Complex sentence: In 1994 the bridge had extensive work done by Jan Lewandoski, in which the bridge was completely removed from its crumbling marble abutments, and new concrete abutments were created for it.
Split into simpler sentences: In 1994 the bridge had extensive work done by Jan Lewandoski. The bridge was completely removed from its crumbling marble abutments, and new concrete abutments were created for it.