After two years, Portland's green bike boxes appear to be moving out of the experimental phase and into the city's permanent toolbox of traffic-safety features.
In January, early results from a Portland State University study of the boxes failed to conclusively show that the boxes actually cut the number of bike and car crashes at tricky intersections. A preliminary analysis of 918 hours of video shot at 12 boxes failed to show a significant reduction in conflicts between cars and bicycles.
Eight months later, however, researchers say they are now convinced that the green zones stretching from bike lanes to 14-foot-long boxes in front of crosswalks help save cyclists' lives.
And the Portland Bureau of Transportation is wasting no time planning more bike boxes at several intersections identified as having "right hook" risks for bicycle riders. They plan to nearly double the number of $6,000 bike boxes around the city in the coming year.
Jennifer Dill, co-author of the study and director of PSU's Center for Transportation Studies, said the information released at the beginning of the year was based on incomplete reviews, or "coding," of video before and after boxes were installed at intersections.
After increasing the study's sample size and revisiting some bike boxes, the effectiveness of the boxes is now "more clear," Dill said.