Imagine cars stopped at a light. Bike boxes are an area ahead of the stopped cars. A bicyclist approach the line of the stopped cars is supposed to go to the front of the line, to turn left, right or go straight. One of the benefits is to make a left turn easier. The problem with that though is that as the slowest vehicle in the que, cars behind the bicyclist turning left might not get through the intersection before the light turns.
Bike boxes also supposed to fix the problem of right hooks, in which a car not seeing a bicyclist approaching cuts the bicyclist off. By putting the bicyclist at the front of the line, he or she can execute the right hand turn without being cut off.
While the photos on the City of Indianapolis' bike box web page shows those boxes being used in conjunction with bike lanes, they don't have to be. The blog Urban Indy, which supports anything the City does regarding bicycling, no matter how poorly thought out, notes that Indianapolis has installed a bike box at the intersection of Spring Mill Road and 73rd Street where there is no bike lane.
In October of 2012, the Portland's Traffic Engineer issued a report to the federal government that the number of vehicle-bicycle right turn crashes had actually doubled since the bike boxes were put in. The Portland Mercury reports on that report:
In the four years leading up the installation of the bike boxes, there were 16 right hook crashes at the problem intersections involving bikes. In the four years since their installation, the intersections had 32 right hook crashes involving bikes.
What appears to be leading to the new crashes in that people are biking through the intersection faster, overtaking cars that are turning right. While the bike boxes have been good at stopping right hooks when both the car and bike are starting up from being stopped at a light, 88 percent of the crashes happened at a "stale" green—not from a dead-stop but from a turning car striking a cyclist who's in motion, pedaling down the block and through a green-lit intersection. That's the kind of crash that killed Rickson this spring.One of the Portland right hand accident involved a fatality as a female bicyclist began passing a truck on the right hand side at a "stale green" light. The truck ran over the bicyclist and pinned her under the wheels at the back of the cab.
It's not clear exactly why the new type of crashes are occurring—it could be that the bike box's documented effect of increasing the "perception of safety" actually leads to people biking or driving less hesitantly through the intersection because they think they're in the clear.
A Portland bicyclist wrote about problems with the bike boxes on his blog. He also provided the below video showing him getting cut off, which he said happened three times in a week.
(Note: That Portland bike lane is incredibly dangerous in another way. It is very narrow and runs right next to parked cars. At any minute, a driver of one of those parked cars could open a door causing the the bicyclist to hit the car or swerve into traffic. That is called "dooring" and is probably the most dangerous thing that an urban bicycle commuter can encounter. You NEVER ride a bike right next to parked cars.)
Portland traffic engineer proposed changes to the bike box intersections to fix the dangerous bike box intersections. The proposals did not include eliminating the bike boxes. Rather those proposals included a redesign of the intersection by removing a through traffic lane or removing parking, prohibiting vehicle right turns, providing a separate traffic signal for the bicyclist, or provide traffic warning lights that are triggered by approaching bicyclists. All the proposed fixes involve much more cost to the taxpayer and decreased convenience for the motoring public.
It should not be surprising that motorists have trouble seeing bicyclists, especially when the bicyclist is cutting through the driver's blind spot.. when a bicyclist is passing a slowed or stopped car at a light, it is quite possible that the motorist will never see the bicyclist as he or she turns the vehicle. That's why bicyclists need to always be on guard, always vigilant, always proceeding with the assumption that the driver of the auto cannot see the bicyclist. Too many times bike lanes and bike boxes have bicyclists doing things contrary to what is standard bicycling safety practices. Perhaps worse is that bike lanes and bike boxes often cause bicyclists fall into the false sense of security that a line on the pavement will protect them from a collision with a several thousand pound vehicle.
Once again, the City of Indianapolis saw something, in this case bike boxes, that had failed in another city, and proceeded to adopt it anyway. Make no mistake about it. Bike boxes are not about safety. They are about city officials pandering to members of the Indianapolis recreational bicycling community who are so thrilled that someone is finally paying attention to them.