Seattle probably used Kiewit to build part of their freeways, just as ODOT did. Recently, we discussed the role that an expanding expansion joint has played in numerous wrecks on the flyover ramp connecting I-5 north with highway 217, south of Portland.
It seems that the same issue's cropped up in Seattle, where a muti-vehicle wreck on I-5 yesterday morning brought the city to a halt.
An expansion joint is a gap between bridge spans, allowing the structures to expand and contract with temperature changes. Many are covered by steel plates to protect the joint from moisture or erosion.
The problem is that over time, vibration causes them to shift. Newer techniques use rubber or silicone fillers, eliminating the problem.
