Portland's experimental green bike boxes, which began popping up around the city in 2008, have somehow made a handful of tricky intersections even more dangerous.
At least that's what the crash numbers seem to suggest.
"The crash data trend suggests that right-hook crashes are increasing at some of the treatment locations installed in the first phase," said city traffic engineer Rob Burchfield in a signed "progress report" to federal highway officials that was released late Monday (PDF).
During a four-year period, the number of crashes involving a motor vehicle turning right into bicycle riders, so-called "right hooks," doubled from 16 to 32, Burchfield writes.
Burchfield said most of the right-hook crashes occurred at four intersections, including Southwest Madison Street and Third Avenue, where Kathryn Rickson was killed in a crash involving a right-turning semi freight truck.
The letter also lists Southeast Hawthorne Boulevard's intersections with Seventh and 11th avenues and Northwest Everett Street at 16th Avenue.
The letter appears to be in response to questions from Mark Kehrli, director of transportation operations at the Federal Highway Administration, regarding Rickson's death.
Burchfield said the crashes involved people on bicycles who were going downhill and picking up speed. "The speed of cyclists overtaking right-turning vehicles is likely a contributing factor that may explain the safety performance" of the locations, he said.
At the same time, Burchfield said studies show about 98 percent of vehicles properly yield to bicyclists at the boxes. He is also confident that the boxes are also ultimately preventing conflicts as the volume of bicycle commuters passing through the boxes increase.
The Portland Bureau of Transportation, he writes, is developing plans for possible modifications at the four bike boxes with crash problems. They run the gamut, from including separate right-turn lanes and just prohibiting vehicles from turning right.
Burchfield said Portland State University is in the process of conducting an ongoing study of how the bike boxes are working out.