neighbors4a-bettercrossing.org
NEIGHBORS FOR A BETTER CROSSING IS AN OREGON NON-PROFIT
IBR DESIGN FLAWS
Just Crossing Alliance and its endorsing partners have generated a wealth of information that raise serious questions about the current IBR designs. The following are links to JCA’s website & design issues, and a 2003 report by Malcolm Drilling Company about unsuitable drilling conditions for the IBR bridge pilings!
The deadline for filing a comment with the IBR has passed, however it’s just the beginning of an effort to let our elected officials know we are opposed to the “Monster Bridge” designs proposed by the IBR project!
2013 Report by Malcolm Drilling Company about unfavorable drilling conditions where the IBR needs to drill!
2013 Foundation Drilling CRC
The Interstate bridge is in the Cascade Subduction Zone (CSZ), and a major earthquake is due anytime. The IBR bridge designs are not engineered to survive such a quake.
The area shown in red from Portland to Vancouver to the Columbia River Gorge at risk from soil liquefaction during a moderate to major earthquake, is shown in red in the diagram below, compiled by Multnomah County emergency managers in 2023.
For this month’s report, Multnomah County emergency managers assessed other high-risk industrial facilities in the county, many of which are concentrated in North Portland near the convergence of the Willamette and Columbia rivers. That area is also the most vulnerable to destruction resulting from liquefaction. That’s when earthquake shaking breaks up the soil near bodies fo water, creating a quicksand effect that can compromise above-ground storage tanks containing fuels and chemicals.
A major issue for the US Coast Guard and for commercial vessels is the IBR’s single or double-deck fixed-spans would have only 116 feet of vertical clearance above the water instead of the 178 ft clearance the current drawbridge offers. That’s a full 62 ft less clearance for vessels currently using the existing I-5 bridge today! A bridge report concludes that a 116 ft clearance limitation will permanently prevent vessels with (vertical navigation clearance) requirements of greater than 116 feet [clearance above the river] from transiting under the IBR bridge for its 100+ year service life,” per the Washington State Standard.