October 29, 2024

The Dangers of Heavy Precipitation over Local Roadways

On Sunday, the substantial dangers of localized heavy precipitation for highway travel were made clear.  In this blog, I will describe what happened and suggest steps you can take to stay safe.

The first situation occurred Sunday morning on I5 near Bellingham after heavy overnight rain.   A mudslide pushed over the roadway, trapping a truck and closing the freeway for 10 hours (see picture below).


Then around 1:40 PM, after the passage of a band of heavy showers, there was a blinding reflection of sunlight on a wet I-5 near Kent, resulting in a mass collision on the freeway encompassing 45 cars.

You read that right:  45 vehicles were smashed up and the road was closed for hours (proof below).


The first question that most of you must have is this:  how much rain fell during the event on Sunday?

The totals for Saturday and Sunday are shown below. Over two inches(2.12 inches) at the Bellingham Airport and as much as 5 inches over the western slopes of the Cascades.  Roughly an inch around Kent.


The 2.12 inches in Bellingham broke the daily record and was the 18th heaviest day over the entire record (going back to 1949). A culvert was blocked by a roll of carpet padding, leading to the failure of the adjacent slope.  

The Kent accident cases were more interesting.....and much more avoidable.

The radar image a few minutes before the accident (1:02 PM, 10/27 showed a band of moderate showers ( yellow colors) over the roadway.


As shown by the visible satellite image at 1:16 PM, the band had moved east and most of the clouds were gone, allowing sunshine on the roadway.  


So what happened?   Keep in mind the southbound I5 had the problem--the direction heading towards the sun.  There were several reports of substantial glare on the roadway.

The classic situation is that a pack of cars is traveling too fast for wet conditions and far too close.   One driver is blinded by the glare and slows abruptly, starting a chain reaction collision with the cars behind him/her.  

I suspect this is what happened in this case.  The other familiar failure mode is when one car enters heavy rain and rapidly slows down, resulting in a chain of collisions of the cars behind them.  Dust storms and fog can do the same thing.

The advice is clear.  During rainy conditions slow down and leave substantial room between you and the car in front of you.





11 comments:

  1. I can tell you this...I have been driving for 60 years in the NW...and have noticed, that your sage, obvious advice about slowing down, leaving more space between cars, etc. is being ignored more and more...we have of course, more and more vehicles on the road to contend with, and our various freeways can no longer handle the extreme volumes of traffic I see now. The situation is grim, and similar to the mess that traffic has been for many years, in California.

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  2. "A culvert was blocked by a roll of carpet padding, leading to the failure of the adjacent slope." I'm sorry, but I must be missing something within the context here. The only thing causing this flooding was a roll of carpet padding? I've heard of poor infrastructure, but this seems out of pocket.

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    1. Is this something that blew out of the bed of a truck on the freeway or something that rolled into a culvert from somebody's backyard?

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  3. I wear light colors, polarized sunglasses, even in the rain. And the next time you find Squint Busters at a fair or festival by you he has just the sunglasses you need.

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  4. A mass collision caused by sunshine - only in the Pacific Northwest ;).

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  5. I use wet traction tires on my car. These stick to the road like glue, but don't last as long, maybe 35,000 miles or so before the tires wear down to a point where I don't want to risk not having enough tread depth. The car is now fifteen years old, it is fully depreciated, and it refuses to wear out. So what I save in car payments goes to things like new tires every three or four years.

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  6. Ok my pet peeve.. there are too may large trucks around. There has always been some, but they were few and far between. They are everywhere now. They have taken to the 2 lane highways and even park on the side streets. They are a nuisance and are giant lumbering obstacles on the highways. They also tear up the road surfaces something awful. What a scourge, thanks a lot Amazon!

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    1. You may be partially right, but every single thing that we buy as a consumer had a ride in one of those trucks at some point. Our population growth has far exceeded the capacity of our roads, and truck traffic will rise proportionately with consumer demand and population growth. The only way to reduce truck traffic is for people to stop buying things.

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    2. What does this have to do with the article?

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  7. Coming home today from Seattle area to Kitsap County, the rain was about as bad as I have seen since I bought a car with current ADAS a year ago. Traffic slowed to about 5 mph less than speed limit. Between ADAS, being careful, and all of us slowing down it was an easy and not stressful drive home. Maybe 5 minutes extra time to be careful. Two cars weren't, saw them in a ditch near the Tacoma Narrows Bridge.

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  8. About 5 years ago I was driving a new "loaner" auto, with advanced driver assistance systems {I think} that cut the gas flow when a burst of rain hit the windshield. I guess I was a second slow in turning on the wipers. I was startled to have that happen. There was no one behind or in front of me so there were no crashes. I felt the ADAS reaction time was too quick.

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Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

The Dangers of Heavy Precipitation over Local Roadways

On Sunday, the substantial dangers of localized heavy precipitation for highway travel were made clear.  In this blog, I will describe what ...