Portfolio Update 2011
Stretching 175 feet above the Willamette River, the Fremont Bridge is a vital link for Interstate 405 which encircles downtown Portland, OR. I-405 is a heavily traveled loop that helps to ease congestion in and around the city center so construction activities affecting it must be scheduled to minimize the impact to motorists while ensuring the safety of the public and work crew. The Fremont upper deck paving project required full closures for 3 weekends (from 11 p.m. Friday to 5 a.m. Monday) and one weekend of partial closure -- it wasn't your average paving project!
The Fremont Bridge has an epoxy asphalt concrete surface -- it's the only bridge in Oregon with this type of pavement. After the project is finished, the upper deck will consist of 3 layers: a 1/2-inch-thick steel deck plate, 2 1/2 -inches of epoxy asphalt concrete, and 1 1/2-inches of conventional hot mix asphalt concrete. In total, more than 3,000 tons of epoxy asphalt and hot mix materials will be placed at a rate of 50 to 75 tons per hour. It's a time consuming and time sensitive process - and a demanding and interesting assignment to document too - so that's why I decided to present this photo essay as my Oregon Department of Transportation (ODOT) Portfolio Update for 2011.
Before the paving process can begin, all the old road surface must be removed. Chipping, grinding, scraping, tearing . . . all techniques need to be used to clear the bridge deck to bare steel. The hardest part had to be cleaning the big bolt heads . . . and there were about 56,000 of them!
Next, the deck is polished and primed by shot-blasting, or the rapid-fire bombardment of tiny steel shot against the deck surface to clean and rough it so materials will better adhere to it. Then the first epoxy bond coat is sprayed on the deck to coat the steel and prime it for the first lift of epoxy asphalt.
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