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Interchange Index
Overview: This interchange is located about 2 miles northwest of downtown Knoxville. I-640, which serves the purpose of a northern bypass through Knoxville's northern suburbs, runs from southwest to northeast. I-75, on its way around central Knoxville, multiplexes with I-640 west of this interchange, and leaves in a northwesterly direction. The expressway leaving the southeast end of the interchange is I-275, which leads into downtown Knoxville. (This may have been I-75 at one time...?) The last highway involved is US 25W, which enters from the west side of the interchange. It leaves on the same freeway as I-640, in a northeasterly direction.
Interchange Description: Excluding any ramps to or from US 25W, this interchange is remarkably similar to the WhereRoadsMeet logo; it is a "cloverstack", with two cloverleaf ramps on opposite corners and two semi-directional flyovers to replace the two missing cloverleafs. (In other words, it's a four-level stack with one level replaced by a pair of cloverleaf loops.) The cloverleafs here would be in the southern and northern quadrants, if it were not for US 25W. Instead, the loop ramp from I-275 NB to I-640 WB actually branches off from the US 25W ramp rather than I-275 itself. The other ramps serve traffic to and from US 25W; there are two ramps feeding US 25W from I-640 WB and from I-275 NB, and ramps from US 25W EB to I-640 WB, I-640 EB, and I-275 SB.
History: The portion of I-640 west of here is newer than the rest of the highways, and was not completed until the early 1980's. At that time, I-640's western terminus was here, and I-75 continued southward along the current I-275 to "Malfunction Junction" downtown (soon to be featured on WhereRoadsMeet), where it joined I-40 and traveled westward. I-275 didn't exist until I-75 was rerouted onto the new I-640.
Advantages: This interchange is a good way to quickly move traffic through a pretty important junction of four major highways. There is no weaving, which is always good; also, the flyovers provide a quick way to switch highways, especially for northbound I-75 traffic.
Disadvantages: Other than cost of the excessively long flyovers, there are not too many problems here. The long, curving bridges must have been fun to engineer and build...
Thanks to an m.t.r post by Patrick Humphrey for some information on the history of the interchange.