Categories: all aviation Building a Biplane bicycle gadgets misc motorcycle theater
This is a local post, so if you're not from the Seattle area, it may not make too much sense. Sorry about that.
If you do live in Seattle, hoo boy. Be ready for some nasty traffic.
I-5 northbound is closing down to one lane, just south of the I-90 interchange. It's closing for 20 days, more or less. You can read more about it on this WSDOT page.
Now comes the fun part. 405 is also undergoing construction during this time, so it's gonna be packed. Most people will either take 405 if they need to go all the way north, or they'll take 99 if their destination is closer to Seattle.
Only, the northbound deck of the Alaskan Way Viaduct rates 9% on the same scale used to give the collapsed I-35W bridge in Minnesota a 50, according to this nationalbridges.com entry. So, the huge mass of traffic that normally takes I-5 has to go somewhere, and probably 50% of it is going to try cramming onto 99.
According to this page, there are 1663 vehicles per general purpose lane per hour, and 1230 vehicles per HOV lane per hour during the morning peak on I-5 at Corson Avenue, which is about where they're doing the construction. There are 4 normal lanes at Corson (roughly -- there's actually an onramp and an exit lane as well, but let's ignore those to keep the math realistic), and an HOV lane. So that's 7882 vehicles per hour across that section of I-5 north.
Then, according to this story, the Alaskan Way Viaduct (the excitingly dangerous 9%-rated part of Highway 99 that traverses downtown Seattle) carries 9000 vehicles per hour at peak. It doesn't specify whether that's one direction or both, so for the sake of argument let's say it's both directions. That means that northbound traffic on the viaduct is at least half that number, probably more like 2/3. Let's call it 6000 vehicles in the morning going north, for the sake of moderately realistic numbers.
So, we have 6000 vehicles per hour going north on 99, normally. We have 7882 vehicles per hour going north on I-5. Roughly half the traffic from I-5 should be spilling over onto 99; call it 3900 vehicles per hour during the peak. That's roughly another 2/3 more traffic than the viaduct sees now, for a total of 9900 vehicles per hour during the morning peak.
I don't know about you, but that sounds like an unwise burden on a bridge that's ranked in the 9th percentile. Because, of course, all those cars will be getting on the viaduct and parking, since it can't possibly carry that kind of capacity. Oh, but they'll move occasionally, just to make sure that they continue being a "live load" instead of a static load (dynamic loads are much harder on bridges than static loads).
Sounds like a pretty grim scenario to me. I'm not looking forward to the death toll when that bridge takes a dive mid next week. Thanks for the indecision, Seattle voters and politicians!
Posted at 11:03 permanent link category: /misc
Categories: all aviation Building a Biplane bicycle gadgets misc motorcycle theater