Posted by Michael Andersen (News Editor) on September 12th, 2013 at 1:36 pm
A state memo that dismissed a set of bike safety improvements on Southwest Barbur Boulevard was “wrong” in its use of traffic data, a traffic engineer who helped prepare the data said Wednesday.
Barbur, the only flat and direct route connecting much of Southwest Portland and the rest of the city, currently forces cars and bicycles to merge into the same 45 mph lane in order to cross two narrow bridges. The Oregon Department of Transportation has been under pressure from some nearby residents to explain its unwillingness to restripe the road after a planned repaving job.
As part of its case against replacing one of two northbound auto lanes with two dedicated bike lanes across the bridges, ODOT had cited a report finding that the change might increase travel times somewhere between 10 and 65 percent on the corridor by 2035. (It comes to something like 84 seconds to 9 minutes of additional auto travel time over the course of the 4.9 miles south of the proposed changes.) Among other things, the models assume that no one will ever change their schedule or mode of travel to avoid that congestion.
But Anthony Buczek, a traffic engineer for regional agency Metro who’s participated in months of negotiations over ways to change the road, said in an interview that those numbers were not the best available and said the two agencies had previously agreed not to release them without agreeing on how to correct their inaccuracies.
“ODOT has done road diets elsewhere in the state. For whatever reason, ODOT Region 1 isn’t on board.”
— Anthony Buczek, Metro travel engineer
“There’s just not enough detail in the model to assess accurately the travel times or the amount of diversion,” said Buczek. “We thought we had communicated that pretty clearly to ODOT, so I think we were a little surprised to see the data released as it was.”
Buczek said the “correct” numbers, if any, came from a subsequent study by Metro and the City of Portland, using Synchro SimTraffic software, that found additional auto travel delays of about 10 percent by 2035, mostly because a restriping would force all northbound cars to drive only as fast as the slowest car.
Afternoon rush-hour travel, meanwhile, might actually be accelerated by dedicated bike lanes, because they would prevent southbound cars from having to share a lane with bikes. No studies have yet looked into southbound traffic impacts.
This was around the same time that total auto miles traveled in Oregon began falling statewide, and five years before the latest recession.