Northside Strangler Interchange
The US-31 Freeway project was largely complete within the metro a few years ago but since you may have noticed there has been some major growing pains. The "Northside Strangler" interchange as we are calling it is showing evidence of some poor design decisions made by engineers that designed the interchange.
INDOT Cost Cutting
3 Lane Weave
Looking at the southbound ramps to I-465 there are several factors as to why this design is so bad. First US-31 traffic (mainline traffic) has to EXIT from the freeway. Mainline traffic should never have to exit from the freeway. A freeway should not exit from itself that just doesn't make sense. Secondly Too much traffic has to cross over other traffic. There is a large amount of traffic entering from the onramp coming from 103rd street. This traffic is trying to merge across 3 lanes to the right while other traffic is trying to merge to the left. Gore Areas are too large. This encourages people to cross over the gore areas to get to where they want to go rather than waiting until the line is broken where they should ACTUALLY attempt to make their lane changes. These gore crossings only exacerbate the problem further adding to the gridlock. Driver behavior is also a factor. At a proper merge etiquette should dictate that you take turns and merge, one left..., one right..., and so on..., so that everyone gets to go and the vehicles behind don't suffer from gridlock. Unfortunately due to poor road design and selfish drivers there is gridlock at times here. The key is that better road design can alleviate what human behavior experts and attempts at social engineering cannot.
This leads to a couple of conclusions. A retrofit of I-465 to the west of US-31 to I-865 is long overdue. The road is substandard and deteriorating. Has a dangerous left exit, and not enough through lanes to handle the traffic volume that it is currently expected to carry. Before that can be done however, something needs to be done to address the design shortfalls of the Northside 31 Spaghetti Junction. The easiest fix is to extend the second lane down to I-465 and look at employing ramp meters to mitigate merging at this point. This is not a perfect solution but at least it will get traffic moving.