No, the bridge is not needed strategically. It would be a centerpiece of the trail system. The bridge was necessary for a train route, beginning perhaps a century or more ago. Maybe locals would know where those tracks extended. I assume it curled the mile west through Delphi proper. Toward the south I have no idea.
The routing must have dictated crossing the ravine in that area. It was strictly a locomotive bridge so no use for pedestrians or to connect sections of the city, per your example of Europe. The first time I visited Europe decades ago I was amazed at how vital and interesting the bridges were. The shopping bridge in Florence comes to mind first. Also the great variance of bridges in Copenhagen. I could keep going...
I'm not even sure if that small enclave of Delphi behind the bridge even existed when the train tracks were built. Those homes are more widely spaced than Delphi proper. Freedom Bridge over State Road 25 now serves to connect one side of Delphi to the other side. Delphi proper is on the northwest of 25 while the bridge is on the southeast side. From what I've read the bridge trail renovation plans include an extension of the trail all the way to center Delphi itself. Right now it is possible to walk that route but it would be clumsy along the east/west main road through town. I doubt many people do it.
There are other functional bridges in Delphi. I saw one at Canal Park that did serve to unite small communities on two different sides. I believe that was called Wabash canal. But at Monon High the creek does sort of an S pattern underneath the bridge, if you can envision that. The girls were killed near the top left swirl of the S. Then the middle of the S would be directly underneath the bridge. Then the creek loops around to the right (north) once beyond the bridge.
Crossing the creek in that area is hardly a daily concern. That is a very low populated section of a very low populated town. State Road 25 crosses the creek not far from Freedom Bridge. That road would account for virtually every crossing.
Scroll lower at this link and the layout of the city is visible. Monon High Bridge Trail would be far right center of the map. You can see how isolated it is from the remainder of the town. I like that map because it shows the layout of the old railroad lines. As I suspected, it looks like the railway route through Monon High looped west to connect to other main lines in Delphi proper, and then exited with one track northwest near Canal Park and toward Pittsburg while another track curled southward near the current site of Trailhead Park. BTW, that's Pittsburg the Indiana version and not Pittsburgh, PA roughly 400 miles east:
Delphi Canal Center
