How do we decide when and where a pedestrian bridge is necessary?

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fywydujyl
How do we decide when and where a pedestrian bridge is necessary?

Dear all, I am sure that we have all heard about the tragic collapse of the pedestrian bridge during construction in Florida. I have been thinking about this project a bit and the 'needs' that it was intended to address. Clearly there was a well established need for an improved pedestrian crossing at this location (growing demands on both sides of the road), but why the choice of a bridge instead of changing the road environment and the intersections? Obviously we know how to calculate the 'benefits' accruing to improved vehicle circulation at an intersection due to pedestrians no longer crossing there, but what about the pedestrian perspective? Is crossing a bridge 'obviously' better than crossing a well designed intersection? Why or why not? How would we even begin to model and quantify this 'pedestrian' perspective? *How do we decide when and where a pedestrian bridge is necessary, and whose perspective is considered in that decision?* Here is some background info about the project and its funding - TIGER Grant: bringing the University and City together <http://panthernow.com/2013/09/29/university-only-one-of-its-kind-to-rece.... From the project proposal we see that “These infrastructure improvements will support the economic growth of a major public research university and an adjacent small city [Sweetwater].” Given that the "overall purpose of UniversityCity would be to increase the number of the transit riders in the area, improve modes of public transportation, foment pedestrian-oriented commuting within the University-Sweetwater region and provide initiatives for local businesses," why was a pedestrian bridge chosen instead of some other modification to the street environment? “There used to be a concept that the University should be a suburban development with controlled access.... The new thinking is that we are part of the community, we are opening our doors to them.” “We, through UniversityCity, are trying to be a catalyst for an urban place.... We are trying to leverage good academic thinking, transportation and urban design. It will be a work in progress for many years.” Clearly this project was developed with nothing but good intentions <https://www.chronicle.com/article/Engineer-Connects-His-Research/142787>, and I am not really interested in the technical details <https://www.engineering.com/BIM/ArticleID/16670/A-Bridge-Too-Faux-Florid....... I have been able to find one analysis of different technical specifications for a pedestrian bridge <https://web.wpi.edu/Pubs/E-project/Available/E-project-031013-103455/unr..., but there was no discussion of other potential design solutions. So how do we balance traffic flow with the needs of other people who use the road network in our models? What types of 'performance measures' might be relevant? Looking forward to hearing your thoughts and ideas! Best regards, Zvi