The hugeasscity blog got more details out of the Seattle Department of Transportation regarding their plans for 23rd Ave and the possible installation of bike lanes per the Bike Master Plan.
The short story is that the city will begin detailed traffic analysis of 23rd starting this fall, with a goal of making a final decision by March 2009.
The city also says that they invite community involvement in the process, so if you’ve got an opinion, tell them all about it at:
http://www.seattle.gov/transportation/citizen_response.htm
So if the city decides to add bike plans on 23rd, thereby reducing auto traffic to one lane each way, while acknowledging that 23rd is a major traffic arterial, where will the squeezed-out car traffic go?
Evidently the city data shows that there’s 2-lane roadways that carry more traffic than 23rd:
http://www.centraldistrictnews.com/2008/02/25/dear–3rd-ave-youre-too-skinny-and-need-a-diet
But, I think it’s reasonable to expect that a 2-lane 23rd would incur some backups at peak hours. Of course it’s not a perfect situation now, since buses and left-turning cars routinely block one lane of the street. Ideally, a center turn lane and the margin of the bike lane would keep traffic flowing more smoothly in the main traffic lanes than in the current configuration.
That’s the kind of things that the city’s engineers will look at as part of their analysis.
It’s been shown in many other cases that replacing a four-lane section with a 3-lane section with a center turn lane actually results in about the same or even higher vehicle throughput because of what Scott pointed out — you don’t get traffic backing up with cars waiting to turn left. You also avoid the safety issues of frustrated drivers suddenly changing lanes when they get stuck behind a left turner.
There’s a good downloadable paper on road diets by walkable communities advocate Dan Burden and City of Seattle bike guru Pete Lagerwey here:
http://www.walkable.org/download/rdiets.pdf
i’m not sure the city can actually do this. I’m guessing 2009 is more like 2010 and maybe 2011 (see Stoneway).
btw, i drive pretty regularly on both MLK and 23rd (during Peak Hours) and I am dubious about the numbers being equal.
2 lanes would definitely add a more friendly feeling to the neighborhood ambiance
Joanna.
I frequently use the bus stop that is on the east side of 23rd near the church parking lot and just a tad south of the big Safeway near Madison. It can be positively terrifying to stand there waiting for a bus as cars and trucks speed by within a few feet of where I’m standing. I’ve seen situations where it is physically impossible for two trucks (of the size that deliver goods to the Safeway) headed the same direction to fit in the lanes; the street is too narrow. If the traffic flow numbers are even close between a diet or no-diet 23rd, I say go with the diet solution and make the street friendlier and safer for pedestrians, bus riders, and bicyclists, thereby encouraging more folks to get out of their cars and use these other forms of transportation.
You’re right about the trucks! Then the truck in the inside lane swings to the left, crossing the center line, and endangers oncoming traffic. It’s very scary!