Chief
01-25-2008, 01:39 PM
Bathymetric Imaging Survey of the Interstate Bridges (http://www.clarkblog.org/docs/Bathymetric Survey.JPG?s=&showtopic=4351&view=findpost&p=28980)
What you are looking at is a sonar-like image of the existing Interstate Bridges from approximately 2005. It is color coded to reflect the differing depths around the bridge supports in the Columbia River and in the slough. Red is the shallowest, and dark blue indicates the deep parts. The right side of the image is Vancouver, Hayden Island is in the middle, and North Portland is on the far left.
You can easily see the piers in the water of the river, and please notice toward the top (downstream side) of those piers, the deep scour holes around the piers. This represents holes that are literally deeper than the navigation channel in the main part of the river. This condition is one of the major liabilities of the Interstate Bridges, and contributes to the likelyhood of pier failure during a seismic event.
What you are looking at is a sonar-like image of the existing Interstate Bridges from approximately 2005. It is color coded to reflect the differing depths around the bridge supports in the Columbia River and in the slough. Red is the shallowest, and dark blue indicates the deep parts. The right side of the image is Vancouver, Hayden Island is in the middle, and North Portland is on the far left.
You can easily see the piers in the water of the river, and please notice toward the top (downstream side) of those piers, the deep scour holes around the piers. This represents holes that are literally deeper than the navigation channel in the main part of the river. This condition is one of the major liabilities of the Interstate Bridges, and contributes to the likelyhood of pier failure during a seismic event.