TheWashCycle

What can the bike-sharing helmet study tell us?

A couple of weeks ago the American Journal of Public Health published a paper by Janessa Graves of the Harborview Injury Prevention & Research Centerthat asserted that public bike sharing programs (PBSP), like Capital Bikeshare, were "associated with increased risk of bicycle related head injuries." Primarily this claim was based upon an analysis of "trauma center data for bicycle-related injuries from 5 cities with PBSPs and 5 comparison cities." This analysis showed that in PBSP cities, head injuries increased from 42.3% to 50.1% after implementation, while in non PBSP cities the ratio remained basically the same, 38.2% before implementation in those cities and 35.8% after. The study has several potential problems with it's methodologies, conclusions and how it was reported in the media. But mostly I want to focus on what we can get from this study and how we can move forward. 

The biggest problem I have with the study is the way that it buried the lede. The most interesting thing about it was not that, in PBSP cities, head injuries increased as a percentage of all injuries; but that in cities that launched PBSP, traumatic bicycle-related injuries (including head injuries) decreased more than in cities that didn't. And as a result, many news organizations mis-reported the conclusions, NPR entitled their article "Head Injury Risk Rose In Cities After Bike-Sharing Rolled Out", when in fact it went down. The Post's Lenny Bernstein had to change his title after criticicm of it, but the article still says that claims that "bike share programs are very safe, much safer than, say, crusing around on your own bicycle" are wrong, when, in fact, the conclusion one would make based on this study is that those claims are correct. 

The study has many limitations that bring even its central result into question. When I talked to Graves about the study and some of its limitations she leaned heavily on prior studies showing helmet efficacy and seemed to imply that this was no longer in question. In the paper, she cites the controversial results of Thompson's studies that continue to show much higher efficacy than other studies. Of course if the thesis is that Thompson has showed helmets to be very effective, and we need to do more to make them available to bike-share riders, then why do we need this study? The conclusion has to be able to stand on its own.

But the real shame is that the results, even if true, do not sufficiently support the paper's conclusion that "steps should be taken to make helmets available with PBSPs. Helmet availability should be incorporated into PBSP planning and funding, not considered an afterthought following implementation...Promotion of helmet use through integrated rental programs should be a critical element of all PBSPs. This would provide users with the opportunity to reap the benefits of the PBSP while contributing to their safety."

The idea that - all other things being equal - if cyclists wore helmets more often, there would be fewer head injuries is not particularly crazy. If people wore helmets more often in general there would likely be fewer head injuries. But you can't get to the conclusion that bikeshare should do more to promote helmet use through integrated rental programs until there is data that shows that integrated rental programs reduce head injuries - and that they do so without causing more injuries elsewhere, or reducing bike-share use and its many health benefits. Instead, she cites a news story that Citibike is offering limited helmet rentals in New York City. 

The best conclusion one can make from this study is that bike-sharing makes biking safer, but the low-rate of helmet use might represent an opportunity to build on those gains if an effective way of encouraging more helmet use can be found. But mostly this study's results leaves me with the sense that more research is needed. Here are some examples of what could be done next:

• If the Citibike helmet rental program is a model to be followed, has it increased helmet usage? Has the increase in helmet usage reduced the head injury ratio without increasing total injuries? How did ridership change? Are there other programs that are working?
• Is the injury ratio result valid?
• Using only 1 year's post-PBSP data means that we only have 1 winter's worth of data, if that winter was more harsh than the prior two, perhaps that caused more head injury crashes. 
• The study compares 5 cities to 5 others. But one of the controls - NYC - made up 60% of the population in the control cities. And while in each group there was one sunbelt city, in the PBSP group it is Miami Beach, which made up only 2% of the PBSP population, but in the control was LA which made up 27% of that population. More data from more cities would help.
• 2 of the 5 control cities have mandatory adult helmet laws, but none of the PBSP cities do.
• The pre and post implementation dates aren't exactly right, as in DC, for example, post-implementation starts on May 1, 2010, but the program didn't start until 5 months later. The study should be reworked to tease out the correct time period. 
• We need better data on the head injuries themselves. Did skull fractures go up in PBSP cities, because that's the kind of head injuries we'd expect to see a helmet prevent. If instead there were more broken jaws or concussions, then it might be something else that is causing this?
• What happened to other kinds of injuries. For example, what if broken collar bones plummet in PBSP cities? Perhaps the change in injury ratios is the result of slower riding. Or fewer rear-end collisions because the bikes all have lights. Or perhaps it is in part caused by an decrease in neck injuries in PBSP cities since some studies indicate helmets can cause more neck injuries. More data on other injuries broken out by group would help to eliminate the possibility that PBSPs are just better at reducing other injuries than they are at reducing head injuries.
• How does the population of PBSP users differ from other cyclists and can any differences be controlled for?
• How does the population of PBSP trips differ from other bicycle trips and can any differences be controlled for?
• What percentage of total miles biked in each city is by shared bike, and is that enough to account for the difference in ratios?

These are not meant to be criticisms. This wasn't a study of the things I listed. Science is an incremental, collaborative and iterative endeavor, and the Graves paper wasn't meant to be a comprehensive study. When I talked to her she was clear that she saw this as a starting point, and I think as such, it's valuable. I disagree with the conclusions, and I'm not 100% confident that the results will stand up, but I want to see more.

If it turns out that there is a cost-effective way to get more bikeshare riders to wear helmets, that would be a good thing, because as Graves pointed out in our conversation, there are likely people who are choosing not to use bikeshare because they won't ride without a helmet and can't get one at the time they want one. If it turns out that a method for making rental helmets available improves public health, all the better. If we can improve public health and still reap all of the land use, mobility, pollution reduction and congestion relief of bike share, who would possibly oppose that? Not me. 

LAB studies cyclist fatalities and turns up some fascinating data

The League of American Bicyclists recently released a report on bicyclist fatalities and some of the results are pretty interesting, in that they greatly differ from the results of other (sometimes questionable studies). 

Between February 2011 to February 2013, the organization sifted through hundreds of cases from across the country. Using newspaper and television reports and blogs, they were able to get a closer look at 628 individual cases and tease out some patterns.

That's pretty close to half the fatalites over that period, considering that lately the average number has been a little under 700 per year. 

1. In 40 percent of the cases, the victim was struck from behind. 

In most cases that I've seen, when a cyclist is hit from behind, the driver is at fault. Sometimes the cyclist is riding at night, in ninja-mode, but that is not the usual. So, by far the biggest group is one where driver's are at fault in most cases. Another 6% are driver failed to yield, compared to 2% for cyclist failed to yield and so cyclists would really need to be overrepresented in every other category for it not to turn out that drivers are more often at fault. This is something the report doesn't try to determine, but it certainly raises eyebrows.

In addition, there were 236 fatal crashes where a factor was reported for the driver. In 86 cases (36%) the driver was reported to have committed hit and run, which doesn't mean they were at fault for the crash, but it's still a pretty heinous crime. There were also 28 (12%) reports of driving under the influence (which may overlap with some of the other groups listed above) and 101 (42%) where they were reported to have been operating their vehicle in a careless or inattentive manner.

For cyclists, the most common factors reported, out of 94, were wrong way cycling (22%), failure to yield (17%) and riding on the sidewalk (9%). For the last, it would be helpful to know how what percentage of bike miles are on the sidewalk (especially since children are over-represented in both fatalities and sidewalk cycling). 

2. In the 150 cases where helmet use was cited in a crash account, 57 percent of the victims were wearing a helmet.

This is WAY below the usually cited numbers from FARS data that is often reported in the media (and the report notes this as well), such as in this recent Post article

Between 1994 and 2010, at least 70 percent of the cyclists killed in the U.S. each year weren’t wearing helmets, and in many of those years, the proportion was more than 90 percent, according to the Insurance Institute for Highway Safety.

Considering that studies place helmet use rates at around 50%, a helmet use rate of 57% for cycling fatalities would undermine the claim that helmets save lives (even if that is true, and more data is obviously needed, helmets might still reduce injuries or even pain). Regardless, it does bring the FARS data further into question. 

This is not particularly surprising: 

Working from press accounts to compile data on bike crashes can be tricky, because as the League notes, stories tend to be told from the survivor’s perspective. Basic facts like who had the right of way are often overlooked, and crashes are often presented in a manner that exculpates the motorist.

Bad science and helmets

The Post has a couple of helmet articles today, one about why you should wear a helmet and the other about why bikeshare doesn't provide them.

The first article argues that since an overwhelming majority of cyclist deaths between 1994 and 2010 involved cyclists who were not helmets, that is all you need to know to know that you should always wear a helmet. There is a case to be made for wearing a helmet (I usually do and I think you're probably better off doing so), but this isn't it. Rather than write a reply, I'll just point you to Crikey's excellent comment:

While I do recommend wearing helmets, this pie chart proves nothing. The pertinent fact would be the percent who wear helmets and their relative survival rate, not the overall relative survival rate. What's more, a more rigorous look at the actual research shows a statistically significant but fairly modest, and overall somewhat unclear, impact on head injuries. Finally, helmet design is done in accordance with federal standards that have not kept up with the findings of more recent studies. It's possible that helmets could be much better, but there is no incentive, and some disincentive, to making them so.

And to that I'll add that the data that the pie chart is based on is dubious at best. 

this data is based on Police Accident Reports and many of these do not include a separate entry for bike helmet use. So the FARS data is based on the crash narrative. If no information is given, it should be listed as unknown.

Unfortunately, it appears that nearly all of these cases that should have been coded as "unknown" (including a considerable number where the bicyclist actually was using a helmet, but such usage was either never noted or overlooked in the narrative) were instead coded as "not used"

One strong indicator that the FARS bicycle helmet use data should not be fully trusted is the fact that the "unknowns" are so few in number. It is simply not credible that a low priority data element such as bicycle helmet use would have a precision associated with it that is a factor of 20 better than that seen for much higher priority data elements such as seat belt or motorcycle helmet use (0.5% "unknowns" vs. 11% or 10%)

The second article, by child-of-rabid-R.E.M.-fans Leonard Bernstein, is a pretty alarmist article about not wearing helmets on Capital Bikeshare. He relies largely on the stat debunked above and the somewhat discredited, but widely repeated 1989 study. You can read about the criticism of that study here. Even the NHTSA has admitted that the study isn't robust enough to meet the standards of the Data Quality Act. 

Though he starts with the claim that the stats on bicycle helmets are abundantly clear, he undermines his whole case that bikeshare riders need helmets later on.

In four years, there have been no reports of a major injury to a Nice Ride Minnesota cyclist, Dossett said, and no head injuries at all. Much the same is true for Washington’s Capital Bikeshare program, which has had fewer than 100 reported crashes since 2010, despite 6.8 million bike trips, said Kim Lucas, the program manager.

And his claim that "Seattle and Boston have found ways around" the problems related to providing bikeshare users with helmets is not accurate. They have programs they are going to try. They have not shown that they will solve the problem, or that the helmet vending business is worth the expense.

Holly Houser, executive director of Pronto Cycle Share in Seattle, said the helmet vending machines added about $850,000 to the $4.4 million that will be spent on bicycles, docking stations and other equipment.

“It would be much easier if we did not have the mandatory helmet law,” she said. “We all know that.”

Seattle's bike share system will be the first in the US to go into place in a city with a mandatory helmet law. We'll see how much that impacts ridership. 

The answer to the question raised by the second article "Why don't bikeshare programs provide helmets?" is pretty clearly that, since injuries are so rare, it isn't worth the price. 

A woman riding without a helmet?

A writer to the Post was upset that the Post showed a photo of Lia Seremetis without a helmet riding a bike in DC

This is at least the third time that The Post has pictured a cyclist without a helmet, seemingly condoning this unsafe practice. After at least one of those occasions, a disapproving letter was printed. Yet here it has happened again.

While the article was not about bicycle safety per se, it was still disappointing to see such an image. It was especially disconcerting that the young woman pictured is the organizer, according to the article, of “a monthly city ride . . . that draws hundreds of enthusiasts.”

Let’s get the message straight and send it loud and clear: It is unsafe to ride a bike without a helmet.

Sigh. Just because the Post shows a photo of an activity doesn't mean they condone it [They've also published photos of child soldiers for example]. The letter writer was astounded to see such a photo - and is sure that other cycling enthusiasts are too - despite the fact that many cyclists choose to ride this way and the Post has published them before. Is the Post not allowed to show the world as it actually is? Are they now required to make value judgements about how it should be and only show images that meet with that view? Should they not show photos of protesters arguing because that isn't how they think people should behave? The letter writer should just accept that the Post is not going to force Ms. Serementis to put a helmet on before they photograph her anymore than they will force her to put sunscreen on. 

As to whether cycling is unsafe without a helmet...I'll go with cycling is likely more safe with a helmet than without, but not sure that the helmet is the difference between safe and unsafe. 

Lawyers argue that bikesharing could have a lawsuit on it's hand

Because a Chicago bike rental company was sued after they violated their own unwritten policy of giving riders helmets and safe riding instructions to a cyclist who was subsequently injured in a dooring, some Chicago lawyers think that Divvy is a legal reciped for disaster. [The rental company settled, which is too bad because I'd love to see a lawyer try and prove that a helmet would have helped the cyclist in the dooring].

Jeff Kroll, a partner at Salvi, Schostok & Pritchard who negotiated the settlement for Cohen, sees similarities between the case he brought against Lakeshore Bike and Divvy’s policies. “I don’t think they’re dissimilar in the sense that you’ve got companies in the business of making money, but they’re not taking the extra steps to make sure people are safe,” Kroll says. “I think this is going to be Pandora’s box. With more pedestrians being hurt, more dooring accidents, the question will become, what responsibility does Divvy have?”

I think these two cases are very different, and that the bike rental company should not have settled, but I'm not sure what they think Divvy could do short of having someone stand by kiosks and make sure cyclists wear helmets.

 “Harm is totally foreseeable,” says Christine Hurt, professor at the University of Illinois College of Law. “A kiosk in downtown Chicago that doesn’t provide bike helmets? I think that’d be a pretty good fight.”

Says someone who has no idea what the efficacy of helmets is or how rare it is that bikeshare users are injured or that city cycling is actually safer than suburban cycling.

And I suspect the average Divvy rider is not "clueless".

 

Sunday Video: Let your helmet be your guide

Wednesday Afternoon Commute - Everything is safer than cycling

Good afternoon

• The DC Council considered the Bicycle Safety Amendment Act of 2013 today.
• The push is on to further limit sidewalk cycling. “We understand that there are concerns with sidewalk bicycling, but we think that sidewalk riding is normally a problem where there is not a space in the roadway that bicyclists perceive as safe,” said Shane Farthing, executive director of the Washington Area Bicyclist Association. Jeanne Mallett is really worked up about sidewalk cycling. 
• Crowd-sourced bicycle maps of cities, including DC. 
• ANC 3D should support bike lanes on New Mexico Avenue. 
• DC Bike Party organizer's bike stolen before 1 year anniversary ride (this Friday).
• Long Bridge Drive, which will feature bike lanes that might some day connect Arlington to the MVT, might finally be ready for construction. 
• Centerville Football coach is either wrong, or misquoted "Haddock said the highest rate of concussions in youth sports occurs in girls soccer, and the highest rate of concussions in the United States stems from bike accidents." He's talking about NUMBERS, not rates and not at the high school level. Either way, it's deceptive to try and cast football as less of a concussion risk than cycling. The numbers are higher because far more people participate in those sports. Concussion rates for football are the highest in all high school sports. I'm unaware of any data on concussion rates for cycling, but I'd be stunned if they're higher for cycling than for football.  While there are twice as many bike-related concussions per year than in football, there are far fewer people playing football than biking (for starters, almost no women play). 
• Speaking of failing to consider the denominator. Here's someone arguing that Mixed Martial Arts fighting is safer than cycling because more people die while cycling. He also fails to consider the benefits of cycling - everything looks bad when you only consider the costs [Thousands of people contract sexually transmitted diseases each year? Well, I guess it's cold showers for me from now on.] "Is it all so simple that we can just ignore the hard numbers behind these two activities and two data sets?" he asks. Apparantly, it is.  By his logic it's safer to play Russian roulette than bike, because fewer people die doing it. [I don't have an opinion on MMA and whether it should be legal or not, but casting Citibike as dangerous or biking as more dangerous than fighting without using all relevant data is bad form]. 
• Friends of the Capital Crescent Trail are back to pushing the idea that light rail near high schools is dangerous - because two men who were too old to be in high school were hit by a different kind of train at a time of day when high school students would not be at school. But there is no reason to fear roads near schools. None at all.
• "The Montgomery County Planning Board approved the facility plan for the North Branch Hiker-Biker Trail on June 27"
  • The south end of the proposed trail will connect to the existing Lakeside Trail located on the east side of Lake Frank within Rock Creek Regional Park and will continue north to connect with Muncaster Mill Road and cross at the Emory Lane intersection. The trail then will use the Emory Lane Bikeway and cross the Intercounty Connector Bikeway to the ICC bridge over the North Branch of Rock Creek. The proposed trail will go under the ICC bridge and connect to a future hard surface trail, which will be constructed by the developer of the Preserve at Rock Creek and will be dedicated along with parkland to the Department of Parks. The developer-built trail will end at Bowie Mill Local Park.
  • There was a suggestion to connect the trail to two local, dead-end roads, but residents of those roads didn't want the trail connections. “Connecting the trail is important to the Olney community, as it is a missing piece of a larger network, said association President Barbara Falcigno. “GOCA feels the master plan alignment that keeps the trail within the natural area is preferred over directing users onto roads.”
  • "The resolution also stated that GOCA feels the trail route should stay off area roads such as these which do not have a shoulder or sidewalk, which could make it unsafe for users."
• "The 2013 Giro di Coppi bicycle race will take place in the Sugarloaf Mountain region beginning at 9 a.m. Saturday"
• At least he wasn't on the sidewalk. 

Monday Afternoon Commute - Karaoke

Good afternoon

• The DC BACs bi-monthly meeting is this Wednesday.
• DC Bike Party celebrates it's 1 year anniversary with a bike birthday party.
• Also, bike karaoke.
• "Local commissioners from ANC 3D will vote on the New Mexico Avenue NW bike lane at this month's meeting on Wed., July 10th. Your attendance and voice of support is needed!"
• Maryland Governor Martin O'Malley promotes transportation projects in Prince George's County including "$46 million for several bicycle, pedestrian and safety improvements along various roads in Prince George’s, including U.S Route 1 in College Park." Of that, $20 million will be used buy right-of-way for a bicycle and pedestrian trail along U.S. 1 from College Avenue to Md. 193 in College Park.
• The Alexandria Bicycle and Pedestrian Advisory Committee is still looking for volunteers for documentation project counts Thursday July 11th (5-7pm) and SaturdayJuly 13th (12-2pm).  Go to their webpage for additional information:  www.bicycle.alexandria.va.us/  
• Takoma Metro development plan will include a bicycle station with parking for 105 bikes. I don't know if the Met Branch Trail design has been finalized yet, but one of the preferred alternatives called for a sidepath through this area. 
• Surprise! Bike share in NYC is a big success. Though ABC got a little confused on the facts in DC. "Washington D.C. began its program in 2008 with 120 bikes and 10 stations. It has expanded to 1,800 bikes and more than 200 stations." And despite trippling bike parking in Boston, it can't keep up with demand. 
• Bike helmet made from recycled newspaper.

AP takes John Pucher quote way out of context - and then builds story around it

According to an AP story

The lack of a helmet requirement in New York’s month-old Citi Bike program...has some experts predicting a disastrous increase in injuries and fatalities. 

But, 

so far, through more than 500,000 rides, such predictions haven’t come true, with just three minor accidents and nothing more serious than some scrapes and bruises.

John Pucher is the only expert they cite [unless you count comedian (and former roommate of my former boss) Jon Stewart or the AAA-New York spokesman as experts], and while I certainly think he's a knowledgeable guy, they don't actually have a quote from him and they lump helmets in with other possible causes.

A lack of a helmet requirement, blocked bike lanes and inexperienced cyclists hitting the road are all reasons Rutgers University public policy professor John Pucher cited in predicting that the number of cyclist injuries and fatalities will double or even triple in Citi Bike’s first year.

And near the bottom of the article they have a study that seems to contradict this.

The Mineta Transportation Institute in California studied 14 bike-share programs and found relatively low accident rates, averaging 1.36 serious or fatal accidents in 2011. In the same year, there were 22 fatalities for bicyclists in New York.

The fact that DC and Boston have been relatively safe isn't even really mentioned. They do pull out the discredited claim that 

in 97 percent of bike fatalities from 1996 to 2005, the rider wasn’t wearing a helmet.

The statistic itself is somewhat daming in isolation, but no more so than pointing out that 100% of bike fatalities in the same period were not wearing rainbow colored suspenders. They don't give a citation, but it is likely this report which also notes that only about 13% of New York cyclist were even wearing helmets during that time. Add in the fact that often the helmet use was unknown and that the reporting of helmet use in fatalties is frequently reported wrong and this statistic is just above junk status. That's not to say that helmets aren't useful, only that this statistic makes them look more useful than they probably are.

The Pucher reference most likely comes from this article, but they wildly misread it. Pucher does mention that having more cyclists on the road increases total risk - just as the number of Segway related deaths has gone way up since the 1980's when there were none. But he does not in any way attribute that to helmets

"The problem with requiring helmets with bikesharing systems is they're generally meant to be for very short trips," says Pucher. "Let's say you get off the subway or Metro, and you just need [a bike] to cover maybe, say, ten blocks. It's unlikely you're going to carry with you a helmet to use for that ten-block ride."

Alternatively, he says, bikesharing programs would have to take on the difficult task of figuring out how to dispense one-size-fits-all helmets at every station.

Short trips also generally make for less risk than longer trips. And while they may not do so for safety purposes, bikeshare systems encourage shorter trips within their pricing systems. Capital Bikeshare, for example, ramps up the price after 30 minutes of riding.

While there is an argument that helmet laws are unnecessary, Pucher points out that more riders on the roads, particularly when new bikeshare systems open for business (like New York's Citi Bike, which launches in July), naturally leads to greater risk.

Then the money line - which isn't even really a prediction, it's a fear.

"All of a sudden, you've got these 7,000 bikes, which anyone with a credit card can use. ... My guess is the people using those bikes are far less likely to be experienced cyclists," he says of New York's new system. "What I fear is you're going to have indeed a spiking--and it could be a doubling or a tripling--of injuries and fatalities, both of cyclists and pedestrians."

So he's talking about inexperience cyclists - not helmets. He's also talking about pedestrian injuries spiking.

I'd love to hear what he thinks of the AP story.

Thursday Afternoon Commute - Guardian Angel

Good afternoon

• More MBT attack follow-up here. WABA's planning a safety walk. And those cameras DC installed? Almost entire for show.  It's clear we're going to need an Enforcement Droid* 209. 
• The complete history of road lanes and how cyclists got kicked out of them. Long, but good. "The UVC therefore gave bicyclists the superficial appearance of being drivers, but without the right to use travel lanes like drivers. Although a travel lane is intended for a single line of vehicles, bicyclists were told that they could not use travel lanes like real drivers. Bicyclists were told they had to ride at the right edge and if they strayed from the edge, they were doing so at their own peril. Bicyclists were now officially second-class road users."
• "Crashing without a helmet exposes the head to accelerations and forces – or loads - up to 9.5 times greater than with a helmet and so greatly increases the risk of head, skull and brain injury, according to a detailed biomechanical study published in the journal Traffic Injury Prevention."
• Because only rich people live and work in Manhattan and Brooklyn and only poor people live in the other bouroughs, bikeshare is part of the dividing of people into haves and have nots leading to a dystopic future from out of a sci-fi novel. Or something. 
• Is it possible to create a cycling superhighway parallel to Route 50?
• Dockblocking makes people sad.

*Since George Lucas owns the word "Droid" I guess he makes money off the Robocop franchise?