Tag Archives: safety

Some Dutch roundabouts

Dutch roundabouts have received a lot of publicity, notably here: https://bicycledutch.wordpress.com/tag/roundabout/

Roundabout design in the Netherlands has seen a long process of trial and error. A design used until bicyclists complained strongly enough about it placed the bikeway away from the circular roadway, but cyclists were required to yield. Here is an explanation of Dutch roundabout design developments.


The current preferred design places the bikeway away from the circular roadway, and motorists are required to yield, as shown in this video below. That clears up yielding issues.

Here is a video of a roundabout outside the city of s’Hertogenbosch, put forward as an example of good design.

There is a long discussion of this roundabout, among others, on Facebook.

This is a rather large roundabout at the intersection of major highways, and with moderate deflection on entry or exit.  Looking here in Google Maps,  it’s clear that the highway in the background at the left is a bypass around the city of s’Hertogenbosch — though not a limited-access highway like the one which appears in the distant background in the video.

This roundabout was constructed in connection with the new bypass road around the city. Google Street View from 2009 shows the roundabout under construction. A sidelight on this observation is that Dutch practice does consider motor traffic. Two of the legs of the intersection at the roundabout are new roads being constructed at the same time.

I’ve been told by a knowledgeable person that the  bikeways on either side of the highways are supposed to be one-way, but the only destinations along these bikeways are at intersections — reducing the temptation to ride opposite traffic.

The design requires a lot of space because the circular bikeway is  much larger than the circular roadway. The roundabout  is outside a city, but nonetheless, it appears that several houses had to be demolished or moved to make way for this roundabout.

The installation here  places separate bikeways (red asphalt) and walkways (paver blocks) outside the circular roadway. Bicycle traffic shown in the video is light. If bicycle traffic were heavy, it would result in  congestion of motor traffic because motorists yielding to cyclists could not enter or exit the roundabout. Having a path (or for that matter, crosswalks) around the outside of a roundabout obviates the main advantage of the roundabout, that traffic can keep moving. Only grade separation would avoid this for both bicyclists and pedestrians. Motor vehicles and bicycles sharing the roadway would avoid the bicyclists’ causing congestion, but would not be as attractive for bicyclists lacking in skill and confidence..

If you look at the video full-screen, you can see a number of details which are not evident in the small window on this page. I am most interested in the interactions and negotiations for right of way, which are the central issue with mobility and safety in any intersection which is not traffic-signal controlled.

Expectation in the Netherlands is that motorists will yield wherever they see shark-tooth markings. The path around the outside of the roundabout is brought out to the entry and exit roads at a right angle and far enough outside the roundabout so that motorists will be able to see approaching bicyclists. Ohio resident Patricia Kovacs has investigated roundabouts in that state and demonstrated that motorists don’t even yield to pedestrians. She has posted some comments about roundabouts on this blog and in the Facebook thread mentioned earlier.

Some cyclists in the s’Hertogenbosch video are shown looking to their right as they pass paths coming in from their right, for example at 0:55 and 2:25, but many are shown not turning their heads to look for conflicting motor traffic. That is to say, they are putting their complete faith and trust in motorists to yield to them, which is a comment on Dutch expectations for motorist conduct. There is an especially stunning example of this at 1:59, where a cyclist powers through an intersection as motorists approach from the left, inside the roundabout, and the right, entering it. However, at 6:07, a motorist stops abruptly at an exit to the roundabout as a fast cyclist comes around from the right.

One cyclist leaves the roundabout on the left side, opposite the intended direction, at 1:38 in the video.  Another is riding around the roundabout clockwise at 2:40 and apparently while talking on a mobile phone.

At 2:34, a motorist is shown slowing to yield to a cyclist who turns right rather than to cross the exit of the roundabout. With no lane changing or negotiation betwen motorists and cyclists, the motorist did not have a way to know which way the cyclist would go.

Cyclists carry various objects in their hands or on the handlebars. At 6:40, a cyclist is carrying something which looks like a hockey stick.

At 7:18 a young woman has a disabled bicycle and is walking.

Now let’s look at some other Dutch roundabouts.

A roundabout inside s’Hertogenbosch, here,  has the bikeway immediately adjacent to the circular roadway, so that cyclists are hidden directly behind — not next to — exiting vehicles. The video shows motorists required to yield to cyclists in spite of this right-hook threat.

Here’s the video of the roundabout. Are the cycling facilities safe, as claimed? Or if safety is achieved here, is it maybe achieved in another way? You decide.

The description of the video indicates that this roundabout is rather new. Its design appears to be restricted by the small available space at an urban intersection.

Some notable interactions:

At 0:20, a car brakes rather abruptly. Shortly thereafter, a motor scooter passes through the roundabout on the roadway.

At 0:30 and again at 0:53, a car blocks the bikeway to allow a pedestrian to cross in a crosswalk which is just outside the bikeway.

Most bicyclists are not paying any attention to the traffic in the roundabout, At 0:45, a bicyclist is looking down at a cell phone, but at 0:50, 1:10, 1:29, 1:53, 2:03 and 2:10,  and a few additional times, bicyclists perform a shoulder check. The one at 2:03 does this while also carrying a cell phone in one hand.

At 1:49 and again at 2:20, there is a motorcycle in the bikeway, waiting along with bicyclists to enter the roundabout, and there is a bicyclist standing over his bicycle, facing opposite the direction of traffic.  It appears that he is having a conversation with the motorcyclist and a couple of pedestrians. They are blocking the crosswalk.

At 2:49, a motorist stops in the roundabout to yield to a bicyclist who does not cross, but instead turns right. The bicyclist gives a right-turn signal, but too late for the motorist to react, and in any case, a prudent motorist would not risk that the bicyclist would go straight even though signaling. The design of the roundabout does not make the bicyclist’s intentions obvious.

At 2:58, a bus barely outpaces a bicyclist through the roundabout. The bicyclist turns right, but the bus driver has no way to know that he will. The bus driver is either very highly skilled at judging the bicyclist’s speed, or reckless. The bicyclist would have had to yield to the bus if going slightly faster and continuing around the roundabout.

Starting at 3:00, several bicyclists enter traveling the wrong way on the bikeway or sidewalk. Some turn right but others pass close to a doorway which a pedestrian has just exited, and a blind corner, and cross from right to left in the crosswalk or bikeway. An articulated bus enters the roundabout and these bicyclists pass behind it. Other bicyclist traveling counterclockwise around the roundabout will have to yield to the long bus, though this occurs outside the field of view of the video.

At 3:45, bicyclists share the bikeway around the roundabout with a skateboarder and motor-scooter rider.

Almost all the bicyclists are pedaling about 40 rpm.

Here’s a roundabout where bicyclists go around square corners: http://goo.gl/maps/lxfc2

And a little roundabout with advisory bike lanes at some of the entrances: http://goo.gl/maps/HK908

In the so-called “shared space” roundabout in Drachten, cyclists share space with pedestrians. The meaning of the term “shared space” is very different here from its more usual meaning, that motorists, bicyclists and pedestrians all operate in the same space.  In the Drachten roundabout, bicyclists and pedestrians share space — as on shared-use paths in the USA — but are strictly separated from motor traffic except in crossings, as in the other Dutch roundabouts. The space around the margins of the Drachten roundabout also serves as a pedestrian plaza.


I’m poking around in YouTube and Google maps. Here’s a roundabout in YouTube — http://www.youtube.com/watch?v=EXUF97p8fXQI — location not given, as is usual in such promotions, but I found it in Google Maps by searching on the name of one of the businesses nearby: http://goo.gl/maps/Jd2ED. A special feature made the roundabout practical: the buildings are set far back at a 45-degree angle on each corner. The circular bikeway around the outside makes it possible for motorists to see cyclists in order to yield (though motorists don’t always, as the video shows) and greatly adds to space requirements, which already are large for a roundabout. There wouldn’t be room for such a roundabout at many urban intersections.

Here’s a blog post which includes the video just described and others of the same roundabout, and describes different types of Dutch roundabouts. http://bicycledutch.wordpress.com/2013/05/09/a-modern-amsterdam-roundabout/

Another roundabout in Amsterdam is of the spiraling Turbo Roundabout design, with a path close around the outside and scary sight lines which place a cyclist too far to the right to be in view of a motorist exiting the roundabout: http://goo.gl/maps/fQybJ and street view, http://goo.gl/maps/LU1ww . Traffic signals have had to be placed at the exits to mitigate these conflicts. This is a triple roundabout with a tramway going around the inside, also requiring traffic signals.

The left and center roundabouts in this overhead view, http://goo.gl/maps/Q3jIy also are of the bikeway around the outside type: but the rightmost one, in a wooded area, is of the newer type.

Dutch roundabouts are  of several types for motor traffic, but the major difference for bicyclists is whether they travel around the outside of the roundabout, or there are grade separations. There are no examples like the small modern roundabouts and neighborhood traffic circles in the USA, where bicyclists share the roadway with motor vehicles.

Here is an example of grade separation: https://bicycledutch.wordpress.com/2011/05/26/multi-level-roundabout-the-safest-solution-for-a-junction/

And here is a showcase example of grade separation — replacing an installation much like the one shown in the first video embedded in this post : https://bicycledutch.wordpress.com/2012/08/23/spectacular-new-floating-cycle-roundabout/

Roundabouts are expensive and take up a lot of space.  Many of the promotions we are seeing of Dutch facilities ignore these limitations and the compromises they exact and/or celebrate the newest and most impressive examples.

PeopleforBikes Interprets Boulder Data

Here’s a quick review of an article by Michael Andersen of the PeopleforBikes Green Lane Project about the City of Boulder, Colorado’s removing what he calls a “protected bike lane”. I prefer to call it at barrier-separated on-street bikeway, avoiding a value judgment. Let’s see what the article in fact establishes.

graph in streetsblog article

Graph in Streetsblog article

According to the graph (copied above) and numbers in the article, the installation achieved a major reduction in collisions between motor vehicles at the expense of a 2.5 time increase in motor-vehicle-bicycle collisions. The article states that bicycle volume went up by 54%, and so the car-bicycle crash rate went up by about 1.6 times. Most car-bike crashes in urban areas involve crossing and turning movements. Forcing motorists to cross a bikeway to enter a travel lane, and forcing bicyclists and motorists to start turns from the wrong side of each other, make these crashes more difficult to avoid.

But the story gets more interesting if you click on the article’s link to city data. The left pie chart at the bottom of the city-data infographic shows crashes per year before the installation and the right pie chart, crashes per week following the installation. There were, on average, 11.3 car-bike crashes per year before the installation and 3 in 8 weeks, about 20 per year, afterward. That comes out to an increase of about 1.7 times, but the afterward sample is very small (3 crashes) and seasonal variation isn’t accounted for. The comparison has no validity.

Now look again at the graphs in the article. They don’t accurately reflect these numbers. The “before” bar reports about 0.15 car-bike crash per week or 8 per year, not the 11.3 per year in the pie chart, and so the graph shows an increase in bicycle crashes even greater than the numbers would suggest .

So, to sum up, the article reports a reduction in car-car crashes, but a large increase in car-bike crashes — while defending the bikeway as “protected” and failing to note that there isn’t enough “after” data to produce any statistically valid comparison.

Oh, and there’s also this, on the second page of the infographic:

“The bicycle volume increase along the corridor is consistent with the increase the city typically sees when school is back in session.”

The cyclist counts, unlike the crash counts, are robust. About half the increase is attributable to the school’s being back in session, not to installation of the separated bikeway — a point which Andersen neglects to mention.

To sum up:

What does the article say about the safety of the Boulder facility? Nothing. No conclusion can be drawn from the data, but despite that the Green Lane Project shot itself in the foot with a graph showing a large increase in bicycle crashes.

What does the say about bicycle use? Maybe an increase of 20% or so due to installation of the bikeway, though some of that may only have been transferred from another street.

What does the article say about the quality of Green Lane Project journalism? I think that I’ve made my point but you can answer that for yourself.

Alice Swanson fatality, a right hook

Here is the intersection in Washington, DC, where cyclist Alice Swanson was killed by a right-turning garbage truck.

The Street View is from 2009, as close as Google gets to the year of the crash (2008). The big cross street is Connecticut Avenue. The little one before it is 20th Street NW. My recollection is that the garbage truck turned right into 20th Street, and Swanson probably assumed she could pass it safely because it would turn right onto Connecticut Avenue and the traffic signal was red. If you open the Street View in Google Maps and click on the clock at the upper left, you can go to Street Views from different times and see the intersection without a bike lane (2007) and with green paint (2014). The dashed bike lane stripes indicate that motorists are supposed to merge into the bike lane, but many do not and it may not even be possible with a large truck. Note also that parking extends close to the intersection — the last 20 feet or so are no parking, with a fire hydrant.

I get a hug during CyclingSavvy instructor training.

I have operated my bicycle essentially as a driver since 1978, when I read an early edition of John Forester’s book Effective Cycling. Since 1982, I’ve been an Effective Cycling Instructor, then League Cycling Instructor, in the League of American Bicyclists educational program, which got its start with Forester’s work.

In the 1980s, Forester’s instruction about road use was state-of-the-art. Over the years, there have been changes to teaching techniques and content, some for the better and some for the worse, some from inside the League’s program and some by individual instructors,  but I think that it is fair to say that there has been no systematic revision and upgrade to the content about bicycle driving.

On the weekend of March 3-5, 2017, I took instructor training in a different program, CyclingSavvy, in Orlando, Florida.

CyclingSavvy Instructor Training, March 4, 2017. Instructor Trainers keri Caffrey and Lisa Walker debrief instructor candidates following a "feature" -- a ride through a demanding stretch of roadway.

CyclingSavvy Instructor Training, March 5, 2017. Instructor Trainers Keri Caffrey and Lisa Walker debrief instructor candidates following a “feature” — a ride on a challenging stretch of roadway.

CyclingSavvy is a program of the American Bicycling Education Association, with an emphasis on urban cycling. In my opinion, CyclingSavvy classes are more focused and effective than the classes in the League of American Bicyclists program.

A CyclingSavvy class can be difficult for long-time League Cycling Instructors, in part because we have, well, ingrained ways of doing things. I took a CyclingSavvy class in August, 2011, in Portland, Maine. It was a bit of a rough experience. There were misunderstandings, especially on a group ride before the class: about lane use — at one point I asked “what are we doing this for?” and about the purpose of the ride. (My video camera setup is important enough to delay the ride start?) I came off that class with a lukewarm endorsement at best to work toward being an instructor.

In the years since then, I’ve been privileged to develop a closer relationship with CyclingSavvy, by reading materials online, attending two conferences and working on a CyclingSavvy edition of my Bicycling Street Smarts booklet (still awaiting publication as of this writing).

I’ve learned quite a number of things from CyclingSavvy that were new to me. To name some:

  • more assertive lane positioning;
  • group lane changes from the rear;
  • how to instruct novice cyclists so they will ride as an organized group;
  • waiting for the green light to turn right, so as to turn onto an empty street;
  • Turning into the destination lane for a left turn immediately on turning right;
  • plotting strategies for lane use with Google Maps;
  • teaching techniques effective in effecting behavior change;
  • time management when teaching.

I got a solid recommendation to go for  CyclingSavvy instructor training last October — studied up — it’s demanding! — and took the training, March 3-5.

At one time during the parking lot session of the training, I said: “I’m humbled with what I’ve learned that’s above and beyond what I already knew.”

Which is true.

Trainer Lisa Walker then  came over to me and gave me a hug.

I’ve been asked to describe what led to the hug. And this has been my explanation.

The takeaway from my experiences: I recommend that League Cycling Instructors, especially long-time ones, take special care to familiarize themselves with the differences between their practices and those of the CyclingSavvy program. That study can be illuminating, and can make the difference between failure and success in the CyclingSavvy program. You might get a hug too!








About the bicycle radar reflector Kickstarter campaign

This is commentary about a Kickstarter campaign for a radar retroreflector integrated into a bicycle taillight assembly.

An image from the Web site:

Image from Ilumaware Web site

Image from Ilumaware Web site



One nice thing I can say about the product is that it is quite inexpensive, so I’ll say that first. The reason is that this is not a high-tech product. This is a low-tech component of a system whose high-tech component is in cars.

Retroreflectors work by concentrating light (or in the case of a radar reflector, radar signals) back toward the source. The product is a single cube-corner retroreflector. Optical retroreflectors are the insect’s eye version, with multiple smaller reflective elements, so they work at the much shorter wavelengths of visible light. The technology is described on another Web page.

As to the effectiveness of this product, I have no doubt that it improves the visibility of a bicycle to radar — but…

The product’s Web site repeatedly uses the term “OTR technology”, without ever spelling out the meaning of the acronym . I couldn’t find a definition anywhere online, either. This term makes the product appear more high-tech than it is. Indeed, the site claims:

Stealth techniques use radar reflection to make an object less visible and/or “invisible” to radar. We have reverse engineered this technique into a product used by a cyclist to make you more visible to a car. This is a revolutionary application of radar technology.

Reverse engineering is correctly defined as analysis of an undocumented product to develop specifications for a duplicate or similar product. Examples are the Wright brothers’ reverse engineering the flight characterisics of birds to design aircraft, and Linus Torvald’s reverse engineering the proprietary Unix computer operating system to construct the Linux operating system. The Kickstarter campaign uses the words “reverse engineered” inaccurately, so as to mislead people who do not understand it, as if to mean design of a product to have the opposite effect of an existing product. And when that product is a stealth bomber — wow, now the new product must be extremely high-tech! Again, the product is a simple cube-corner radar retroreflector, as has been used in boating for decades. The designers describe design and optimization of their product, but this is plain vanilla engineering, not reverse engineering.

A radar retroreflector which works in all directions is more desirable, (though it still will not always work, even if a car has radar, because the radar beam may not be aimed in its direction, and there may be a line-of-sight obstruction).

Radar alone as a robotic aid to a human driver is possible, but not very practical. Only a small percentage of cars have radar as of yet. A human driver uses visual cues. A fully-robotic car also must, because not every potential obstacle will be as large or reflect radar signals as well as a bicycle — think potholes, cats and dogs, etc.

The product, as shown on the Web site, includes an active taillight, but no optical retroreflector — though installed in the same location on the seatpost which is usual for one — following in the long tradition of new products promoted as a panacea for cyclists’ conspicuity problems while ignoring basic legal and functional requirements. Most states require a retroreflector or taillight, but any taillight can go out without the bicyclist’s being aware of that, and so any bicyclist who rides after dark should have a rear-facing retroreflector, not only a taillight.

The online promotion entirely fails to mention the need for a headlight, or the legal requirement for one. The Web site shows a bicycle with no headlight.

A bicyclist must always use a headlight at night, because an optical forward-facing reflector does not alert pedestrians or drivers who do not have headlights aimed at the bicycle (cars backing out of driveways, at stop signs in side streets, other bicyclists without headlights, etc.) Still, unlike the optical retroreflectors on bicycles, a forward-facing radar retroreflector is likely to be effective, because a car’s radar is likely to scan in more directions and its pulsed output is immune to interference from other sources. But the retroreflector here is only rearward-facing.

The online promotion also makes a number of inaccurate statements.

 Riding with a tail light [sic] is important regardless of the time of day.

While a very bright taillight can help to alert drivers — human or robotic —  during daytime, reducing the probability of a collision somewhat, there is no law requiring a taillight (or rear-facing optical retroreflector) when riding during daytime.

* “In 2015, more than 35,000+ collisions occurred between cars and cyclists in the U.S. Approximately every 3 minutes, world-wide, 6 people die and nearly 285 people are injured in collisions involving cars and bicycles. The majority of these accidents are from behind because drivers didn’t see the rider and it is NOT because they did not have a tail light.”

This is wildly inaccurate. While rural car-overtaking-bike collisions are disproportionately serious and fatal, only approximately 7% of car-bicycle collisions in the USA are car-overtaking-bike collisions. A very large percentage of these occurs to cyclists riding at night without a taillight! In urban areas, most of the serious and fatal collisions involve turning and crossing movements. No rear-facing conspicuity equipment —  optical or radar retroreflector, or taillight, will prevent most of these. Sure, many if not most car-overtaking bike crashes could be avoided, day and night, by use of a radar reflector, if cars have radar connected to a robotic crash avoidance system — but again, as of yet, only a very small percentage of cars is so equipped. Which takes me to my next quote:

* “In 2016 … there are 470 out of 566 unique car models sold in the U.S. equipped with radar (83%).”

This is very seriously overstated. Saying that a model is equipped with radar is not the same as saying that radar is standard. Adaptive cruise control is still often an expensive option. Only some adaptive cruise control systems include automatic crash avoidance. Some systems use laser ranging rather than radar. The fleet of motor vehicles turns over slowly. More even-handed estimates are found in this article in the Detroit News. Quote from that article:

IHS Automotive forecasts 7.2 percent of vehicles produced globally by 2020 will feature adaptive cruise control, up from 2.2 percent in 2014.

More details and a list of vehicles are on Wikipedia.

Why do promotions like this occur? Fundamentally, because regulation of bicycle equipment in the USA at the Federal level, where equipment standards are set, is a Wild West situation, harkening to the interests of the bicycle industry. That is another story, too big to cover here.










Boston expert design

Here’s a video of the intersection of Commonwealth Avenue and St. Mary Street, Boston, Massachusetts, USA, an example of the design expertise which earns Boston its place with the League of American Bicyclists as a Bicycle Friendly City.

The video is from 2013. As of 2016, one change has been made: the zigzag in the bike lane has been replaced by a diagonal transition.

The idea that cyclists should turn across in front of multiple lines of motor vehicles to change lane position is not unique to this location. Here’s another example, and it is by no means the only other one:

I have a blog post in connection with that video too.

Duck Boat crashes

We had a duck boat run into a motor scooter from behind on Saturday, May 7, 2016 in Boston, killing one of the riders. It isn’t clear from the news story why this happened, though I expect that the poor forward visibility from the duck boat was a factor. Did the motor scooter operator pull ahead of the duck boat, riding and stopping in its large blind spots? Or did the duck boat operator run into the back of the motor scooter in spite of its being in hiss field of view? As usual with crashes involving two-wheelers — bicycle, motor scooters, motorcycles — and despite there having been many eyewitnesses, the Boston Globe offers no information as to the cause of the crash. Investigation is underway, although if it proceeds as with recent bicycle crashes, detailed results may not be made available for a long time, if at all.

Another duck boat crash occurred in Seattle, 5 killed, 62 injured — but that one was due to failure of an axle, which sent the duck boat into the side of a bus in an oncoming lane of traffic.

What is to be learned from these crashes?

For one thing, the duck boats are surplus from the Second World War. Though they served gallantly in that war, they are over 70 years old now: mechanical failures are not out of the question. The duck boats’ design as amphibious vehicles placed the driver high above the road over a high hood, with poor visibility to the front — a problem which has led to fatalities of pedestrians in crosswalks with large trucks. The duck boats do not have a front bumper, but instead, have a hull which can push unfortunate pedestrians, cyclists and vehicles underneath. These vehicles probably would not be legal, except that they are antiques.

Another issue with the Boston crash may be of education. Did the motor scooter driver not understand the peril of riding in blindspots of large vehicles? Boston is relentlessly installing bicycle facilities which direct bicyclists to ride into blindspots. It does not appear that the collision involved any such installation, but motor scooter operators are permitted under the law to use them, and their existence, along with a lack of instruction as to their perils, contributes to hazardous behavior elsewhere as well.

In the context of all these issues, my misgivings about the Vision Zero campaign described in the Boston Globe on April 17 need no further mention.

The Slow Ride, redux

Bob Sutterfield writes:

I don’t ride fast so I can participate safely in traffic. I participate in traffic so I can safely ride fast enough for my needs.

If I were to ride in the gutter, on the bike path, in the door zone, on sidewalks and cycle tracks, etc. I could reduce my risk (probably to an acceptable level) by traveling slowly – at near-pedestrian speeds. That slower speed would give me more time to react to the hazards present in those environments.

But I use my bike for purposeful travel. I don’t have time in my day to travel as far as I need to go, if I were constrained to moving only at near-pedestrian speeds. In order to get where I’m going in a practical amount of time, I need to be able to ride at the speeds I’m capable of sustaining on a bicycle. And I need to do it more safely than if I were in the gutter or on a bike path or in the door zone – I need the safety and convenience of the travel lane. That speed is what the travel lane is designed to accommodate, and that’s what the ordinary traffic laws are designed to enable.

If my choice of travel by bicycle is restricted to hazardous areas like gutters and bike paths and cycle tracks, I’ll choose another way to travel – something motorized so I don’t suffer those restrictions.

Lane Control on Lexington Street

Here’s a video showing a bicycle ride on a constant mile-long upslope, at speeds of 10 to 12 miles per hour (16 to 20 km/h), on a suburban 4-lane speedway with narrow lanes and no shoulders, the most challenging street in the community where I live. Motor taffic was very light, and auite fast. Points made:

  • Lane control is not about riding fast: it is about controlling one’s space.
  • Lane control is necessary so motorists will overtake at a safe lateral distance on a street with a narrow right-hand lane.
  • By requiring motorists to make full lane change, lane control lets a cyclist with a rear-view mirror confirm well in advance that motorists will overtake with a safe lateral distance.
  • With the light traffic on a multi-lane street, a slow bicyclist does not cause any significant delay to motorists.
  • Most motorists are cooperative.
  • A few motorists are abusive — even though they can easily overtake in the next lane —  but they too overtake safely.
  • American traffic law supports lane control.

Lane Control on Lexington Street from John Allen on Vimeo.

M. Kary on the epidemiological approach to traffic-safety research

M. Kary has released the manuscript of his paper on the unsuitability of the epidemiological approach in studying traffic safety.

Unsuitability of the Epidemiological Approach to Bicycle Transportation Injuries and Traffic Engineering Problems
Author: M Kary
Injury Prevention 2015;21:73-76, Published Online First 14 August 2014

First paragraph of the abstract:

Bicyclists and transportation professionals would do better to decline advice drawn from characteristically epidemiological studies. The faults of epidemiology are both accidental (unpreparedness for the task) and essential (unsuitability of the methods). Characteristically epidemiological methods are known to be error-prone, and when applied to bicycle transportation suffer from diversion bias, inappropriately broad-brush categorisations, a focus on undifferentiated risk rather than on danger, a bias towards unsafe behaviour, and an overly narrow perspective. To the extent that there is a role for characteristically epidemiological methods, it should be the same as anywhere
else: as a preliminary or adjunct to the scientific method, for which there is no

You may read the entire manuscript here: