR6MtF7

There's a lot going on, with interchanges at Miller Rd to the north and Bristol Rd to the south that needs to be accommodated. And, this railroad overpass:
https://goo.gl/maps/BWz5MRWzdUHL1Cfh7

[DJStephens]

The I-75 mainlines have inadequate shoulders, both inside and outside.  Appears that it has always been six lanes, three in each direction, going by the crack seal, on the asphalt, over the joints of the underlying concrete pavements.   So that is the area that is prone to flooding.   

[Terry Shea]

So what's the status on this project?  I went to the MDOT site and it was absolutely no help at all...but it rarely is so that's no big surprise.  Has this been finalized and is there any timetable?

[Flint1979]

So what's the status on this project?  I went to the MDOT site and it was absolutely no help at all...but it rarely is so that's no big surprise.  Has this been finalized and is there any timetable?

I haven't heard much else about it lately. It's still something that needs to be done IMO. MDOT has been working on I-69 and I-475 but not doing much on I-75 the last few years.