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Elevated highways, despite their mass and size, are like a house of cards. Often the sections strung between risers aren't even connected to each other; they rely on their weight to stay put.

But earthquakes can make an elevated highway shimmy and shake. Sections can pop off their risers and plunge below. And the risers can collapse, bursting from internal pressures if they're twisted in place. Many have lost their lives when this happens, particularly in California.

Which brings us to Honolulu's highways. Although we're not a high-risk earthquake zone, it can happen. Over the last several years, at least 10 bridges have had "seismic refits" paid for by the Feds, and the Department of Transportation is working on the elevated portions of H-1.

This is largely accomplished in three ways:

A larger concrete pad is dug and poured around the base of the riser columns.
A kind of giant hinge is attached to the joint between the elevated section and the riser so it can slip apart.
A Teflon wrap is wound around the riser, like the skin of a sausage, to prevent "column bursting."

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