Calculations in question -New Numbers Suggest Some “Pro 3rd bridge” Assumptions Incorrect
Salem’s City Council is one of several entities now deciding whether to recommend that a certain ‘3rd bridge’ plan move forward. Their work is part of a complex process which may, in time, result in the construction of a new bridge across the Willamette between Salem and West Salem. But newly-released numbers suggest that some critical data being used by the City Council is outdated.
On January 2, the Oregon Office of Economic Analysis (OEA) issued a new draft document, a 2012 long-range forecast*, to all Oregon county officials. The draft document predicts significantly less growth for our area than previously expected. Recent analysis also suggests that traffic is decreasing in ways City Council’s figures do not reflect.
“The question of whether or not there is a need for this new bridge has to be answered by the facts that exist today,” says Eugene’s Mia Nelson, a real estate developer and construction contractor for 17-years who now represents 1000 Friends of Oregon, a non-profit organization focused on livability.
On January 4, Nelson wrote Salem’s Mayor Anna Peterson and the Salem City Council to advise them that population and traffic forecasts used by the group that has guided “Third Bridge” exploration since 2006 were based on older data that assumed higher growth in Polk County than the new OEA draft forecast.
“Is it really true,” Nelson wrote the City Council, “that bridge traffic will double in the next 18 years? If not, then the integrity of the decision-making process has been compromised, because that assumption was key to the determination that a third bridge was necessary.”
Population statistics used by the City Council thus far have relied on 2000 census and 2004 OEA projections, Nelson says. The calculations predicted, for example, that afternoon peak period traffic across the Willamette between Salem and West Salem would double by 2031.
In fact, however, current bridge traffic levels are already 25% lower than those forecast for 2015.
Faulty assumptions, Nelson wrote in her letter to the Council, raise the risk of a bad decision. “Wrong inputs yield wrong outputs.”
When she spoke to Salem Weekly, Nelson said, “Population growth predicted by the 2004 figures [currently used by the City Council] is almost 50% higher than the new OEA draft. That’s not a solid basis for a project this large.”
At Seattle’s Sightline Institute, an organization dedicated to “Smart Solutions for a Sustainable Northwest,” researcher Clark Williams-Derry has been studying traffic trends for more than a year. Williams-Derry says that assumptions the city has made about vehicle traffic are also obsolete.
“I’ve been exploring the fact that traffic volumes in Oregon and Washington have generally been flat or perhaps declining for about a decade,” he told us. “The trends predated the recession, which started in 2008 or so. The flat-lining of traffic is apparent at all sorts of different levels.”
Williams-Derry’s August 2012 article on Sightline’s website tallies up vehicle travel on state, county, and local roads. It says, “Northwesterners have aggressively reduced their use of motor fuel. Last year, per capita combustion of gasoline in Oregon fell to its lowest level since 1962—back when a gallon of gasoline cost 31 cent.”
The total vehicle miles travelled on Oregon’s highways have decreased over the last decade despite an 11% increase in Oregon population.
Williams-Derry cites declines in driving, especially among northwesterners under the age of 35 and says that driving, economic and demographic trends, “… all point towards continued declines in gasoline use in the Pacific Northwest.”
In her letter to Salem City Council, Nelson mentioned Sightline research as well as the updated 2012 OEA population projections.
“Prior to committing public funds to a new bridge project,” she concluded, “the city should exercise due diligence and determine the likelihood that planning models overestimate future bridge traffic and toll revenues…to protect the city from unexpected revenue shortfalls.”
As of print time, Salem Weekly did not have time to obtain reactions from the City Council about Nelson’s letter.
Because pro-bridge advocates do not consider growing population and traffic to be the only arguments in favor of construction (see our article of December, 12, 2012, “Why Build a Third Bridge?”) the impact of the new OEA and Sightline statistics has yet to be seen.
* The draft OEA forecast has not yet undergone a required comment period and review. The final version will probably be released in February.