Gephyrophobia: An abnormal and persistent fear of crossing bridges. Sufferers of this phobia experience undue anxiety even though they realize their fear is irrational. Their fear may result partly from the fear of enclosure (claustrophobia) or the fear of heights (acrophobia). Phobic drivers may worry about being in an accident in busy traffic or losing control of their vehicles. High bridges over waterways and gorges can be especially intimidating, as can be very long or very narrow bridges.
Fear of bridges is a relatively common phobia although most people with it do not know they have something called "gephyrophobia." However, the derivation of the word "gephyrophobia" is perfectly straightforward (if you know Greek); it is derived from the Greek words "gephyra" (bridge) and "phobos" (fear).