Last week's answer

Question: When Caltrans opened the new $6.4 billionA single continuous main cable loops around the western end of the bridge deck itself, transferring compression directly into the heavy steel-and-concrete roadway box girders. East Span of the San Francisco–Oakland Bay Bridge over Labor Day weekend in 2013, engineers unveiled a single-tower Self-Anchored Suspension (SAS) design. Unlike traditional suspension bridges (like the Golden Gate or Brooklyn Bridge) that anchor their main cables into massive concrete gravity blocks buried deep in the earth, how does a self-anchored suspension bridge resist the immense tension of its main cable?

Answer: A single continuous main cable loops around the western end of the bridge deck itself, transferring compression directly into the heavy steel-and-concrete roadway box girders.

A self-anchored suspension bridge differes from the more traditional suspension bridge in that it utilizes one cable, as opposed to two, that continuously loops around the decks of the bridge. Engineers of the San Francisco-Oakland Bay Bridge used this design as it has the ability to handle higher traffic volumes and potential earthquake damage. 

Sources: American Bridge