Overview: The river at the north edge of the photo is the Ohio river, forming th border between Kentucky and Indiana. The north-south expressway towards the western edge of the picture is I-65. From here, it runs southward into downtown Louisville and northward into Indiana. The main east-west expressway is I-64. This expressway splits at the eastern end of the overhead view, where I-64 takes the southern fork. I-71 begins at this split, running northeast from this point towards Cincinnati.
From I-65, the exit to I-64 and I-71 (which is one ramp) is Exit 137. The exit from I-64 to I-65 is exit 5, and the eastbound exit to I-71 north is Exit 6. The split of I-71 between I-65 and I-64 westbound is Exit 1.
Interchange Description: The western half of the interchange, where I-64 meets I-65, is a fairly simple variation on a 4-level stack. First of all, notice the ramp from I-64 westbound to I-65 southbound, and I-64 eastbound to I-65 northbound. These two ramps, instead of running next to each other as the other two left-turn movement ramps do, cross each other twice in the interchange. This was probably done because I-65 is not elevated highly enough to allow for two sets of ramps to cross under it at the same point, which would have been necessary in a standard 4-level stack setup. The second, and more major, modification is the fact that, instead of passing through the middle of the interchange, the through lanes of I-64 pass around the outside of the interchange. Again, this was probably done to avoid elevating I-65 any higher than absolutely necessary. Also, had the northernmost ramps been moved much further north, they would have intersected the I-65 mainline over the Ohio River instead of over land. This would have made the engineering and construction of the bridge much more difficult.
The eastern half of the interchange is the intersection of I-64 and I-71. This portion is a little more conventionally designed. First of all, there are no ramps from I-71 southbound to I-64 eastbound, or I-64 westbound to I-71 northbound. These "U-turn" connections are provided by local streets or by I-264, a short distance to the east. The ramps from I-65, after merging together, feed the mainline along with a ramp from I-64. A slip ramp leads from this ramp to I-64 eastbound. The westbound half of the interchange is built in much the same fashion, with I-71 splitting around I-64's westbound half, which then splits between I-64 westbound and I-65.
Advantages: This is actually a great design for the circumstances encountered. On this small strip of land, an interchange was built that has little weaving, no excessively tight turns, and direct connections between all of the freeways involved. In addition, the problem of having ramps intersect I-65 over the Ohio River was avoided by relocating the entire interchange inside the median of I-64. It is a very unorthodox approach to interchange design, but in this scenario, it seems to have worked.
Disadvantages: One major disadvantage here is the frequency of left exits and entrances on I-64; in fact, all four ramps between I-64 and I-65 are left exits or entrances where they join I-64. Only the ramps to and from I-71 enter and leave from the right side. In addition, there is a small amount of weaving on the ramps between I-65 and I-71, but this is over a long distance and probably not much of a problem.