The four-day closure of Interstate 90 at Snoqualmie Pass last winter cost the state 170 jobs and the loss of $27.9 million in economic output, $1.42 million in state revenue, and $8.6 million in personal income, a Washington state Department of Transportation study says.

DOT closed I-90 at Snoqualmie Pass on Jan. 29 for avalanche control, then reopened the highway the next day. Four hours later, a second avalanche slammed it shut.

I-90 remained closed at the pass for almost four days, until Jan. 2, as record snow and warm temperatures continued to pose danger from avalanches. In those four days, the important east-west corridor, which carries 6,500 trucks a day—some hauling shipments of Eastern Washington produce and medical supplies for Spokane hospitals—was closed for a total of 89 hours.

For six days in all, DOT crews worked around the clock to clear the highway of snow and to deter further avalanches, pushing road-clearing expenses $9.1 million over budget, DOT says.

To analyze the economic impact of the closure, and also the economic impact from the four-day closure of Interstate 5 in December due to severe flooding, DOT surveyed nearly 2,800 freight-dependent and trucking industry businesses, or 58 percent of all businesses in those sectors in the state. From the survey results, it obtained estimates of business losses suffered because of the closures, of direct economic impacts on those sectors, and of total economic impacts in the state. DOT plugged the survey results into the state's economic input-output computer model, which estimated the ripple effects of the closures on the economy.

The economic pain from the I-5 flooding was even sharper than that from the I-90 avalanches. The DOT report says the I-5 closure cost the state $47 million in economic output, 290 jobs in the following year, $2.4 million in state revenue, and $14.6 million in personal income.

The study recommended that the state provide more support and investment for maintenance along that stretch of highway and also said the state needed to build a safer mountain pass route on I-90.

DOT has been working for years to plan and design improvements to Snoqualmie Pass, and in 2009 it will launch the $545 million first phase of that work, in a five-mile stretch of I-90 between the community of Hyak and the southern end of Keechelus Lake.

"We just issued the final EIS (environmental impact statement) on the project and the record of decision last month," says project director Randy Giles, an engineer in DOT's south central regional office in Yakima. In February, DOT will advertise for bids for the first contract on the project, and construction under that contract will begin next spring, he says. Then, late next year, DOT will seek bids on a heavy construction part of the first phase, and that work will start in the spring of 2010, Giles says.

It could take six or seven years to complete the first phase of the work, he says.

"We've got a lot of challenges, a lot of risk, a lot of unknowns," he says. "We're building a six-lane road between a rock face and a lake. We've got to maintain traffic. We're going to do a lot of blasting. We'll have to work during windows when the weather is good. We could have a flood year."

The project will widen I-90 there to six lanes from four and will realign part of the route, Giles says. It also will replace or reconstruct a snow shed that carries snow above the level of the highway when avalanches thunder down. The 40- to 50-year-old pavement will be replaced, and other improvements will be constructed, including bridges at three creeks, larger culverts at three others, wildlife crossings, avalanche fences, and expanded areas for drivers to put on and take off tire chains.

Originally, the project was to have involved constructing lengthy bridges over Keechelus Lake to move the part of the roadway that's covered by the snowshed out over the lake. The idea was that snow from avalanches would spread out under the bridges rather than blocking the highway, but Giles says an avalanche safety expert who consulted with DOT on the plan said it was hard to predict how big avalanches might be and whether the bridge would have enough clearance beneath it to handle all of the snow that might come down the mountain.

Also, avalanches produce an enormous amount of powder snow just above the mass of cascading snow, which could have caused a whiteout on the highway, leaving drivers with no visibility, Giles says. Moreover, avalanches cause air pressure immediately above them to increase markedly, which might have exerted force on moving vehicles, making them difficult to control, he says.

DOT decided to alter the project, although "we are going to push into the lake in some places" with parts of the roadway, he says. Giles says DOT also will "push into the hillside" to make space needed to widen the highway and will do a considerable amount of work to stabilize what has been an unstable slope on the uphill side of the highway.

The project will be paid for with money from the 2005 Transportation Partnership Program, through which the Washington Legislature approved four sources of increased transportation revenue, including $5.5 billion from a 9.5 cents per gallon gasoline tax increase to be phased in over four years; $908 million from a vehicle weight fee on passenger cars; $436 million from a light-truck weight fee increase; and an annual motor home fee of $75.

Initially, the Legislature approved the first phase of the Snoqualmie Pass work in 2005 as a $388 million project, but inflation in construction costs has pushed up estimates, and lawmakers reapproved it as a $545 million project last session, Giles says. The project will include some follow-up contracts, he says. A second phase of improvements near Snoqualmie Pass is planned between the south end of Keechelus Lake and the town of Easton, about 10 miles to the southeast. It has not been funded.

DOT says that over the last decade, I-90 has been closed in the Snoqualmie Pass area an average of 29 times each winter.

"We're not going to eliminate closures," even with the extensive work that will be done, because "the weather can sock it to us," Giles says. "We're going to make it easier to keep the road open, and we're going to get rid of some of these problem areas." Avalanches still can "cluster" to the west of the project area and close I-90 there, he says.

Part of the problem in the closure last winter was that rough weather also pounded alternate routes, DOT says. Winds of more than 100 miles an hour and near-record snowfall of 605 inches slammed Stevens Pass, and U.S. 2 was closed there for 82 hours in January and February. At White Pass, on U.S. 12, 267 inches of snow fell in a 16-day period, including 78 inches in 48 hours, and several avalanches hammered the route, including one that left 20 feet of snow on the highway. White Pass was closed for 59 hours in one three-day period.

With most of the state's east-west routes also closed when Snoqualmie Pass was shut down, truckers were left with few options, DOT says. It says it recommended that westbound truckers detour from Snoqualmie Pass to take Interstate 82 south to Interstate 84 in Oregon, and eastbound drivers had the option of using I-84, but severe weather also closed that highway, cutting off all east-west detour routes for a time.

The Snoqualmie Pass closure cost the Walla Walla Gardeners Association six truckloads—or $70,000 to $150,000—in lost sales to family farms when deliveries of fresh produce couldn't be made to Seattle-area grocery stores, DOT says.

The study says DOT communicated with businesses and communities during and after both the Snoqualmie Pass and I-5 closures to provide timely and accurate information to the freight industry. It developed a freight e-mail list and sent several messages—called "truck stops"—with updates on road conditions, provided information to trucking channels on satellite radio, distributed flyers and detour maps directly to truck drivers, and updated its Web site with alternate truck routes. The study says DOT could upgrade its information-technology system to improve communication, provide even more timely and predictive information, and provide more roadside cameras that show real-time views of the highway.

Some of that will be done in the project at Snoqualmie, and other work will be done outside of that project, Giles says.

"We are looking hard at providing people with decision-making information before they get up to the pass," he says.