Bad interchanges

[TheCatalyst31]

The US 65/US 69/IA 5 interchange south of Des Moines has both this tiny merge area and a hard right turn on an outer cloverleaf ramp, both of which look like they could be easily fixed but weren't.

[Henry]

* Any interchange where a mainline interstate uses a loop ramp.

How about two.  The Big X near Moline, Illinois has both I-80 and I-74 go through loops. 

And that's the thing I hate most about IL, a state that builds cloverleafs where others would've built some sort of directional interchange at least (if not a stack).

I still dread the Rapid-Fire ramps in Chicago; in fact, entrances onto and exits off of the left lane scare the fuck out of me.

[CapeCodder]

Before they were rebuilt, I'd have nominated both the 170 and 270 interchange as well as the 64/40 and 170 interchange in the St. Louis area. Even in North County along 270 was bad, particularly on the wb lanes as those ramps shot you past oncoming traffic along Dunn Road. Good to see that that area has been improved.

[Bickendan]

I-405 from SW 6th Ave to 12th Ave, northbound. US 26 merges then immediately splits away from I-405. Traffic trying to get onto I-405 north has to weave through traffic getting exit US 26 west, which can back up onto the bottom deck of the Marquam Bridge, I-5.

[WillWeaverRVA]

The US 60/VA 150 interchange is a very compact cloverleaf that is extremely inadequate given traffic volumes on both routes. The merge area between the loop ramps is extremely short (about 400 feet) and traffic routinely backs up onto VA 150 during rush hour.

It's about to get a whole lot worse because of massive redevelopment of the former Spring Rock Green shopping center in the northwestern corner of this interchange - Springline at District 60 will feature high-density housing, shopping, a business center (including some relocated Chesterfield County offices), and a multipurpose sports and concert arena. Reconfiguration of the interchange or even adding pedestrian accommodations was never considered as part of this project, it still isn't, and this area will probably become a traffic nightmare once everything is finished.

[MATraveler128]

I-290/395 where it meets I-90. Absolutely confusing for anyone not familiar with the area. It backs up 290 for miles and people jumping in and out last second. On summer weekends and holidays forget it. Not to mention it's under construction.

I'll also mention I-84 where it meets I-90 in Sturbridge mainly heading eastbound. That eastbound transition onto I-90 should be at least 2 lanes as I once got backed up all the way back to Exit 5.

[ilpt4u]

The I-88/290/294 interchange mentioned before is completely being rebuilt as part of ISTHA's Central Tri-State project, and most of the mentioned issues here are being addressed

[lepidopteran]

I nominate the I-95/MD-32 interchange.  Specifically because two of the movements are left-entrances onto busy I-95.  Not only is 95 4 lanes in each direction at that point, but the curve geometry of the ramps is tight enough that you really do not have a lot of time to accelerate to fast-lane speed.  (While the corresponding off-ramps are left exits, Route 32 is narrower and has a lower speed limit, so that's not really as problematic. Plus, they are exit-only lanes in both directions.)

[LilianaUwU]

I nominate the A-73/A-540/QC 175 interchange in Québec City. Hopefully the current reconstruction fixes it, but it's very substandard, a problem that's made worse by the incredibly high traffic volume, as there is no other way by road between Québec and Lévis.

[PColumbus73]

In Myrtle Beach, the interchange with US 501 and SC 31 needs some improvements

https://www.google.com/maps/@33.7402375,-78.9523951,956m/data=!3m1!1e3?entry=ttu&g_ep=EgoyMDI0MDgyMC4xIKXMDSoASAFQAw%3D%3D

This interchange is a unique double-trumpet interchange with left exits off of SC 31, a limited-access freeway. From both directions of SC 31, the left lane becomes an exit to US 501. (SC 31 South to US 501 South, and SC 31 North to US 501 North), the interchange also has left lane entrances onto SC 31. It's also a fairly compact interchange, likely due to the wetlands.

The areas of concern I see are:

On SC 31, thru traffic has to be aware of traffic merging in from both the left and right, more so for US 501 traffic (both directions) to SC 31 North. You'd see it better on Streetview, but the sightlines aren't great for traffic merging from/exiting and feel like blind merges/exits.

You can see from Streetview, the guardrail on the ramp from SC 31 South to US 501 South indicates drivers don't anticipate the curve, maybe due to the long ramp leading to it?

On SC 31, the speed limit drops to 50 MPH through the interchange.

How I would fix it:

I would extend the right lane accel/decel lanes at least 1/4 mile beyond the start of the left lane drop & end of the left lane add. Due to the curves through the interchange, I would extend the accel/decel lanes to either (a) a straight section of roadway for better visibility or (b) to stagger the merging / lane changes due to a dual left-right exit at all points of SC 31.

I would add rumble strips in the lane for the left exits from SC 31 to US 501.

Assuming SC 31 is going to be a part of a future I-73, this interchange might need to be reconstructed to remove the left movements. That would be something for the 'redesigning interchanges' thread. In the short-term increasing the visibility and merge area on SC 31 should be a priority.