It’s no surprise Cambridge roads are getting safer
This Spring, the Federal Highway Administration published a summary of a study looking at data from Cambridge and four other cities. The conclusion: Separated bicycle lanes resulted in approximately 50 percent reduction in bicycle crashes compared with traditional paint-only bike lanes. Already in 2015, the Massachusetts Department of Transportations’ Separated Bike Lane Planning & Design Guide summarized the then-available body of research evidence on these lanes (Chapter 1, Page 4), noting that:
- “Separated bike lanes attract more people to bicycling.”
- “Women express a preference for separated bike lanes.”
- “Separated bike lanes improve safety for all road users.”
Based on this and other research, and significant community engagement, the City’s 2015 Bicycle Plan called for a complete network of separated bicycle lanes; significant installation started in 2017. In 2019 and 2020, the City Council accelerated the installation of the lanes with the passage of the Cycling Safety Ordinance.
And yet, while city, state and federal experts consider separated bicycle lanes to be a proven safety technique, some opponents claim they are dangerous and increase traffic injuries. In a recent opinion piece published by a group trying to sue Cambridge to remove bike lanes, they suggest the safest infrastructure is no infrastructure: Cyclists should ride in the street with motor vehicles and behave the same way as motor vehicles. Contrary to the city’s focus on infrastructure that protects against mistakes and works for a wide range of abilities, they suggest “cyclists … and pedestrians must learn to assume responsibility for their own safety.”
We evaluated these competing theories of street design by comparing outcomes in Cambridge to outcomes in locations following the no-safety-infrastructure approach. Cambridge is certainly an outlier – we would say a leader – in the extent of its separated bike lane installation and other safety infrastructure. The rest of Massachusetts is much closer to bike lane opponents’ preferred street designs, for the most part either lacking separated bicycle lanes or at best lagging far behind.
To compare the two approaches, we chose two metrics (for more details on why, and the raw numbers, see the full report):
- For Cambridge: Crashes in Cambridge that resulted in EMS transport to the hospital, a good proxy for the severe injuries that the city’s Vision Zero policy seeks to eliminate, and used by the Cambridge Police Department in its annual report. This includes crashes for all modes of transit (motorists, pedestrians and cyclists), as long as someone was taken to a hospital.
- For Massachusetts (excluding Cambridge): Traffic fatalities in the rest of the state for all modes of transit; and for pedestrians and cyclists only.
Cambridge began major installation of its lanes in 2017, so we compared each metric’s change over time from the 2016 baseline level. By 2022, Cambridge had installed 11 additional miles of separated bike lanes on high-volume or high-crash streets, plus numerous other investments in street design safety improvements.
Here’s what the resulting outcomes look like:
The figure above shows a stark reduction from 2016 levels in crashes resulting in emergency medical transports in Cambridge (the blue line in the top graph) as the lanes were installed in Cambridge. Conversely, in the rest of Massachusetts, traffic fatalities and fatalities involving pedestrians or cyclists have increased compared with pre-pandemic levels (red and orange lines). Note that 2020 is anomalously low, presumably due to the pandemic.
The Cambridge Police annual report from 2021 reaches a similar conclusion, looking at a different data measure: “In 2021, there were 1,172 crashes reported … down 21 percent when compared to the 10-year average of 1,479 crash reports.” The Cambridge post-crash hospital transport data for 2022 is still preliminary and will likely be revised slightly upward, but the message is similar: Cambridge is much safer compared with 2016, even as Massachusetts traffic fatalities rise.
The city’s transportation department is a leader in traffic safety, relying on proven safety techniques endorsed by state and federal experts; this includes separated bicycle lanes, but also reduced speeds, leading pedestrian intervals and much more. To achieve the goal of zero fatalities and severe injuries from traffic crashes, we must continue implementing safer infrastructure based on the city’s proven expertise.
This letter is not signed, and written by “Cambridge Bicycle Safety”. Is this an organized group? Person?
It’s an organized group active in the city for several years. It’s at https://www.cambridgebikesafety.org.
Marc — Thanks for the link. I do, however, think that signature by an actual human should be required for opinion letters. Something like “By J. Smith, President, on behalf of Name of Organization.”
For what it’s worth, the group offered a lead author in Itamar Turner-Trauring, but I realized that identifying group authorship is not new, and had been done for groups such as the Cambridge Citizens Coalition and Cambridge Plant & Garden Club as well.
seems these oped LTEs should be signed. I signed mine. Doing so exposes each of us to potential vitriol from opponents but that’s the price of free speech – I think at least a leader’s name would be provided.
@BarbaraAnthony, it is written by Itamar Turner-Trauring on behalf of Cambridge Bike Safety, as Marc Levy said.
When the only thing people are commenting on is meta issues like group authorship, you know the substance of the post is spot on.
One reason that authorship of this piece was addressed is that groups of bicycle advocacy partisans have gone out of their way to attack (sometimes viciously) anyone who has a different viewpoint – here, on NextDoor, or on various neighborhood listserves.
There is one recent Cambridge-specific study that reveals that accidents are actually up here; however those results need to be reconfirmed.
Interestingly other studies suggest the same thing, due in part to the types of separated bike lanes being built in Cambridge and the great number of intersections (crossings) that bikes, cars, and pedestrians must cross in a dense city such as ours (which greatly increase the odds of accidents).
One learns for example that “In 2019, the Institute for Highway Safety (IIHS) reported on two studies focusing on the effectiveness of protected bike lanes, compared to conventional bike lanes. At the University of Colorado Denver and University of New Mexico, researchers confirmed that protected bike lanes are an important safety tool. They reported that cities with more protected bike lanes per square mile have fewer fatalities and serious injuries. But after studying cyclists in Washington D.C., the researchers advised cities to locate protected bike lanes on roads with fewer junctions or to use raised cycle crossings. Separately, the IIHS collaborated with researchers from three universities to study the characteristics of locations where cyclists were injured. Researchers studied 604 adult cyclists who crashed or fell on their bikes, then visited the ER in Washington D.C., New York or Oregon.
Compared to a major road with no bike infrastructure, the study found the risk for a bike crash or fall was much lower on two-way protected bike lanes running along bridges or raised roadway. But, two-way protected bike lanes on street level had a much greater risk for bike crashes. Researchers concluded that cyclists traveling on a protected lane at street level are still likely to encounter vehicles at intersections, driveways and alleys.”
https://www.iihs.org/news/detail/some-protected-bike-lanes-leave-cyclists-vulnerable-to-injury
https://www.bwglaw.com/bicycle-lane-accidents/
And we also know from NYC and elsewhere that more pedestrians are getting injured by bicyclists than before: https://nypost.com/2019/08/31/nyc-bicyclists-are-killing-pedestrians-and-the-city-wont-stop-it/
Here in Cambridge, the very low regular daily bicycle ridership levels ( c.7-8% of city residents or less?) the added traffic congestion, the added time needed to get where one needs to go in the city (which still has no viable transportation system), ongoing concerns about drop-offs and access for people with disabilities, issues around lost business clients, concerns about the huge financial costs and the lack of city transparency on the total costs now and going forward are other factors that have also raised concern. In short, we need far more study (by an independent non-city-affiliated group), a far more wholistic transportation plan, and far less grand-standing by bicycling advocates. Time will tell if the number of cars owned and used by city residents (seniors, those with families, or those who need to get to jobs) will significantly fall with the addition of bike lanes. This plus zero pedestrian and bicycling deaths is a key Envision goal. With climate change on us, adding more green space and trees along our streets and highways should be part of our overall plan along with ample set backs for new buildings so that trees will have ample place to grow. On this key issue see: https://studyfinds.org/new-york-city-hidden-greenery/
Nice to see actual data on the topic rather than a bunch of opinions and anecdotes.
Of course, bike lanes reduce accidents and increase. It is common sense. But, as always, it is great to see actual evidence.
Bike lanes save lives. We need more of them.
Cherry picked data. The total number of accidents rose but the data and article only counts the small fraction that required transport to hospital.
It is no surprise that just saying so does not make Cambridge Streets safer.
@Willard, this analysis directly refutes the thesis of the letter from John Hanratty with data from two independent analyses. Hanratty claims that protected bike lanes are making our city more dangerous for vehicles and cyclists.
That thesis is not supported by objective analysis of the police department’s severe injury/death data presented above (this just makes a graph from the data in the police department’s annual report).
The thesis is also not supported by the professional and independent analysis by the Federal Highway Administration, using data from four cities, including Cambridge.
Those are both independent analyses completed by third parties, one using data exclusively in Cambridge, and one by highway transportation professionals using data with Cambridge. What would you find more convincing and how could it be more independent?
@NC Walker The Cambridge Police Department is very clear that the number of crashes is down. A quote from the 2021 annual report (2022 is not available yet): “In 2021, there were 1,172 crashes reported … down 21 percent when compared to the 10-year average of 1,479 crash reports.”
https://www.cambridgema.gov/-/media/Files/policedepartment/AnnualCrimeReports/2021AnnualCrimeReport_FINAL.pdf
The difference in the 2 reports highlights that the CITY needs to weigh in. One big difference is the Hanratty report focuses in on 3 distinct locations where separated bike lanes have been installed and in those sections with new bike lanes the injuries more than doubled (260% higher) The report does point out that injuries in the rest of Cambridge fell 11.5% . So the reports are definitely not apples to apples. I also wish CBS and the city would stop referring to reports from other cities, across the country and the globe. Amsterdam is a favorite reference point. Cambridge needs to do its own analysis and make the call if streets are safer or not. in order to do that the crash data collection needs to be improved to capture bike-pedestrian crashes, bike bike crashes. I saw one recently where a cyclist tried unsuccessfully to pass another cyclist who swerved into the other. When I saw the cyclist try to pass I thought this is an accident waiting to happen and it was. (Both riders seemed okay) Right now only crashes involving a motor vehicle are captured. Also need to distinguish between crashes with pedal bikes and ebikes.
@NC Walker
That is totally false. The Federal Highway Association study of the bike lanes here in Cambridge showed that the bike lanes reduced accidents by 50%
@NC Walker
The Hanratty “report” has been thoroughly debunked. It is an amateurish mess that would never and will never be published by any credible journal.
That report used the *wrong data*. They failed to take into account increases in traffic. That is enough to render their conclusions invalid. But they also failed to use correct control comparisons.
The Hanratty report is nonsense. It made errors that would be caught by a freshman in an Introductory class.
By contrast, the recent FHA report used the right data and proper methods. That’s because it was done by *actual experts* who know what they are doing, not by a bunch of amateurs with an axe to grind. The FHA report showed the opposite results.
Thanks for writing and sharing this. I really appreciate the graph, and how clearly it demonstrates the correlation between increased miles of bike infrastructure and reduced crashes. A really compelling direction for us to move in as a city (and beyond, as other cities in the region follow in Cambridge’s footsteps).
@AvgJoe Where dd you find definitive information on increases in traffic? I assume you mean cyclist traffic?According to the only fixed cyclist counter in Cambridge, the ecototem showed a decrease of 23% in cycling in the past year. There is no reliable accurate bike counting done by CDD on a city wide basis. They estimate volume based on taking counts every other year in September Tuesday- Thursday. One year the weather was bad so they did not count and took two counts the following year. I guess cyclists dont ride in the rain? Go to the CDD website and take a look. In other cities they have many many more fixed cycling counters 24/7/365. Not sporadic counting in good weather. So there is no way to support increased traffic.
There’s a ton of BlueBike data showing increased ridership in Cambridge.
@MC Resident
The city-wide bike counts are irrelevant. What matters is the change in bike traffic on the streets where the bike lanes are.
If you build a bike lane on a street, more cyclists will use that street because, well, that’s what bike lanes are for.
That is why you can’t look at the change in the *absolute number* of accidents, you have to look at the change in the accident *rate*. It’s the accident rate per mile traveled that matters, not the absolute number.
That is a fundamental flaw. It renders the conclusions of the CSFA study completely invalid.
I took urban planning classes in college. This is an error that an undergraduate would not make. If they did, they would get an “F”.
They made other errors as well. The CSFA study uses the rest of the city as a statistical control. That is totally wrong. You need to use a design approach with explicit statistical controls.
For example, they need to find “control” streets that are very similar to the “case” streets, and test for comparability based on land use, infrastructure, demographics of the neighborhood, traffic, pedestrian/cyclist activity, and other factors that affect crash rates.
In sum, the CSFA study is an amateurish mess that would be rejected by peer review at any credible journal. It would earn a college student an “F’ if it were a term paper.
@MC Resident
So, as you can see, analyzing traffic data is not simple. When amateurs like Hanratty from CSFA try to do it, they make fundamental errors that lead to erroneous conclusions.
As far as I can tell, Hanratty has zero experience or education in urban planning or analyzing this type of data. I also noticed that one of the “reviewers” they chose to evaluate their study is a *chemist* with no experience in urban traffic data.
BTW, you don’t get to choose your own reviewers. That is not how peer-review works. They even got that wrong.
The CSFA team were amateurs who had no experience with this type of data. It shows. Their study was a mess with multiple flaws.
@MC Resident I think you’re misunderstanding the city’s counts. The number they count doesn’t really give you an absolute number of how many people bike in the city (they’ve done surveys for that). But by counting in the same weather conditions at the same times, it lets you see year-over-year trends… assuming certain ratios stay stable. E.g. ratio of weekend to weekday riding needs to be stable, or sunny day biking to rainy day biking, or commuting to non-commuting. If all those ratios are stable, and you count repeatedly under the same conditions, you can get trend data.
Before the pandemic that assumption of stability was pretty reasonable; if those ratios changed, it was probably slowly. After the pandemic it’s a problem. In particular, working from home had a massive jump, resulting in a decline in people commuting by all means (car, bike, etc.). So the ratio of commuters to non-commuters is no longer the same as it was in 2019, and it’s probably still changing significantly year-over-year. And the city’s counts are specifically focused on times when people commute, so the shifting ratio distorts the numbers somewhat.
(For car drivers, as context, something like 20% of car trips are commuting to work, the rest are for other reasons.)
Broadway is 24/7, which is good, but it is not a great measure for other reasons, most fundamentally that it’s just a single location. You wouldn’t estimate car traffic in Cambridge based on counting cars on Broadway, you need lots of locations. In more detail:
* It’s a very commuting-specific location, so plausibly affected more by the change to work from home.
* It’s had some construction nearby (sewer conduit or something, but also some buildings I think?).
* More broadly, construction of separated bicycle lanes, as well as other factors, result in people shifting where they bike separately from changes in volume, and that’s not reflected if you only have one location. Same would be true for cars, people shift how they drive based on e.g. shifting congestion patterns.
BlueBikes data is also 24/7, and it shows a large increase in biking in Cambrige since 2019, but some areas of Cambridge can’t participate since they don’t have BlueBike stations yet.
It’s a hard problem!
In any case: there are plenty of people biking right now, none of whom deserve to be injured or killed. As the article above shows, separated bike lanes are making streets safer for people biking right now. So even without this information, we still need to continue building SBLs.
I wouldn’t say there is “no way to support increased traffic”. Some ways are better than others, certainly. For instance, one could check the Bluebikes data
https://www.bluebikes.com/system-data
which shows steady increases in bicycle traffic. Not a perfect proxy, but the most popular stations are almost all in Cambridge, and Bluebike riders make up only a small fraction of total ridership, as anyone can see on the roads. I’d trust those data much more than a single-point counter for indicating the direction of any trend.
The Hanratty report apparently fails to account for the fact that cyclists are going to choose new routes based on infrastructure improvements. It would be quite surprising if cycle traffic didn’t increase on improved streets and decrease on others. That’s one reason why the data presented in this article are more compelling: they show a clear system-wide safety improvement. Honestly, even if it’s true that improved streets show higher injury rates (I have my doubts), they are apparently still making the system as a whole safer for all modes of transport. And these are just the temporary, quick-build lanes that are placeholders for the actual best-practice infrastructure!
Of course, the pandemic had no effect on travel and traffic patterns and behaviors! So a rational person will look carefully at “proofs” that are conveniently used to buttress a point of view.
@Fourmacks You can look only at the 2016-2019 period if you are concerned about pandemic impacts. The results are the same: Cambridge was doing better than the state.
now if only bikers would actually use the bike lanes and stop riding on sidewalks dodging pedestrians or running red lights. All the more reason to license bikes to report violations. Why are bikers exempt when it is a moving vehicle that can hurt people? This is a special interest group with a loud presence. The traffic back up in some cases negate any effort to keep cars from idling and circling. And many bikes are from out of town cutting through as are cars. Curious on the break down of users by diversity, ethnicity, socioeconomic riders, age. seems in other issues these are the first questions for equity. bike lanes were pushed through without study or policy. Again, Council is guided by special interests with votes and lack of thoughtful planning. In any thing. We are always left with putting out brush fires. Why are Bikers so entitled?
@pete Much of what you said is inaccurate or false.
1. The bike lanes were NOT done with a “lack of thoughtful planning”. The bike lanes were years in the planning. There were multiple public meetings and modifications after feedback from the community. There was an impact study. Most importantly, Cambridge voters supported bike lanes through three election cycles.
2. Cars are a far, far greater threat to pedestrians. They kill 7000+ pedestrians every year in the US. Bikes kill virtually no one. Cars cause >90% of pedestrian injuries. You say “bikes *can* hurt people”. Well, cars actually do hurt people, way, way, way more than bikes.
3. Studies show that drivers break the law just as often as cyclists.
4. Cyclists are entitled? Because they want to share the road without being killed? The people who don’t want to share are the entitled ones. Cars have owned the road for decades. Now that others want to share it, they are entitled??
When you are used to privilege, equality seems like oppression.
5. Bike lanes do not cause more pollution by causing cars to idle. Study after study has shown that bike lanes reduce pollution and GHGs. The reason is simple. Bike lanes increase cycling. Every person on a bike is not in a car.
Protected Bike Lanes Increase Safety, Save Money And Protect The Planet, New Report Finds
https://www.forbes.com/sites/tanyamohn/2022/11/30/protected-bike-lanes-increase-safety-save-money-and-protect-the-planet-new-report-finds/
It might be a good idea to do some research and check facts before posting. Otherwise, you spread disinformation.