Last January, early results from a Portland State University study of the boxes failed to conclusively show a significant reduction in conflicts between cars and bicycles at tricky intersections
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.
Officials plan to nearly double the number of $6,000 bike boxes around the city in the coming year.
Ironically, the first of the new boxes is planned for Northeast Couch Street at Grand Avenue, where a right-turning truck hit a woman riding a bicycle during Wednesday’s morning commute. The cyclist suffered a broken foot.
City officials modifications to the intersection has resulted in several reports of “right turn conflicts” in recent months.
“We’re increasingly seeing evidence that bike boxes are needed in more locations,” said Greg Raisman, a PBOT traffic safety specialist. “The latest results from this study are very promising.”
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 a small sample of video before and after boxes were installed at intersections.
After increasing the study’s sample size and revisiting some bike boxes, their effectiveness is “more clear,” Dill said.
The bike boxes are designed to reduce the chances of motorists making right turns into the path of bicyclists in bike lanes. In the fall of 2007, two Portland cyclists were killed in so-called “right hook” crashes in which they had the right of way.
Portland now has 14 intersections with the boxes. Most are painted green to get drivers' attention.
At red lights, only bicyclists can stop in the boxes. Cars and trucks must line up at a 24-inch "stop bar" behind the boxes. Also, motorists at the intersections no longer can turn right on red, even if bicyclists aren't in the boxes or green bike lanes leading to them.
Motorists at red lights who enter the boxes or turn right could face a $242 fine. Bicyclists are also subject to fines if they break the rules.
In the end, Dill, PSU transportation researcher Chris Monsere and their team coded 83 out of 918 hours of video, in which they kept track of usage and compliance among 5,315 cyclists. Additionally, they reviewed 139 hours for potential conflicts between motorists and 7,454 cyclists.
They also analyzed the “yielding behavior” 1,141 motorists during 17 hours of video, when 135 of the drivers found themselves in situations where they needed to yield.
The study (PDF) showed that 73 percent of motorists properly stopped just before the bike boxes. Also, 86 percent of the 721 motorists recruited for an online survey by PSU “indicated an understanding of the bike boxes” -- -- Dill said.
Bicyclists also appear to have a solid understanding of how the boxes work, with 73 percent in the videos using them properly. What’s more, the study found, the number of cyclists encroaching into crosswalks at red lights decreased significantly.
While the number of cyclists at the intersections increased 32 percent, conflicts between motorists and bike riders decreased by about 31 percent after boxes were installed.
“We’re still not sure about whether the green color makes a difference,” Dill said.
For the study, PBOT agreed not to put green textured thermoplastic on three of the city’s bike boxes.
Still, Dill said, the survey found the vast majority of motorists prefer bike boxes with the green textured thermoplastic.
Also, she said, some evidence suggests motorists and bicyclists were more inclined to follow the stopping rules at green boxes.
Raisman noted thatfound that bike boxes in Austin improved safety where the risk of right hooks is high. Bike advocates in Portland and other cities are urging the federal government to adopt bike boxes as a national safety feature on roads.
Portland traffic engineers have also announced plans for 11 intersections to received boxes. The city lays out its rationale for each in this spreadsheet:
- Northeast Couch Street at Grand Avenue (where, ironically, a bicyclist was hit by a vehicle turning right this morning).
- Southeast Madison at Grand.
- Two boxes Southeast 26th Avenue at Powell Boulevard.
- Southeast Seventh Avenue at Hawthorne Boulevard.
- Southeast Seventh Avenue at Madison.
- North Interstate Avenue at Tillamook Street.
- Southwest Terwilliger Boulevard at Capitol Highway.
- North Interstate Avenue at Alberta.
- Two bike boxes at Southeast Gladstone Street at Cesar Chavez Boulevard.
- North Willamette Boulevard at Portsmouth Avenue.
- Two bike boxes at Southeast Lincoln Street at 39th Avenue.