Salem Rivercrossing Traffic Modeling Discussed at Portland Talk Tomorrow

Let's go with the alternate title, shall we?

"Post-Apocalyptic Zombies Ate Oregon’s Post-Recession, ATR Regression."

All about post-apocalyptic zombies
(Mad Max, friends!)

Yeah, so what about that plateau in traffic counts and distance traveled?

via Washington State Ferries
Transportation Revenue Forecast, October 2014
(Sightline link broken)

Tomorrow at noon, Friday the 22nd, Andrew Mortensen of David Evans and Associates will talk at PSU about new Federal vehicle miles traveled forecasting and how this might impact local traffic planning.

A summary of FHWA’s new national traffic trends assessment will be presented, including discussion of varied factors influencing forward-thinking forecasts. Examples of Oregon statewide vehicle miles travelled (VMT) and historic traffic trends from ATR [automatic traffic recorder] stations in the Portland urban region and greater Willamette Valley will be highlighted. VMT, population and income data will be noted with implications on local transportation planning. [italics added]

Readers have suggested that we might read "greater Willamette Valley" as including "Center and Marion Street Bridges." (After the jump for updates!)


The talk should be webcast at noon, Friday the 22nd, and later archived, and you can stream it by the big button on the PSU site.

N3B's latest chart on the traffic counts

It seems doubtful that there would be any new data from actual counts. N3B has been scooping up and tabulating this faithfully!

But what could be very interesting are the "forward-thinking" conclusions the Federal Highway Administration might be drawing from the data.

It seems possible that realism might be starting to drive a wedge between Federal forecasting and our own local forecasting. A disjunction here could have implications for the adoption of the Final Environmental Impact Statement for the Salem River Crossing.

If you have an interest in the traffic modeling that theoretically and ostensibly underpins the "purpose and need" for the Salem River Crossing, this talk could be relevant and more than a little interesting.

Update, Saturday

Here's the video. Interestingly, the very first question afterwards in the Q&A seemed to elicit an answer that pretty much undermined the presentation.

In general terms Mortensen was making the case that the new FHWA estimate of 1.04% growth per year corresponded more closely than the 1990s-era estimated growth rates, which were much higher.

But Kelly Clifton of PSU asked him if he believed this. And Mortensen seemed to say, No, I have real doubts that even this growth at a lower estimate of 1.04% annually will continue.

Anyway. Here you go:


The slides alone are here.

Update 2

And here are a few relevant slides...

Here's our old friend, the crazy mismatches
between projection and actual

In the 2001 Recession, travel still grew (yellow),
but a structural change occured in 2005 or so

The difference between ODOT's 2005 projections
and the new FHWA 2014 projections

Placing the FHWA's new 2014 projection back to 1993
better describes reality. (See our bridges, lower right)

But again, in the Q&A Mortensen seemed to have doubts that even this new, lower projection of 1.04% annual growth would be sustained.

(There's a sense in which he's still constrained by prior commitment to growth, a prior that is largely independent of empirical data and best available information. The presentation and FHWA approach still lacks error bars and an expression of the statistical range of uncertainty.)

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Postscript - I should have included a citation to the FHWA's own projection. "FHWA Forecasts of Vehicle Miles Traveled (VMT): May 2014":

With this Baseline economic outlook, Table 1 shows that growth in total VMT by all types of vehicles is anticipated to average 1.04% annually over the next 20 years, and 0.75% annually over the next 30 years. This represents a significant slowdown from the growth in total VMT experienced over the past 30 years, which averaged 2.08% annually, although growth in motor vehicle travel was already slowing throughout most of that period.