| Working the angles: moving large freight through work zones |
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Pilot cars escorted dam spillway doors through work zones
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Working the angles in work zones: moving large freight through tight situations
Oregon's dramatic topography makes it a hotspot for outdoor enthusiasts and camera buffs, but its steep mountain inclines and winding back roads can be daunting, especially for tractor trailers hauling oversize freight. Constricted bridge construction zones add to the challenge.
Through careful planning, coordination and teamwork, mobility experts from the Oregon Department of Transportation's Major Projects Branch and Motor Carrier Transportation Division have made way for many varieties of massive cargo in recent years: steel doors for dams on the Columbia River, supersize mining dump trucks, and the casting mold for wings on heavy-duty military aircraft.
"We have 16 analysts who stay busy issuing permits every day," said Christy Jordan, over-dimension permit unit and freight mobility manager in the MCTD. "Because of the amount of coordination these special shipments require with district managers all along the route, the analysts take turns working on the permits for super-loads."
Accommodations in the traffic control plans can include rerouting on county roads, to avoid work zones, and what MCTD calls "up and overs": avoiding a low-hanging overpass by sending a truck up and down the off- and on-ramps alongside a roadway. District managers are united in one desire: They all prefer that oversize shipments pass through their area during the quiet, early-morning hours.
This year, one unusual supersize load has been the replacements for the downstream locks gates at the John Day, The Dalles and Lower Monumental dams. The Columbia River Gorge was not only the shipping corridor but the destination for the gates, which range in size from 350 to 1,000 tons and passed through six ODOT work zones on Interstate 84, where 10 bridges have been under construction. To install the gates, the U.S. Army Corps of Engineers will close the Columbia River to all barge traffic from December 2010 to March 2011. Incidentally, I-84 will see increased freight transport as the petroleum and wheat that move by the river go by road instead.
I-84 through the Columbia River Gorge was the site of another occasion for special treatment of oversize freight. Six mining dump trucks — each more than 20 feet wide — were being sent from Portland to Montana.
"We took advantage of a window of opportunity," said Randal Thomas, ODOT statewide traffic mobility manager, "moving the trucks through the Gorge individually over a seven-to-10 day period to avoid work zone lane closures."
One of the craftiest solutions to a mobility conundrum occurred when it looked as though an enormous mold for casting the wings of military aircraft would remain stalled at the Oregon border. When it left Interstate 82 in Washington state headed east on I-84 through Oregon, the load would run into an active bridge construction zone in Lime, east of La Grande.
"The dimensions of this cargo were substantial — 85 feet long and tapering from eight to 21 feet wide," Thomas said. "It was too big to travel on the alternate, secondary routes of U.S. 97 and U.S. 20, so I-84 was the only option."
ODOT mobility team members went out to the site, hand-measured the clearances and determined that the load would in fact vertically clear the 50-inch medians in the work zone. But the wing would extend into the westbound lane on the other side, so the team set up a rolling closure whereby oncoming traffic was slowed to approximately 35 miles per hour while the wing passed through the work zone on the other side. Contractors are used to managing rolling slow downs because they use them when they need to swing beams by crane carefully over an active roadway.
"Maintaining freight mobility is a major goal for ODOT because the free movement of traffic is essential to our economy," Thomas said. "As loads have gotten larger—both taller and wider—we’ve stepped up our creativity and ingenuity to make sure we stay on top of the situation."
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