Well, maybe, unless providing this new alternate method of transit decreases congestion and pollution, improves mental and physical health of its citizens, and by extension their productive capacity and the amount of income or other taxes that they might pay.

While it's laudable that the City considers funding sources for various projects, particularly so given its many budgetary issues, it is flawed to think that the cost benefit analysis in considering whether to invest in a given project is as simple as "will this project pay for itself directly through fees that it generates".

Money is fungible and the City has the ability to issue bonds. It should consider the effects of what it invests in on the overall health of the urban system at large.

We do this for things that are considered "social projects", but not for infrastructure, but this is an arbitrary distinction, and as always, it's all connected!

Note: I don't intend here to argue that any of the what are called "social projects" are worth or not worth their expense , just calling attention to what I see as an odd disconnect in how we determine what is worth funding.

...as a sidenote, your point also only holds if all of these trips are replacing previously vehicular traffic going over the bridge. Also note that you could have alternatively chosen to focus on the decrease in wear and tear on the bridge!