Question: Why is it okay to change lanes on the eastbound Tacoma Narrows bridge and not okay to change lanes on the westbound bridge?
Answer: According to Claudia Bingham Baker, communications manager for the Washington State Department of Transportations Olympic Region, its because of the steel grates that separate the lanes on the westbound bridge.
When engineers designed the bridge in the late 1940s, they put in the grates to let wind pass through rather than over the bridge, thinking it would reduce the lifting effect that helped destroy the first Narrows Bridge Galloping Gertie.
Designers of the new (eastbound) bridge decided that precaution was not necessary.
The grates are made of steel and tend to get slick when wet, Bingham Baker said. The restriction is in place to ensure people have traction when driving across the bridge.
Before the 2007 bridge was built, the no-lane-change restriction was in effect in both directions of State Route 16 because both eastbound and westbound traffic were driving across the 1950 bridge, Bingham Baker said.
The 2007 bridge deck doesnt have grates, she said, so eastbound state Route 16 traffic using the new bridge may change lanes on the bridge deck.
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