Tag Archives: bikeway

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.

http://bicycledutch.wordpress.com/2011/05/12/priority-for-cyclists-on-roundabouts-in-the-netherlands/

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.

http://www.youtube.com/watch?v=B88ZVrKtWm4

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.

Protected?

The cyclist’s comment on this Youtube video: “This is why turn signals are important. Had she used a turn signal, I would have stayed back and let her turn. But because she didn’t use one, I assumed she was going straight.”

Let’s take a look into the situation.

The car was initially stopped, second in line at a traffic light. Then the light turned green. The cyclist was approaching in the separated bikeway from the car’s right rear, off to the side. As the motorist initiated her turn, the cyclist wouldn’t be visible in the motorist’s passenger-side rear-view mirror. The motorist would have had to turn her head sharply to the right to see the cyclist, but she needed to look ahead to steer and avoid other potential conflicts. Yes, she should have used her turn signal, but again, she was supposed to yield to the cyclist, not the other way around, and the location of the bikeway made it easy for her not to notice the cyclist.

What are solutions to this problem?

* Well, certainly, drivers should use their signals.

* Bicyclists need to be aware of these conflict situations, and it’s best not to make assumptions.

* Bikeways like this create the appearance of safety because they assuage “fear to the rear” but in urban and suburban areas, most car-bike crashes are due to crossing and turning conflicts, including the one shown in the video, the classic “right hook” — and also the “left cross” (car turns left into the path of an oncoming cyclist). This is a two-way bikeway on one side of a street and so it placed the cyclist farther outside the view of the turning motorist, and can also lead to “Left hooks” and “right crosses”. Germany no longer recommends two-way bikeways like this, as the safety record has proved to be especially poor.

* To avoid these conflicts, the bikeway needs an exclusive signal phase when other traffic doesn’t turn across it. But that will result in more delay for bicyclists and motorists alike. This bikeway also crosses driveways where the barrier is interrupted.

* A bikeway in a corridor separate from streets, a bike route on lightly-used streets, ordinary striped bike lanes or wide outside lanes avoid the problems with a separated bikeway.

The location, in Seattle, Washington, USA.

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.

Montreal sidepath protects?

A classic right-hook collision occurred on August 26, 2015 in Montreal, where the cyclist was riding on a sidepath.

Here’s a news report on the crash.

As I’ve said repeatedly, sidepaths do not prevent crossing and turning collisions.

The sidepath in this crash is in a block folliwng a steep downhill. The cyclist might have been  overtaking the truck which turned right across his path.

I have cycled through the crash location and shot a video of my ride. It is here.

Rue Berri from Cherrier to de Maisonneuve, Montreal from John Allen on Vimeo.

Michael Colville’s Pitch

About the video here by Mikael Colville of copenhagenize.com:

Mikael Colville’s talk in the video is introduced by a video clip of a rather sorry infrastructure situation, with a crowd of bicyclists slowly making their way forward, cramped in a narrow passage to the right of an opaque barrier, while a line of cars turning right must yield to the cyclists after turning past the barrier. To me, this choice of a clip conveys the message “look, we are morally superior, motorist, we’re going to make it hard for you: you have to yield to us.” It doesn’t say anything about making bicycling more convenient, or anything but a nuisance to people who might think of switching from motoring. Or that whoever chose this location had any other sense about infrastructure — certainly none about sight line hazards.

And the music — the Rolling Stones’ Sympathy for the Devil! Now there’s an odd choice!

Similarly, at the end, there is an overhead drone shot of a bridge which has recently been restriped from four to two lanes of motor traffic, to add street level bike lanes next to already existing bikeways behind curbs. The implication is that bicyclists are winning by taking space away from motorists, and that space is to struggle over, not to share. In this case, on a bridge, I’d agree that bike lanes are suitable, but are four needed? What happens where they turn off at the end of the bridge while motor vehicles can go straight? We don’t see. Who knows?

The talk is all about marketing. The core of his message is that guilt-tripping people about environmentalism doesn’t work, and we must use marketing to make bicycling look attractive. Two products which Colville discusses for purposes of comparison, sewing machines and vacuum cleaners, are both highly useful labor-saving devices which quickly became popular for that reason, but he doesn’t mention that. He does praise improvements which made them more compact and useful in the home, but mostly, he praises the decorations on sewing machines which made them more attractive to homemakers.

My mother owned a Singer treadle sewing machine, and indeed it was a beautiful product — to some degree because of the flower stencils but also because of its elegant product design, with a table to hold supplies and attachments, and into which the machine could be folded down to make the table useful when the machine wasn’t in use. Treadle power was perfect for the pre-electrical era, and the wheel on the right end of the machine could start, slow or stop it with precision. Not to speak of my mother’s machine’s being several decades old and still working perfectly.

My mother also owned a 1950-ish Kenmore (Sears brand, made by Electrolux) vacuum cleaner, and it was an esthetic horror, shaped like an airplane fuselage, painted dull gray and very loud. She made much more use of the vacuum cleaner than of the sewing machine.

Colville says that we must market bicycling like these products. He deprecates “the 1%” of people who will wear fancy cycling clothing” — guilt by association with political class struggle, divisive, and also a reference to the categorization which Roger Geller made up, pulling the numbers out of his head, only to be followed up by a home-town study which found that his numbers were exactly right (surprise!).

Colville says that people are conservative and don’t want to stand out. But, tattoos peek out from under his plain white T shirt.

I don’t think that bicycling can be sold by marketing alone. It must be practical and useful like a sewing machine or vacuum cleaner, or people won’t use it for daily transportation. Though some people like to show off with Spandex and carbon fiber bikes, others wear street clothes and ride beater bikes. Some do both. Should instructors even care? We make bicycling more practical for any cyclists by helping them to do it well — and offering informed opinions on what works, or not, in bicycle planning and infrastructure.

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.

Bruce Epperson’s observations on transportation funding

Bicycle historian Bruce Epperson has written a paper examining trends in transportation funding in the USA from the 1960s to the present. It makes interesting reading. With his permission, I have made the paper available in PDF format on this Web site:

http://john-s-allen.com/pdfs/epperson-funding.pdf

Another crosswalk confusion, and a fatality

In response to my post about confused yielding requirements where shared-use paths cross streets, Ryan Reasons has published comments on a recent fatal truck-bicycle crash in the Seattle, Washington area.

The photo below is from the KOMO TV/radio station news photo gallery.

view of crash scene

View of crash scene

My response to Ryan’s comments went into enough detail that I have decided to make a post of it. My response follows his comments below.

Ryan’s comments

@John S. Allen
The sort of confusion you describe may have cost Gordon Gray his life last Wednesday after he collided with a cement truck. The sheriff’s department says that Gray, a 70-year-old bicyclist from Washington state, was cycling on a MUP when he ran a stop sign, entered a street running parallel to the MUP and was struck.

King County Sheriff’s Sgt. Stan Seo says the Kenmore man was biking southbound on 65th Avenue Northeast Wednesday morning when he was hit by a cement truck heading west on Northeast 175th Street. Seo said Friday that according to investigators, it appears the cyclist did not stop at a stop sign and was hit in the intersection. He says the cyclist had turned off the Burke-Gilman Trail shortly before the accident.
The Associated Press, Komonews.com

If one accepts Sgt. Seo’s account of the events leading to the collision, then Gray was cycling on the MUP when he turned onto 65th Avenue to enter Northeast 175th street. (See this Google street map.) [You may  click on the link to open the view in Google maps, or click on the image below  to enlarge it — John Allen]

Location of Gordon Cray crash

Location of Gordon Gray crash

Note that the Google map shows three stop signs of possible relevance. The stop sign on 65th Avenue is located just north of the MUP and crosswalk. The other two stop signs are located on the MUP at opposite ends of the crosswalk.

Once Gray entered 65th Avenue from the MUP and headed south, did Gray have a legal obligation to stop at the stop sign on 65th Avenue? I don’t think so, because after turning south onto 65th Avenue the stop sign was behind Gray and facing north.

Let’s assume Gray committed a traffic violation (running a stop sign) when he turned from the MUP onto 65th Avenue. Does that mean Gray is legally at fault for a collision which occurred on his subsequent turn from 65th Avenue onto Northeast 175th Street?

The account given by local law enforcement suggests Gordon Gray will be blamed for his own death, even if Gray is not fully at fault. That seems like an injustice for Gray, an undeserved vindication for confusing cycling infrastructure, and fuel for more of the ugly jeers that accompany the deaths of cyclists who truly are at fault.

My response:

This is an interesting situation, and especially so as cyclists’ exiting from bikeways into parallel streets becomes more common with the increasing number of sidepaths (or “cycle tracks”, or so-called “protected bike lanes”). The path in question runs parallel to and just north of an east-west street (Northeast 175th Street) and crosses another street (65th Avenue) which Ts into it from the north, with a marked crosswalk. There are stop signs for the path at either end of the crosswalk, and there is a stop sign on 65th Avenue Northeast before the crosswalk, as is usual. So, once Gordon Gray was in the crosswalk, there was no stop sign directing him to stop at Northeast 175th Street.

This is not the same situation I described in the earlier blog post. What I described is the confusion from having stop signs at the ends of a crosswalk. Traffic in the street is supposed to yield to pedestrians in the crosswalk but confusion arises because the stop signs indicate that cyclists in the crosswalk must yield to traffic in the street it crosses. These two requirements contradict one another. The confusion manifests itself in drivers on the street stopping and yielding to cyclists, whom the stop signs direct to stop and yield to the drivers in the street. It is unclear who may proceed. In practice, the cyclists usually proceed, and often without coming to a complete stop, but also cyclists are faster than pedestrians, and a motorist’s stopping often requires a cyclist to stop when they would otherwise not have to, because the motor vehicle would have passed before the cyclist reached the crosswalk. There are also the issues which occur at other crosswalks, that the first motorist in one lane may stop, but a motorist in another lane may not, requiring extra caution of cyclists due to their higher speed and longer stopping distance than those of pedestrians.

What you describe appears to be that cyclist Gordon Gray entered the crosswalk, and then entered the parallel street. Indeed, there was no stop sign facing him once he had entered the crosswalk, as he did not pass the stop sign for traffic on 65th Avenue Northeast. The legalities here are somewhat confusing. Probably the stop sign before the crosswalk did not apply to entry onto the parallel street. Was Gray required nonetheless to yield before entering the parallel street? He would have been, if he had passed the stop sign on 65th Avenue Northeast. A T intersection without a stop sign is an uncontrolled intersection, and so he would still be required to prepare to yield, perhaps also to yield: in some states, at least Massachusetts, where I live, stop signs are not posted where one street Ts into another, but yielding is required. A concern for self-preservation would also require being prepared to yield, whatever the legalities.

There are a few things which the news report does not indicate:

  • Which way was Gray going? Was he originally westbound on the path? Then he would have had to look behind himself for the truck.
  • Was he attempting to head eastbound on Northeast 175th Street (or westbound on the wrong side), and so he was attempting to cross in front of the truck?
  • Just what was the truck driver doing, or about to do? There is a large concrete plant with two driveways, across Northeast 175th street from 65th Avenue. Concrete mixer trucks in the same colors as those in the news photo are visible parked there in the Google Maps overhead view. It is possible, for example, that the truck driver was signaling a turn, suggesting to Gray that he would turn left into the driveway east of 65th Street Avenue Northeast, but instead was continuing into the next driveway when his truck struck Gray. The location of the truck in the photo at the top of this post suggests that.

Translation of complete paper on German bikeways 1897-1940

I’ve prepared a full translation of the important paper by Dr. Volker Briese of the University of Paderborn in Germany about the history of German bikeways from 1897 through the start of World War II. This has previously been available only in German, or in a highly condensed version in English in the narrowly distributed Proceedings of the 1993 International Cycle History Conference. You may read the English translation here, and also find your way to the other versions as well if they are what you would prefer.

Monsere, Dill et al. — Not Yet a Review, But…

M. Kary, who prepared a review of the Lusk et al Montreal study, has had a preliminary look at the Monsere, Dill et al. study of barrier-separated on-street bikeways (“cycle tracks”) which the bicycle industry lobby PeopleforBikes is promoting as demonstrating their safety. Dr. Kary has given me permission to publish his comments here.

An Introduction To and Overview Of:
Monsere C, Dill J, et al. (2014) Lessons From The Green Lanes: Evaluating Protected Bike Lanes In The U.S. Final Report, NITC-RR-583

To begin with a platitude: traffic accidents are rare events. The totals are large only because the overall volumes of exposure are huge. Therefore, if considering safety in terms of outcomes rather than the underlying mechanisms of operation, any facility, no matter how poorly designed, will appear safe if examined over a short period of time.

But collecting data over a long period of time has its disadvantages too: not just cost and delay, but also the averaging, and therefore blurring, of the effects of various changing causes and circumstances. Nor does it work at all for facilities that are yet to be built. In response to these problems, engineers developed the methods of traffic conflict analysis. They can be seen as based on the following logical and kinematic necessities. First, in order for a collision to occur, the vehicles involved must eventually get on a collision course. Second, in order to get on a collision course, they must first get on a near-collision course. On the other hand, not all vehicles once on collision or near-collision course do end up colliding: their operators make course corrections and avoid that outcome. Such potentially dangerous but often ultimately safe trajectories, i.e. traffic conflicts, occur much more frequently than actual collisions, deaths, or injuries. If there exists a suitable relationship between the former and the latter, then conflict analysis can be used to study road safety at reduced cost, with better timing, and even via simulation modelling of facilities that have been designed but not yet built.

The theory and practice of conflict analysis for motor vehicles has been developed over something like a half a century of research. This has evolved to quantitative methods using not just traffic cameras, but also instrumented vehicles, automated data extraction, and theoretical concepts such as time to collision, gap time, gap acceptance, post-encroachment time, and many others. There is no such corresponding body of research for bicycles. Even if there were, it could never be as important to bicycle or pedestrian deaths and injuries as it is for the occupants of cars and trucks: for example, the latter vehicles never topple over at stops or just slip and fall, so that their occupants fracture an arm or strike their heads on a curb. In fact the majority of bicyclist injuries, even those requiring hospitalization, apparently involve only the bicyclist, making conflict analysis entirely or at least largely irrelevant to them.

On the other hand collisions with motor vehicles are major factors in cyclist deaths and injuries, and they are what cyclists worry most about. And even apparently bicycle-only crashes can be provoked by e.g. general fears or specific intimidations, or avoidance manoeuvres leading to loss of control. Thus there are also dimensions of traffic conflicts applicable to bicycling, but either inapplicable or less so to motor vehicle-only conflicts. Nor is every conflict visible or strictly kinematic: consider for example the effects of sudden and loud horn honking or engine revving.

With these fundamental limitations in mind, obviously traffic conflict analysis is a promising method for investigating important aspects of bicycling safety. The theory needs to be developed, so we can figure out what constitutes a high or low rate of conflicts, what types of conflicts figure what way into which accident types, and how vehicle operators and pedestrians cope with them, such as through hypervigilance, or avoidance of the area and thus diversion of problems to a different one.

Not only does the theory need to be developed, but also the methods of data extraction and analysis: the subjective review of traffic camera recordings, typically of low quality, is a mind-numbingly tedious, labour-intensive and error-prone task, that does not scale well.

The work of Monsere et al. (2014), Lessons From The Green Lanes: Evaluating Protected Bike Lanes In The U.S., should be considered a pilot project in this effort, although the authors themselves do not describe it as such.

Monsere et al. aimed to address six questions:

  1. Do the facilities attract more cyclists?
  2. How well do the design features of the facilities work? In particular, do both the users of the protected bicycle facility and adjacent travel lanes understand the design intents of the facility, especially unique or experimental treatments at intersections?
  3. Do the protected lanes improve users’ perceptions of safety?
  4. What are the perceptions of nearby residents?
  5. How attractive are the protected lanes to different groups of people?
  6. Is the installation of the lanes associated with measureable increases in economic activity?

Apart from noting that, as with most sociological research, their survey response rates were dismally low (23-33% overall, counting even only partially completed surveys as full responses), to produce a socioeconomically skewed sample (e.g. the bicyclists being 89% white, 68% male, 82% having at least a four-year college degree, and 48% with annual incomes over $100,000)— this overview of their work considers only the first part of their question No. 2.

Monsere et al. installed video cameras along short bicycle sidepaths (“protected lanes”, “cycle tracks”) constructed between approximately the summer of 2012 and the early summer of 2013 as part of the Green Lanes Project. These were in four U.S. cities, San Francisco (two 0.3 mile paths), Portland (one 0.8 mile path), Chicago (0.8 and 1.2 mile paths) and Washington (a 1.12 mile path; no cameras were installed in Austin, although sociological surveys were conducted there). They did their video recording chiefly at intersections, six in these four cities in the summer and fall of 2013. This was then presumably while the users were still in a cautious or exploratory state, as they got used to the new facilities.

Only 12-18, or in one case 20, independent hours of video were analyzed from each intersection. As each intersection examined was given a unique treatment, results cannot easily be pooled. These are very small numbers.

(This makes for substantially less than 120 hours total. The authors seem to say they analyzed 144 hours of video at intersections. This would mean that some of this total came from multiple cameras examining the same intersection at the same time. The authors do show frame captures from some of their cameras. This observer would find it difficult to correctly identify the conflicts from the views on display.)

As noted following the opening platitude, any facility, no matter how poorly designed, will appear safe if examined over a short enough period of time.

The six facilities examined were all so new (less than or little more than a calendar year old) that there were no injury or death data available for them. (For comparison, the entire city and island of Montreal, with all its thousands of intersections, averages of late about five cyclist deaths and 25-50 police-recorded serious cycling injuries per year.) Thus, there would not have been a way to use even many more hours of recording to examine for any relationship between the surrogate outcomes (conflicts, violations or errant behaviours) and the outcomes of most interest, deaths and injuries.

Further, as this was neither a before-after study nor a comparison with standard intersections, there is no way to know whether the numbers of observed conflicts, violations, or errant behaviours, were themselves high or low.

As to the actual results from this pilot project, the much touted headline was that there were only six minor conflicts found, out of nearly 12,900 bicycle movements through intersections. The most basic problems with this headline are:

1. It is the wrong comparison. The conflict rate has to be the number of conflicts divided by the number of occasions where at least two users capable of conflicting are present, e.g. a bicycle and at least one other bicycle, pedestrian, or motor vehicle. Thus the authors give figures of 7574 turning motor vehicles, but only 1997 turning motor vehicles with bicycles present. The corresponding conflict rates (which they normalize by the products of bicycle and motor vehicle movements, not by the numbers of bicycle movements alone) they give for the individual intersections therefore vary by factors of approximately 3 to 10, depending on which figures are used.

2. Six is the total of observed “minor” conflicts, not the total number of observed conflicts. There were also 379 “precautionary” conflicts with motor vehicles, 216 with pedestrians, and 70 with other bicycles.

3. Besides conflicts, there were numerous violations or other errant behaviours: e.g. 9-70% of bicycles and 7-52% of turning motor vehicles in the various intersection designs used the lanes incorrectly, 1-18% of turning motor vehicles in the various mixing zone designs turned from the wrong lane, 5-10% of motorists turned illegally on red arrows at intersections with bicycle-specific signals, and 7-23% of bicyclists disobeyed their signals.

4. Without any theory or model of how any of these occurrences or their frequencies relate to death, injury, or property damage, and without any before-after or non-sidepath comparison data— not to mention, with the very small numbers of observation hours— there are almost no safety implications, positive or negative. The only concrete result is that one of the local authorities apparently deemed the problem of motor vehicles turning from the wrong lane (18%), straddling lanes (another 17%), or entering the turn lane early (15%) to be so severe that they later removed the intersection treatment and replaced it with another design (at Fell and Baker in San Francisco).

5. The sociological surveys tell another story: one-third of all bicyclists surveyed said they had been involved in at least one near collision on the paths, while 2% experienced an actual collision. 23% had a near collision with turning cars, 1.8% an actual collision with turning cars; 19% a near collision with a pedestrian, and 0.4% an actual collision with a pedestrian.

In short: this is an interesting pilot project, whose methods are impractical for the amount of data collection needed for meaningful safety results. Even with better methods, conflicts are only one facet of the bicycling, and overall safety picture; while road designers and road users, whether bicyclists or motorists, have to consider more than just safety. Convenience, transit time, cost, and greenhouse gas emissions also matter. A cycle track that, like the downtown de Maisonneuve track in Montreal, lies largely dormant in the winter, but delays motor vehicle traffic in the winter and ties it up spring, summer and fall, will be of no help in reducing CO2 emissions. The much touted headline results from this study are selective, overblown, and misleading. Any facility will appear safe if examined over a short enough period of time, and surely 12 to 20 hours each is short enough.