Tag Archives: Bicycling

A review of the film Bikes vs. Cars

I knew I’d have a problem with the film just based on the the title.

There can be animosity between people on bikes and in cars, but bikes and cars are machines, which have no feelings and generally don’t get into trouble unless there a person is behind the steering wheel or the handlebars. The title “Bikes vs. Cars” reminds me of a frequent complaint of bicyclists who have had incidents in traffic, “the car didn’t see me.”   The title and that statement both reflect a fear-based mental block which has led to the inability to conceive of the car as a machine under control of a human, with whom it is possible to interact, and so, much more often, to avoid incidents…

Enough. There’s more to say. My facebook friend Kelley Howell has posted a detailed review, which follows here:


Why I think the film, Bikes Vs. Cars, is a waste of money:

by Kelley Howell

It was a scattered, gawky film filled with untenable contradictions. Some thoughts:

The film switched back and forth between a desire to own the streets and use them as if they belonged to bicyclists who have a right to drive on them, free of cars, but then it dropped its pretense to militancy asking for small slivers of space on the edge, as if if that edge were some Magic Kingdom of safety. On one hand, the people in the film seem to be demanding a right to take the entire road and get the hated cars off it. On the other hand, it’s all about scampering out of the way, deferring to a dominant majority no one knows how to handle, let alone challenge.

As an example, there was a line in the film which went something like this: “At 1 AM, during the quiet of Carmeggedon in LA. I sneaked on to the 405 and rode my bike on this massive highway. It was beautiful. I owned that feat of human engineering. For the first time, I felt it was a marvel of human engineering that was made for me.”

Then they switch to Sao Paulo in Brazil, to capture the happy reactions of bicyclists who learned that the city is laying down 100s of kilometer of too narrow bike lanes in an very congested city where few people appear to follow traffic law to begin with. I was hard pressed to imagine all these scrappy motorists would respect the painted lines of a 4 foot wide gutter bike lane.

Which is it: do you want to drive a bike on that feat of human engineering, the 405, or a 4 foot bike lane with cars passing too close, driving out into your path, and right- and left-hooking you constantly? How is that demanding your rights? How is it safe? Accepting a scrap of asphalt, some of it carved out of a gutter built for sewer water? After all that rhetoric of wanting access to feats of human engineering, how is that you want to operate in a gutter bike lane?

The film trades in the imagery of the bicyclist, rolling free, free of motorists, free of the burden of a body on pavement, free because it can dodge the confines of hated “traffic”. The magic of the bicycle is its thrift, its speed, and its nimble ability to slip through crevices of urban congestion. It is at once traffic and the supposed escape from it.

But this is reminiscent of the propaganda that dominates the most pedestrian – har! – of auto advertisements where cars mean freedom, an open road, an endless horizon. This imagery in commercials is a stark counterpoint to the reality of miles of congested freeway, gridlock, and, well, to borrow a phrase, the hell that is other motorists at rush hour.

This trope — the bicycle as freedom, magically evading being captured in traffic — is present in an amusing fantasy entertained in the film: pulling 20% of all motorists off the Los Angeles roads and reinserting them with their derrieres planted in bike saddles. Apparently they will accomplish their 14.7 mile commute on their Dutchie or Cruiser, pedaling along at 10 mph?

Going by LA county numbers, 20% of the ~4.5 million motoring commuters is 900,000 bicyclists. Even if their commute where far shorter – say a manageable 5 miles at 10 mph — that’s a lot of bicyclists who get to share those four foot wide gutter bike lanes. Good luck with that!

Then, there was a main protagonist, name escapes, in Brazil. She says, to paraphrase, “What I want is some respect and for human cooperation.” And then the film plugs away about the lack of bike lanes. Having apparently conceded that motorists will NOT actually give bicyclists that respect or cooperatively share the roads, they ask for a sliver of space in the gutter.

Which is fine. Really. If that’s what you want. But don’t imagine segregating modes is about cooperating. It’s rather about demanding public resources be spent on gutter-based infrastructure in Brazil precisely because motorists WILL NOT share the road. No one has actually changed the domination of motorists. In this “victory,” existing configurations of power remain the same, leaving bicyclists just as powerless as they always were, only now they are marginalia set off by 6 inch stripes of paint.

The incident with the Dutch cab driver was high camp and deserves its own post. It was my impression that the cabbie staged the whole thing, a real drama queen pining for his 5 minutes on camera. Basically, it was exemplary of what Nietzsche called a transvaluation of values[1]: an opportunity for bicyclists everywhere to make the motorist suffer for a change.[2]

The problem is that this is an exercise in punishing schadenfreude. We are all supposed to love it that the roles have reversed in the Netherlands. The taxi driver has to be troubled, delayed, and dominated by the majority, bicyclists. We get to engage in gleeful enjoyment to see him upset, angry, cowed by the throngs of bicyclists blocking his every move. There! Take That, you bad, bad motorists. How do you think it FEELS to be marginalized like we were?

This is a stupid and shameful sentiment that shouldn’t be tolerated by anyone doing bicycling advocacy. But it is, unfortunately, celebrated by too many participation advocates – including this film, which trades in cheap theatrics and, well, quite frankly, trashy propaganda. At least have the decency to be sophisticated about it if you are going to trade in such infantilizing sentiments.

[1] I am unhappy with the choice of ‘transvaluation of values’ to express what I mean here. But it’s been a longass day. Tant pis!

[2] As for the transvaluation of values thing, for more detail on the problems with this position, see Wendy Brown’s work States of Injury: Power and Freedom in Late Modernity. Here, Brown captures the problem as one where, basically, an oppressed or marginalized group rises in power and status, promoting a compulsion to repetition rather than liberation:

“Initial figurations of freedom are inevitably reactionary in the sense of emerging in reaction to perceived injuries or constraints of a regime from within its own terms. . Ideals of freedom ordinarily emerge to vanquish their Imagined immediate enemies, but in this move they frequently recycle and reinstate rather than transform the terms of domination that generated them. Consider exploited workers who dream of a world in which work has been abolished, blacks who imagine a world without whites, feminists who conjure a world either without men or without sex, or teenagers who fantasize a world without parents. Such images of freedom perform mirror reversals of without transforming the organization of the activity through which the suffering is produced and without addressing the subject constitution that domination effects, that is, the constitution of the social categories, “workers,” “blacks,” “women,” or “teenagers.”

It would thus appear that it is freedom’s relationship to identity-its promise to address a social injury or marking that is itself constitutive of an identity that yields the paradox in which the first imaginings of freedom are always constrained by and potentially even require the very structure of oppression that freedom emerges to oppose.”

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.

Some thoughts about self-driving cars

Google’s report on its self-driving cars:


Most than half of the collisions reported in this document are slow-speed rear-enders of the Google cars. That’s unusual. It might be that the behavior of the Google cars is more cautious than what human drivers expect, so the Google cars stop more often abruptly or at unusual places, and so are not tailgater-friendly. I’d suggest that the Google cars might be equipped with a rear-facing warning device.

It seems to me that self-driving cars will be able to avoid any collision where a human driver could avoid fault, and others. In other words, operators of non-automated vehicles (including bicycles) and pedestrians who follow the conventional rules of the road will be able to operate safely around automated vehicles. Vehicles with automated crash avoidance (not necessarily completely automated vehicles, even) will not rear-end bicycles, and so the premise of fear from the rear evaporates if automated crash avoidance becomes universal with motor vehicles. Self-driving cars will not be able to avoid collisions where avoidance would require violating the laws of physics. Vehicles with automated crash avoidance will be able to avoid some collisions in which the potential colliding vehicle or pedestrian is outside the field of view of a human driver, such as right-hook collisions, as long as there is a clear sight line to the automated vehicle’s sensor. Same for a large truck’s high hood which prevents the driver from seeing a pedestrian crossing in front.

Automated vehicles will not be able to avoid left-cross collisions where the bicyclist or motorist is passing on the right of other vehicles and concealed by them, or pedestrian dart-out collisions. The concept of fully networked vehicles is supposed to address this problem. All vehicles approaching the same place in the road network are envisioned as communicating with each other even when they are hidden from each other’s view. As someone with an electrical engineering degree, I consider this at best a very difficult proposition, and it might be described as a pipe dream. Bandwidth, interference and reliability issues lead me to ask “what could possibly go wrong?” Also, instrumenting every object on the road is only practical on a limited-access highway — no, not even there, because there will still be breakdowns, wild animals, debris. On other roads, is every pedestrian going to carry a transponder? I don’t think so.

Automated crash avoidance is easily hacked by rolling a trash can out into the roadway, and the like. The caution which automated crash avoidance inherently incorporates changes the dynamic from the one among humans, which can involve a game of bluff. To me, this means that automated vehicles will be extra-cautious in the presence of other drivers and pedestrians who do play the game of bluff, and so the progress of automated vehicles will be slow and erratic in, for example, Boston traffic.

All this leads to the question: does behavior change as these vehicles become more common? Does infrastructure change? Every new technology takes a while to find its feet. As Marshall McLuhan said, “We look at the present through a rear-view mirror. We march backwards into the future.” Do conditions become better or worse for bicyclists and pedestrians? And why? We have some control over this depending on the direction which is set for the technology, but also, time will tell.

Another serious issue I’ve heard mentioned is the car which is not only driverless but passengerless. There is potential for an increase in traffic if a car can be called to meet a person (like a passengerless taxi), or directed to drive around and around the block empty when a parking space can’t be found. I can’t say how serious this problem will be. To some extent, that depends on the extent of freedom afforded to people’s control over the driverless cars. It’s an interesting legal question involving private use of public space. We already face this question with congestion-pricing schemes. But on the other hand, fewer cars on the road might be needed, because the car-sharing model works better when a car can be called rather than only stationed. Again, time will tell.

Change lanes in a roundabout?

Ohio cyclist Patricia Kovacs posted an e-mail asking some questions about roundabouts:

Ohio engineers are telling us to use the inner lane for left turns and U turns. Both the FHWA [Federal Highway Administration] and videos available on our local MPO [metropolitan planning organization] website say this. I shared this when we asked for updates to Ohio Street Smarts. If the FHWA and MORPC [Mid-Ohio Regional Planning Commission] are wrong, then we need to fix it.

Would you review the 8 minute video on the MORPC website and let me know what I should do? If it’s wrong, I need to ask them to update it. This video was made in Washington and Ohio reused it.

Looking further into the problem, I see a related practical issue with two-lane roundabouts, that the distance between an entrance and the next exit may be inadequate for a lane change. The larger the roundabout, the longer the distance in which to change lanes, but also the higher the speed which vehicles can maintain and so, the longer distance required. I’m not sure how this all works out as a practical matter. Certainly, turning right from the left-hand lane when through traffic is permitted in the right-hand lane is incorrect under the UVC [Uniform Vehicle Code], and results in an obvious conflict and collision potential, but I can also envision a conflict where a driver entering the roundabout does not expect a driver approaching in the inside lane of the roundabout to be merging into the outside lane.

All in all, the safety record of roundabouts is reported as good (though not as good for bicyclists and pedestrians), but I’m wondering to what extent the issues have been subjected to analysis and research. When I look online, I see a lot of roundabout *promotion* as opposed to roundabout *study*. Perhaps we might take off our UVC hats, put on our NCUTCD [National Committee on Uniform Traffic-Control devices] hats, and propose research?

Thanks, Patricia.

This post was getting long, so I’ve placed detailed comments on the Ohio video, and embedded the video, in another post. I’m also working on an additional post giving more examples, and I’ll announce it here when it is ready.

Here are some stills from the video showing the conflict between through traffic in the outer lane and exiting traffic in the inner lane.

First, the path for through traffic:

Path for through traffic in a roundabout

Path for through traffic in a roundabout

Next, the path for left-turning traffic:

Path for left-turning traffic in a roundabout

Path for left-turning traffic in a roundabout

Now, let’s give that picture a half-turn so the left-turning traffic is entering from the top and exiting from the right:

traffic in a roundabout, image rotated 180 degrees

Path for left-turning traffic in a roundabout, image rotated 180 degrees

And combining the two images, here is what we get:

Conflict between through traffic and exiting left-turn traffic

Conflict between through traffic and exiting left-turn traffic

The image below is from the Manual on Uniform Traffic Control Devices, and shows similar but not identical lane use. The arrows in the entry roadways direct through traffic to use either lane.

FHWA diagram of a roundabout with lane-use arrows.

FHWA diagram of a roundabout with lane-use arrows.

Drivers are supposed to use their turn signals to indicate that they are to exit from the inner lane — but drivers often forget to use their signals. Safe practice for a driver entering a roundabout, then, is to wait until no traffic is approaching in either lane, even if only entering the outer lane.

A fundamental conceptual issue here is whether the roundabout is to be regarded as a single intersection, or as a series of T intersections wrapped into a circle. To my way of thinking, any circular intersection functions as a series of T intersections, though it functions as a single intersection in relation to the streets which connect to it. Changing lanes inside an intersection is generally prohibited under the traffic law, and so, if a roundabout is regarded as a single intersection, we get the conflicts I’ve described.

Sometimes, dashed lines are used to indicate paths in an intersection, when vehicles coming from a different direction may cross the dashed lines after yielding right of way or on a different signal phase. More commonly, a dashed line  indicates that a driver may change lanes starting from either side. The dashed lines in a two-lane roundabout look as though they serve the second of these purposes, though they in fact serve the first. These are shorter dashed lines than generally are used to indicate that lane changes are legal, but most drivers don’t understand the difference.

That leads to confusion. If you think of the roundabout as a single intersection, changing from the inside to the outside lane is illegal anywhere. If you think of the roundabout as a series of T intersections, changing lanes should occur between the entries and exits, not opposite them –though there is also the problem which Patricia mentioned, that a small two-lane roundabout may not have much length between an entry roadway and the next exit roadway to allow for a lane change. That is, however, much less of a problem for bicyclists than for operators of wider and longer vehicles. It would be hard to construct a two-lane roundabout small enough to prevent bicyclists from changing lanes.

My practice when cycling in conventional two-lane traffic circles — and there are many in the Boston, Massachusetts area where I live — is to

  • enter from the lane which best leads to my position on the circular roadway — either the right or left lane of a two-lane entry;
  • stay in the outer lane if leaving at the first exit;
  • control the inner lane if continuing past the first exit;
  • change back to the left tire track in the outer lane to prepare to exit.

That way, I avoid conflict with entering and exiting traffic in the outer lane, and I am making my lane change to the right in the slow traffic of the circular roadway rather than on the straightaway following it. This is what I have found to make my interactions with motorists work most smoothly. Why should a bicyclist’s conduct in a roundabout be different?

It is usual to be able to turn right into the rightmost lane of a multi-lane rodway while raffic is approaching in the next lane. I don’t know of any other examples in road design or traffic law in the USA where a motor vehicle is supposed to turn right across the lane where another motor vehicle is entering it. Bike lanes are sometimes brought up to intersections, though the laws of every state except Oregon require motorists to merge into the bike lane before turning. The illustration below, from Dan Gutierrez, depicts the problem.

Right hook conflicts, from Dan Gutierrez's Understanding Bicycle Transportation

Right hook conflicts, from Dan Gutierrez’s Understanding Bicycle Transportation video and course.

Applicable sections or the Uniform Vehicle Code are:

  • 11:304 (b) — passing on the right is permitted only when the movement can be made in safety.
  • 11:308 (c) — a vehicle shall be driven only to the right of a rotary traffic island.
  • 11:309 (a) — no changing lanes unless it can be done in safety
  • 11:309 (d) — official traffic control devices may prohibit lane changes
  • 11:601 (a) Right turns – Both the approach for a right turn and a right turn shall be made as close as practicable to the right-hand curb or edge of the roadway.


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.

When slow is too fast

The basic speed limit, not to go too fast under the existing conditions, is often lower than the posted speed limit.

When facilities like the bike lane in the video are built in which 10 mph, or even 5 mph, is excessive speed, and, worse, when we are required by law to use them, then we get clobbered three ways. If we ride at safe speeds, the utility of bicycling for transportation and exercise is greatly reduced. If we ride faster than is safe, then we may crash, and be held at fault. If we avoid the facilities, we may be cited for not staying in our place, and harassed. And this, when bicyclists rarely can ride at the posted speed limit.

I’ll also quote my friend Mighk Wilson’s comments about the video:

It’s important to differentiate between “fault,” which is a legal matter for our purposes here, and “contributing causes.” If we only address fault we will usually fail to prevent crashes…

So who contributed to your crash? Obviously the motorist…he’s 100% legally at fault. But the designer of the bike lane also contributed, by leading you into blind spots where you’d be in conflict with turning vehicles. You yourself contributed by traveling at a speed at which you were unable to see, react and brake for the turning vehicle. Our bicycle advocacy groups contributed by insisting that bicyclists should always get to pass stopped motor traffic even when it’s risky to do so. Our land use planners contributed by allowing commercial driveways so close to major intersections. I could go on…

Part of the problem here is not only that the bike lane leads to blind conflicts, as Mighk points out, but also that it leads to false expectations of what is safe. I’d also add that planners, and lots of other people, contributed to causation of the crash by generating patterns of land use and mode choice which lead to traffic congestion. It is ironic that while it was only safe to travel at low speed in the bike lane, the traffic in the travel lane was stop-and-go, and had stopped completely. Whether a cyclist would have been able to travel safely at a higher average speed without a bike lane is open to question.

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.

Fixie or track bicycle?

Track racing bicycle,from Bicycling Magazine

Track racing bicycle, from Bicycling Magazine. The caption in the picture reads “On a fixie, there are no gears or brakes. Only your legs control the drivetrain.”

From Bicycling Magazine, June 2014, page 28:

“A fixie (or fixed gear) is a singlespeed without brakes and without the mechanism that allows the bike to coast when you’re not pedaling.”

That is a description of a track racing bicycle, which is only one kind of bicycle with a fixed gear. The caption in the picture with the article repeats this description.

Let’s get definitions straight:

  • A fixed gear is a connection between the pedals and the driving wheel without a mechanism which allows coasting.
  • Antique high-wheeler bicycles have a fixed gear;
  • Children’s tricycles have a fixed gear;
  • Sturmey-Archer sells a three-speed fixed-gear hub, and so, some fixed-gear bicycles are not singlespeeds;
  • “Fixie” is not synonymous with “fixed gear”. Rather, “fixie” is slang for a bicycle with a fixed gear.
  • Fixed-gear bicycles for the road,  as a matter of common sense, safety and traffic law in many jurisdictions, must have a brake.

Though it is possible to slow a brakeless fixie by resisting the rotation of the pedals, this braking is not as effective as with a front handbrake, and can be lost due to the cranks’ outrunning the feet, or the chain’s coming off.

The photo with the Bicycling Magazine article shows a brakeless fixie on a street — illegal in many places, and with impaired safety due to the longer stopping distance and unreliability of braking. Also, the cyclist is using toe clips and tightly-adjusted straps with the end of each strap passed through the slot at the bottom of the buckle. The straps cannot, then, be adjusted while riding — OK on the track where a starter holds the bicycle upright, but not on the road. I have to wonder whether the cyclist in the photo was assisted in starting, or is being held upright for the photo by someone outside the picture.

Why am I taking the trouble to write this? Primarily, because the Bicycling Magazine article may induce people to take up riding fixed-gear bicycles without brakes on the road, and fumble with toeclips and straps, and crash, and be held at fault for crashing for lack of a brake. I am distressed that editors at Bicycling Magazine would pass on an incorrect description which generates confusion and might promote such behavior.

A thorough and accurate discussion of fixed-gear bicycles for use on the road may be found in Sheldon Brown’s article.

For the record, I own a fixie, shown in the photo below, and it is street-legal, equipped with dual handbrakes. If I had only one brake on this bicycle, it would be the front brake — but for riding with a freewheel, or on steep descents, I have installed a rear brake as well.

John Allen's fixie

John Allen’s fixie

Godzilla’s toothpaste decorates Seattle bikeway

A new bikeway has recently opened on Broadway in Seattle, Washington state, USA.

Someone has posted a video of a ride on the newly-opened bikeway.

(To get a better view of the video, click on “YouTube” and open it up full-screen.)

This is an uphill ride, very slow in most places. Traffic was light on the street, and even lighter on the bikeway. It will be interesting to see how the situation develops when traffic is heavier.

The bicyclist who made the video is clearly aware of the hazards, as he or she repeatedly checks for turning traffic before crossing intersections. Others might be more naive.

What most catches the eye though about this installation is the “Godzilla’s Toothpaste” barriers between the bikeway and parking spaces — an artistic touch, to be sure, though also a collision hazard, and sure to be pummeled by cars pulling into parking spaces. The toothpaste is visible a few seconds from the start of the video and also later.

As described by Seattle cyclist Joshua Putnam, the installation of the bikeway followed from a series of events, like a chain of dominoes falling over, except that some the dominoes were bicyclists. The first of these events was installation of a light rail line in the street. Then, bicycle crashes became much more frequent.

Light rail lines in streets are a serious hazard for bicyclists, from wheels’ getting caught in the flangeway, and from bicyclists’ having to choose their line of travel to avoid that risk. The problem is worsened by the tracks’ curving over to the edge of the street at stops — necessary so there can be a raised platform and wheelchair access.

To address the hazard it created with the trolley tracks, Seattle installed a two-way, one-side-of-the-street bikeway, on this two-way street. Such bikeways pose problems anywhere, due to the increased number of conflicts and unusual movements at intersections — but also much of Broadway is steep, and bicyclists traveling opposite the usual flow of traffic on the bikeway are going downhill. Crossing an intersection or driveway from right to left on the near side has been well-established as highly hazardous.

Before the trolley tracks, before the bikeway, bicyclists could travel downhill as fast as the motor traffic. Now, the safe speed is hardly more than walking speed, and with repeated checks for crossing and turning conflicts. As is the usual practice, large swatches of green paint have been spread on the street to demarcate zones where bicyclists and motorists operating according to their usual expectations are concealed from each other until too late to avoid collisions.

Motorcyclists also are at risk from the trolley tracks, but they are excluded by law from the bikeway.

Children’s abilities — focusing on peripheral vision

My previous post addressed children’s cycling abilities. I’d like to take the discussion a bit further here.

A conventional statement about children’s cycling abilities, as expressed on an e-mail list, is:

Children also have less than fully developed peripheral vision and are very poor judges of the speed of automobiles.

Pioneering cycling educator John Forester replied:

Presumably, it depends on the age of the child. Many of us have known children aged seven, who have grown up in cycling families, who cycle in accordance with the rules of the road for drivers of vehicles. The ability is there; it just has to be trained. I have taught classes of eight-year-olds who learned to cycle properly in the traffic of two-lane streets in residential areas. I fail to see much point in the peripheral vision worry, because all cyclists have to learn to look at whatever is going to be important; what’s out at the side has little relevance. As for judging the speed and distance (you need to know both) of other traffic, say automobiles, any person has to learn to judge whether or not there is time to make a movement or it will be necessary to wait. I’ve watched the judging skills of eight-year-olds improve as they practice various traffic movements. In my opinion, the people who express the concerns about such mental matters have not had experience in training cyclists; they just measure (or try to measure, or make assumptions based on irrelevant measurements, or …) children without any knowledge of what is actually required for cycling in traffic, and are therefore completely ignorant of how to learn the skills.

I wouldn’t have been as harsh as Forester, but I agree that reliance on data from research into mental or perceptual abilities, without actually measuring cycling performance, misses the mark. Abilities do appear sequentially, as shown for example in this paper. There are studies which show that the acquisition of skills in childhood can be advanced by a couple of years through training. The minimum age to obtain a driver’s license reflects a societal judgment of the maturity necessary to drive safely.

I think, however, that the claim that children of elementary-school age have limited peripheral vision is commonly misstated and misinterpreted. It isn’t that the range of angles of peripheral vision increases — as if a child’s retinas have only a small patch of sensory receptors at the center — “tunnel vision” — which expands over the years. I say this from my own experience.

What is importantly less developed in children is the conscious awareness of the peripheral visual field. It sends too much and too complicated information for the immature or untrained brain to process fully.

I recall a peripheral-vision experiment at school when I was 8 or 9 years old, checking how far to the side I could place my hand before I could no longer perceive the wiggling of my fingers. The angle was the same approximately 90 degrees as it still is 60 years later — except that I could perceive the wiggle but not yet the shape of the hand. From age 3, I rode a tricycle, from age 7, I rode a bicycle and from age 17 I drove a car, and did not fail to notice hazards in the peripheral visual field. Peripheral vision short of full, conscious perception, and like the spatial sense of hearing, serves to draw attention, so the eyes and head turn to focus central vision.

I learned to perceive my peripheral visual field consciously in my twenties. I trained myself by focusing my attention on objects in the peripheral field instead of turning my eyes to look at them. This can look weird in social situations! I undertook most of my training while riding my bicycle. Over a period of a couple of years, I got to where I am as conscious of my peripheral field as my central field, except that the peripheral field is blurrier. I see the entire panorama in front of me at once.

Moreover, the rod cells, sensitive enough even to form an image under starlight, are only in the peripheral visual field. The fovea, at the center of the visual field, has only the color-discerning and sharp-imaging cone cells, which are far less sensitive,. In very dim light, the center of the visual field becomes a blind spot and, to fill it in, the eyes must dart around like those of a person born without cone cells — as described in Dr. Oliver Sacks’s book The Island of the Colorblind. Walking outdoors on a starlit night in an area with dark sky offers a good lesson about visual abilities.