Thursday, March 13, 2014

Traffic Cameras Offer Pictures of Actual Congestion on Bridges - Hint: Maybe Not Much!

Oh, boy. It looks like the paper is going to use the new traffic camera information to write "traffic jam" stories.

Story posted at 5:09pm - the image is not timestamped, however
Late yesterday afternoon they posted a teaser story, "Traffic slow near Marion Street Bridge." Only problem is, a single image of "congestion" doesn't say anything about actual delay, about the dimension of time. Basing a whole narrative on a thin slice isn't sound.

Based on a few more snaps, though, it hardly looks like the bridge is actually congested!

(And you have to wonder if pro-bridge advocates are trying to "seed" a story about outrageous congestion. On an email list there's a note about a phone survey going around right now that asks about the Third Bridge, police station and City Hall, the Mayor and Council, and a few other things. The coincidence makes you go hmmm a little...)

5:18pm - two approach lanes have gaps, bridge itself not congested
(all clips from the City traffic camera page)
In any event, between 5:18 and 5:30pm the bridge and its approaches were not congested this that same evening.

5:23pm - all  three approach lanes have gaps; bridge also

5:26pm - two lanes with short queue; bridge not congested

5:30pm - gaps in all three approach lanes; bridge not full
There wasn't time to make more than a few snaps between 5:15 and 5:30. Maybe more another time, or maybe you will be able to squeeze in some viewing. Monitoring a camera for a full hour or two could make an excellent citizen science project - more actual data! - and likely provide strong visual evidence that congestion isn't as bad as people think it is.

Interestingly, a later, edited version of the story - turns out the paper doesn't timestamp updates or otherwise signal edits - indicated there was a crash and a tow-truck at the time the story was written. (Maybe the story has less nefarious origins in scanner traffic or something - still, it's easy to see a conspiracy with regard to the plot for a third bridge!)

So the queuing and spacing we see here could even have taken place while traffic flow was still potentially altered by the crash or crash clean up.

Though 15 minutes of traffic camera clips aren't determinative, it's still really hard to square these images with the popular perception of gridlock, congestion, and intolerable waiting.


Laurie Dougherty said...

I know ramps go off in various directions, so you have to be on where you want to get off, but could there be room for a combined HOV and bus lane?

Salem Breakfast on Bikes said...

There was one alternative called the "Brown Alternative" that was for converting both of the existing bridges to two-way traffic. You could have flexible lane configurations, even HOV lanes that shift direction for the am/pm commute. Surely reconfiguring the existing ramp spaghetti would be cheaper than a new bridge!

It has seemed to me that this would be an excellent way to use existing capacity and the Brown Alternative probably deserves more attention now. Unfortunately it was ruled out very early in the process, and I can't find a picture of it, a description of it, or more than a summary for why it was dismissed.

(The SRC revamped the website, and there's a fair bit of linkrot and inaccessible documents now.)

Jim Scheppke said...

Great post, SBOB! Thanks. As for the conversation you are having with Laurie, I don't know about the Brown Alternative, but the 1998 Bridgehead Engineering Study had lots of good ways to fix the ends of the existing bridges to make traffic flow better. Most were never built. Instead the plan was shelved in 2006 when the Salem River Crossing project began with the clear intent of building a 3rd bridge. But even in the course of that project, Alternative 2A was developed to add three new lanes to the existing bridges at a cost of around $150 million. If the City is determined to finish up the SRC project and get a Final Environmental Impact Statement done, in case we might need it someday, they ought to go back to 2A as the best of the build alternatives that the SRC Task Force came up with.

Salem Breakfast on Bikes said...

Well, you may be right that 2A is "the best of the build alternatives" that were in the DEIS, but it's difficult to share your enthusiasm for it, as it is still an auto capacity expansion and would remove a key bike/walk connection. It is a solution whose diagnosis is that "we still need to increase auto capacity and there are cheaper ways to do it than a super expensive new bridge."

The position here is that we don't need new auto lanes and instead we need to use our existing capacity more wisely and effectively. And perhaps even more importantly, that the costs - financial, social, and environmental - of increasing auto capacity are so great, that even if we thought it was necessary, we should do all we can in our power can avoid it, and if it comes down to it, refuse to do it.

Additionally, between 4(f) considerations - protections for parks and history - and other factors, a person from ODOT had mentioned at the Historic Landmarks Commission a couple of years ago that the 2A bridge design did not meet Federal requirements to move forward. (This could be true for the Brown Alternative as well.) My sense was the State Historic Preservation Office and allies would get involved to a much greater degree if the tide turned towards 2A.

So here, anyway, there won't be any pivot to support 2A. If there's a "sanctioned" part of the Rivercrossing process to support, it is the Alternate Modes Study, and its recommendations are what seem worth pursuing.

Salem Breakfast on Bikes said...

Re: The very kind N3B note:

"The Statesman Journal had a story about afternoon congestion on the Marion St. bridge with the picture below. Turns out there was a wreck that caused the problem, and this was not normal congestion. Our intrepid Breakfast on Bikes blogger took snaps the next day beginning at 5:18 p.m. and found no peak hour congestion downtown."

Actually, this was not the next day, but the very same day, just a half hour or hour after the crash!