Portland economist Joe Cortright has taken a hard look (PDF) at a February tolling study produced for the $3.4 billion Columbia River Crossing Project by the consulting firm CDM Smith. Cortright findings cast further doubt on the assumptions about traffic volumes over the proposed new bridge and the tolling revenue that is supposed to provide the biggest portion of the project's financing.

Here's a summary of Cortright's findings:

Up to half of all current users of the I-5 bridges will divert to other routes when the bridges are tolled, according to the preliminary traffic estimates prepared as part of the CRC “investment grade” analysis by consulting firm CDM Smith.

These users will divert to other routes–probably clogging traffic on I-205, I-84 and SR 14, and delaying travel to and from Portland International Airport—but the CDM Smith report doesn’t address how traffic will be affected on these arterials. In 2030, according to CDM Smith, it is most likely fewer vehicles will use the new $3.4 billion I-5 bridges than use it today. These new traffic forecasts contradict the forecasts the CRC has been using for several years, and invalidate the analysis contained in the project’s environmental impact statement.

As WW reported last year, tolling on for a new bridge project near Seattle caused a more than 30 percent diversion in traffic.

Cortright prepared his tolling analysis for Plaid Pantry, which opposes construction of the CRC project. His previous criticism of the traffic and revenue estimates produced by the CRC project was validated by independent studies commissioned by State Treasurer Ted Wheeler.