A new bridge connecting Portsmouth, N.H., and Kittery, Maine, features what engineers believe is the first-ever use of precast-concrete segmental towers on a vertical-lift bridge.
A mechanical failure of a sheave in the south tower of the 76-year-old, 2,804-ft-long Sarah Mildred Long Bridge on Aug. 21 has led to a permanent closure—10 weeks before construction of its replacement would have closed it anyway.
