Great article! I'm very happy to see a spotlight focused on this topic. I've been a resident of Springfield for years. I work downtown. I run from my front doorstep over the bridges 4-5 times a week. I encounter State and Union on a constant basis. From an urban planning perspective I believe this is the most contentious issue facing future development of Springfield and Downtown. I also believe it is one of the lowest hanging fruits we could hope for. The problems I see are in general upkeep, missing sidewalk section, overgrown vegetation, flooding, lighting, trash. On a short-term basis fixing those problem would bring a sense of cohesiveness between the two neighborhoods.
In general, it makes more sense to think of State and Union as if the two roads were a freeway. Their purpose is to move far-flung residents across town. As a local I tend to avoid the chaos that can ensue. Multiple grid disruptions make intra-neighborhood travel a sport only local know how to traverse. There is also a vacuum effect created by what is best described as a borderland, void of community and a sense of place. It's a place most Jacksonvillian what to get the hell through as quick as possible. The sad part is that some of the cities most exploitable properties sit and root for lack of interest.
The city or JTA should create a task for to deal with some of the issues created in such a vital area. The pay off could have major implications citywide.