I-75 in downtown Dayton

[Tom958]

Crazy early sixties design with too many onramps and offramps on both sides of the road replaced by a drastically simplified layout. Is it regarded as successful? What do you think about it?

The actual layout, because I feel like writing:

I-75 is a consistent six lanes through metro Dayton, from I-675 (it's eight lanes all the way south from there to I-275) to well north of I-70. Downtown, the new scheme consists of what I think of as two pairings: one of the US 35 stack interchange and a half diamond for First and Second Streets, and another for Third Street and the OH 4 freeway. Within these two pairings, the onramps and offramps are all two lanes and both lanes of each onramp extend all the way to the next exit a distance of half a mile. The I-75 roadways have either three lanes or five, period. There are no terminated lanes at the entrances, no option lanes at the exits, and no need for those newfangled APL signs. The signage southbound is almost insultingly simple, with down arrows on both the pullthroughs and the exits, which, IIRC, is noncompliant with the MUTCD.

Northbound isn't quite so straightforward, because... within the northern pairing, a diamond interchange for Main Street is grafted onto the ten-lane section. Doing this has no impact on the driving experience to/from the north because the ramps to and from Main Street are braided with those for OH 4, with no weaving or decision-making required. However, there's no good way to sign a single lane exit followed closely by a dual lane drop exit, which has lead to the use of nonstandard and possibly confusing signage for the Main Street and OH 4 exits. And, getting on I-75 southbound from Main Street requires merging into lane five, then changing lanes twice to get to lane three, all in less than half a mile. Hopefully, if traffic's too heavy to make that merge, drivers will calmly take the exit instead of veering crazily toward lane three, but any who do will have to have to double back to get on at First Street, because the half diamonds are staggered rather than in a split diamond, presumably to increase the weaving distance on I-75.

So... 

[GreenLanternCorps]

I used to drive I-75 on a regular basis and drove it daily from 2002-2005.

The road is a MUCH better drive after the re-build.