The source from Google comes from Wikipedia, which in turn comes from a book by Larry Millett, where he uses the phrase “This is believed to be the busiest intersection” with no indication of the ultimate source. Although it’s possible he’s trying to count pedestrians or light rail traffic in the totals, there’s no indication of such. Another writer emailed Mn/DOT asking if they knew, and the reply was they don’t officially know.
There are other factors besides overall volume, both political and engineering related, driving the location of potential projects, so keeping such trivia apparently isn’t a priority. They explained that when they do, their methology is to add up all the legs of an approach and divide by two while cautioning that some data, especially for minor side streets, might be way off due to extrapolation from years ago rather than fresh actual data. But since it’s the best we have I thought I’d see what the busiest intersections are using it.
As it turns out, Snelling and University, at traffic volume 48,550, isn’t currently even in the top 25. Another writer suggested I could present it as a story, so here is the top 10. (This list specifically excludes any that might involve freeway ramps).
#1 is MN 252, at 66th Ave N, Brooklyn Center (Traffic Volume = 68,850). This is also in the top 10 most dangerous as far as crash statistics. Just down the road, #2 is MN 252 at 85th Ave N (66,950); #6 is MN 252 at Brookdale Dr. (61,975); #9 is MN 252 at 73rd Ave N (61,515). Also of note, MN 252 at 70th is in the top 25. The original 1970s era plan was to build MN 252 as a freeway, but there was local opposition from the city, that wanted opportunity for economic development. So it was built as a wide suburban style road in the 1980s, and things have gone downhill rapidly from there. Studies have shown that with 2035 traffic a freeway facility is necessary, but unfortunately the corridor was removed from the long range freeway plans due to lack of funding. Brooklyn Center is pursuing a single interchange at 66th in the interim, while not letting go of the long term goal of a freeway facility. A pedestrian fatality prompted building a pedestrian overpass at 85th, but not much else has been done.
#3 is MN 65 at 109th Ave NE, Blaine (64,650) and #4 is MN 65 at 92rd Lane NE (62,500). The intersection on MN 65 at County 14 (55,550), was replaced with an interchange, but momentum and funding has stalled after that. The long term goal is still a freeway northwards of US 10, but as of now unless the local agencies get some special funding nothing further seems likely.
#5 is US 10 at Fair Oak Ave, Anoka (62,325). Just down the road US 10 at Thurston is also in the top 25. US 10 was the subject of a very grandiose $300 million plan to relocate the mainline next to the very heavily used railroad tracks, and bridge the cross streets over both. Significant right-of-way has been acquired, but like MN 252 this got yanked from the long term plans, but replaced by more modest spot improvements at the traffic signals, either with full interchanges or removing some movements. I don’t know if the relocation plan is officially dead, or in deep, deep ice. There’s an intersection being built and Armstrong, and Elk River wants one built at Twin Lakes Road, but afterwords focus may shift to more modest improvements at Fair Oak and/or Thurston. There is a jaywalking problem between Thurston and Fair Oak which included a pedestrian fatality, so discussions are underway about building a fence. Building a third lane while keeping the traffic signals for the time being has also been discussed.
#7 is MN 15 at W Division St, St Cloud (61,750). MN 15 was planned, and ROW acquired for a freeway facility, but was built as a wide suburban style road instead. Exactly why is unclear, a Mn/DOT employee claimed that St Cloud fought them tooth and nail against a freeway so they could sell the excess land for commercial development; others have said that with the project languishing for decades because of funding the point was to sell the land to pay for building something as opposed to having nothing. At any rate, all parties now want a freeway, and it will be substantially more expensive due to extensive retaining walls now needed, but as usual there’s no money to pay for it. As a popup project one of the other intersections was replaced with Minnesota’s first diverging diamond, and the city avoided compounding the problem by building another interchange south of town, rather than adding yet another signal.
#8 is Cedar Ave S at 140th St W, Apple Valley (Traffic Volume = 61,700). Nearby, Cedar at County 42 is in the top 25. There were various plans, including depressing the through lanes through Apple Valley (which the city took a dim view due to lack of access and how congested the frontage roads would be, essentially favoring the people bypassing Apple Valley), or just building interchanges at some of the higher volume intersections. One innovative proposal was to bridge the northbound and westbound lanes over the southbound and eastbound lanes, thus removing the left turn phases from the signals. Although a 2009 Dakota county study suggested an interchange at 42, unfortunately with the more modest improvements for the Red Line I doubt any further improvements will be done anytime soon.
Rounding out the list at #10 is County 42 and Nicollet Ave S, Burnsville (61,350). This one seems unlikely to ever be fixed. A plan to build a loop from southbound I-35E to northbound I-35W in order to eliminate the signal at the ramp to north I-35W was dropped when it was revealed it would make traffic worse due to more traffic being sent through the Nicollet intersection. Although I’ve seen the suggestion of a single point interchange at I-35E, studies seem to suggest giving up on moving traffic effectively through this stretch, instead compensating by moving traffic faster east and west of here. Ultimately I think the answer here is to build ramps of County 38 to provide an alternate route to get to I-35W.
So if University isn’t even close now, was it once? The book and Wikipedia state “around 64,000”. Going back 10 years I find 61200. But even using the more generous figure, even without looking much there were several high volume suburban intersections at the time, for example US 169 at County 81 = 79400, and US 169 and Anderson Lakes Parkway, 67550. Also interesting, is traffic volumes on the intersections that have been replaced by interchanges in recent years, some of these are local “popup” projects and some were driven by Mn/DOT.
US 10 / Armstrong Blvd = 39,680
MN 7 / Woodale Ave = 42,600
MN 7 / Louisiana Ave = 49,300
US 10 / County 96 = 59,100
MN 13 / County 5 = 66,000
MN 13 / County 101 = 60,100
County 42 / County 17 = 11,450
US 169 / County 69 = 36,430
MN 36 / English St = 76,400
MN 101 / 141st Ave = 53,700
MN 36 / Hilton Tr = 45,700
So what factors do go into building interchanges? First is benefit/cost analysis. Basically you add up all the benefits and divide by costs. Not just physical construction costs, but future maintenance, drivers time ($16.00 per person-hour), costs of crashes (your life is worth $10,300,000, so you can see why only one of two fatalities can easily justify substantial improvements. This can throw things so out of whack the instructions are to make absolutely sure it’s correctable by proposed improvements, not say a random drunk driving into a tree), etc. And obviously the heaviest used intersections may not be the most congested, there’s other a lot of other factors.
Second, sometimes there’s a desire for continuity. We’ve decided we don’t want traffic signals on rural expressways, at least the more heavily traveled ones, so at only 21,850 for the higher one, the signals on US 52 at Cannon Falls are gone (although these are quite often also serious safety issues).
Third, sometimes local desires can short-circuit the overall planning process and get things bumped up, my own phrase is pop up projects because they sometimes pop up out of nowhere. Mn/DOT will usually humor these, provided someone else pays for a lot or most of them.
My own feeling is somewhat ambivalent. I never object to spending money expanding highways, and if Ramsey wants to play “Sim City” and get funding for an interchange at Armstrong ahead of the much busier ones on the corridor, so be it; a lot of times it’s this project or nothing. There’s no one championing and finding funding for a pop up project at Fair Oak at the moment, even if the Armstrong project didn’t happen. However this can sometimes lead to sub-par results, that we’re then stuck with for a long time. For example a single lane flyover was built from I-94 for northbound MN 101, rather than waiting for a much more comprehensive system interchange, and the new “interchange” at US 52 and Goodhue County 9 even had to have substandard ramps in order to qualify for funding!
(And although I’m no longer really active on Wikipedia, I did go in to correct it.)