Bob Ortblad, a civil‑engineer with a Master of Science in Civil Engineering and an MBA, submitted a letter to the editor of Clark County Today raising concerns about the Interstate Bridge Replacement (IBR) program’s temporary diversion design. Ortblad, who lives in Seattle, Washington, used an artificial‑intelligence tool to model lane configurations and calculate safe speed limits for the proposed six‑lane, 76‑foot‑wide roadway that will carry both northbound and southbound traffic once the two existing bridges are closed in 2033.
AI‑generated speed recommendations
According to Ortblad’s AI analysis, a safe speed limit for passenger cars on the temporary diversion would be 30 mph under dry conditions, while trucks should be limited to 20 mph. When wind gusts reach 45 mph, the AI reduces the recommended speeds to 25 mph for cars and 15 mph for trucks. In heavy rain or icy conditions, the model suggests cars travel at a crawl of 5‑10 mph and that trucks be barred from the bridge entirely.
Design factors considered
The AI model incorporated several design variables, including a 1,510‑foot S‑curve with a 700‑foot offset, a straight‑line 500‑foot transition between curves, 6 % superelevation, a negative 3 % grade, 2‑foot shoulders, 12‑foot travel lanes, 45‑mph wind gusts, and frequent rain and ice. Ortblad argues that these inputs reflect the real‑world conditions the temporary bridge will face and that the resulting speed limits are conservative enough to protect motorists.
Call for independent safety review
Ortblad’s letter points out that Carly Francis, the IBR interim program administrator, has declined to allow Washington State Department of Transportation (WSDOT) and Oregon Department of Transportation (ODOT) safety engineers to conduct an independent safety analysis. Francis cited the Federal Highway Administration (FHWA) and Federal Transit Administration (FTA) reviews and the record of decision as providing “immunity” from further public safety questions.
Ortblad urges the IBR team to commission its own AI safety study for both the temporary diversion and the final bridge design. He believes that an independent, data‑driven assessment would address community concerns, improve public confidence, and ensure that the temporary structure meets the highest safety standards.
Why the issue matters to Clark County residents
The IBR project is a major infrastructure undertaking that will reshape traffic patterns across the Columbia River corridor. With the new southbound bridge slated for completion by 2033, the temporary diversion will be the sole crossing for all vehicular traffic for several years. Ensuring that lane allocations and speed limits are safe is essential for commuters, freight operators, and emergency responders who rely on the bridge daily.
Local stakeholders, including businesses that depend on timely deliveries and families who commute across the river, have expressed a desire for transparent safety evaluations. An AI‑based analysis, as demonstrated by Ortblad, offers a modern tool that can complement traditional engineering reviews and provide an additional layer of assurance.
Next steps
The IBR program has not yet responded publicly to Ortblad’s request. However, the letter underscores a broader call for accountability and data‑driven decision‑making in large‑scale public works projects. As the project moves forward, Clark County officials and the public will be watching closely to see whether an independent safety study is commissioned.
Community members who wish to stay informed about the IBR project can attend upcoming public meetings hosted by the IBR steering committee, where updates on design, construction timelines, and safety measures are typically shared.
Original reporting: Clark County Today (Vancouver WA) — read the source article.
