At the Delaware Memorial Bridge, the phobic are not as rare as one might expect, with 323 transports in 2017 and 468 the year before. About 60 percent are repeat customers, according to Col. Richard Arroyo of the Delaware River and Bay Authority, which operates the twin suspension bridges; some regulars call ahead to schedule appointments when they know they will be traveling to the area. Men are just as scared as women, millennials as bridge-shy as boomers.