“Like pieces for a gigantic erector set,” thousands of steel beams, connectors, supports and fasteners have already arrived and are being assembled into a temporary bridge to replace the collapsed I-5 bridge over the Skagit River in Mount Vernon.
According to Bill Killeen, president of Acrow Corporation of America, the manufacturer of the bridge, about 20 truckloads of the silvery-gray hot-dipped galvanized steel are on site or on the way to Mount Vernon, as are Acrow construction specialists from Tampa, Fla., Vancouver, B.C. and Camas, Wash.
“We’ve built thousands of bridges around the world over the past 60 years, many of them under emergency conditions,” said Killeen, who noted that he personally worked with an Acrow Bridge team rebuilding more than 60 bridges around Mount St. Helens following the 1980 eruption.
The northern section of the bridge fell into the Skagit River, May 23, when a southbound Mullen Trucking Co. truck hauling a large housing for mining equipment clipped one or more load-bearing supporting struts as it crossed the bridge. The over-height truck was accompanied by a pilot car with a vertical measuring pole which, according to witnesses, also struck the bridge in front of the truck following behind.
Three people were rescued from two vehicles that plunged into the water along with the bridge. All three were unharmed and released from local hospitals after being checked out and warmed up.
Killeen said his company started loading trucks at marshaling yards near Acrow’s Parsippany, N.J., headquarters and at rented storage near Camas, Wash., less than 24 hours after the collapse. The trucks were dispatched immediately after contracts were signed, some with tandem crews driving day and night.
The two side-by-side temporary bridges will be assembled from “several thousand pre-fabricated modular pieces.”
Each bridge will measure 24 feet by 160 feet and weigh about 400,000 pounds when they are rolled into place from the still-standing south section of the bridge where the final assembly will take place.
Crews from Atkinson Construction and several Atkinson subcontractors are already working around the clock to assemble the two bridges. Both Acrow and Atkinson confirmed that the target for completion of the temporary project is mid-June – a timetable several weeks sooner than first estimated by state officials.
Total cost of the temporary and permanent bridges was estimated last week at $15 million, almost all from federal transportation funds. One million dollars was released almost immediately by federal officials according published reports.
The temporary bridges will each carry two lanes of traffic northbound and southbound and are designed to carry fully loaded I-5 trucks, although a Washington Department of Transportation spokesman said that DOT would probably limit trucks to less than 80,000 pounds maximum weight and keep speed limits below the present 60 miles-per-hour.
Still-standing parts of the bridge and supporting foundations have been inspected and cleared for continued use by a team of state and federal bridge inspectors and engineers.
DOT engineers are already at work assembling information and specifications to be used in designing the permanent replacement bridge. Travis Phelps of the Department of Transportation estimates that design options will be chosen in July followed by a competitive bidding process. Construction is expected to begin in August in the river next to the temporary structure.
Sometime in September, crews will remove the temporary bridges and move the new bridge into place from the side. Interstate 5 is expected to be closed for about two weeks in September during final construction.
