Word to describe someone who is a lover of bridges

The word is pontist.

1. A historic bridge enthusiast who enjoys either lobbying for preservation and/or who enjoys visiting and photographing historic bridges.
2. Anyone who enjoys working with or visiting/photographing bridges of any kind.

[Urbandictionary]

It also appears in one of the reviews of the book "Bridges of the World: Their Design and Construction" (By Charles S. Whitney):

A book to delight the heart and eye of a pontist whether he be an admirer and lover of bridges or a designed or builder..." -Saturday Review of Literature

It is coined from Latin pont-, stem of pons "bridge". (See: similar words)

Another example from the book "Historic Iron and Steel Bridges in Maine, New Hampshire and Vermont" (By Glenn A. Knoblock):

This is a book intended for anyone who has an interest in bridges, whether they are a bridge enthusiast ( a "pontist"), civil engineer, native New Englander or someone from outside the region.

The Greek word for bridge is γέφυρα, so a lover of bridges would be a gephyrophile (or maybe gefurophile, depending on how the Greek is to be transliterated).