Item: I-90 SNOQUALMIE PASS: IMPROVED HIGHWAY AVALANCHE SAFETY AND SUSTAINABILITY
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Title: I-90 SNOQUALMIE PASS: IMPROVED HIGHWAY AVALANCHE SAFETY AND SUSTAINABILITY
Proceedings: International Snow Science Workshop Proceedings 2023, Bend, Oregon
Authors:
- John Stimberis [ Washington State Department of Transportation ]
Date: 2023-10-08
Abstract: Interstate 90 (I-90) in Washington State, USA, provides a critical east-west transportation route connecting the ports and people of Western WA with the northern tier of the United States. The highway encounters the Cascade Mountains approximately 55 kilometers east of Seattle, WA, eventually crossing Snoqualmie Pass (921 m) and descending into Central Washington. Average daily traffic (ADT) over Snoqualmie Pass averages 30,000 vehicles per day, reaching peaks of nearly 50,000, with a significant percentage as commercial traffic. The heavy reliance on I-90 for these modes of travel represents a sizeable economic impact when the highway closes, even temporarily. Approximately 30 avalanche paths affect the highway around the Snoqualmie Pass area and historically resulted in numerous avalanche-related closures each winter, causing hundreds of hours of delays and related economic loss to highway travelers and regional businesses. To reduce these closures, the Washington State Department of Transportation (WSDOT) embarked on a multi-phase project to improve I-90 over the Snoqualmie Pass area starting in 2009. Two previous papers documented the planning process and operational challenges related to constructing twin avalanche bridges and 1500 meters of snow fencing within active avalanche areas (Stimberis 2012 & 2016). In this final paper related to the highway project and avalanche protection, the author reviews the performance of the avalanche bridges over the seven operational winters following the completion of construction. Most notable is the elimination of over 100 avalanche closures during this period, resulting in improved highway safety, reduced economic impact, and decreased emissions from idling vehicles.
Object ID: ISSW2023_O14.02.pdf
Language of Article: English
Presenter(s): John Stimberis
Keywords: avalanche control, highways, avalanche forecasting, avalanche defense, sustainability
Page Number(s): 1189 - 1192
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