Category Archives: Bicycling

Tesla Thermal Troubles: the Li-ion in Winter

My friend Brad Meyer, who lives in the next town over from me in Massachusetts, has owned a Tesla Model S car for more than a year. His observations raise some serious questions about the advantages of an electric car, particularly in winter — and about the pricing of electricity in Massachusetts.

Electric power generation is most efficient if power demand remains nearly constant; off-peak pricing can work well both for the power company and customers, by shifting time-insensitive tasks such as doing laundry and charging electric-car batteries into hours when electricity demand is otherwise low. California, where the Tesla is made, has an advantageous off-peak pricing scheme for electricity. Massachusetts has only a weak version of such a scheme. There are also serious cold-weather performance issues with the Tesla due to the slowing of the chemical reaction in its lithium-ion battery. Brad kept track of his car’s electricity use, and writes:

The Tesla’s info-center miles-remaining is based on an average of 293 watt-hours per mile. My measurement was from a winter period, and was calculated from a measurement of average watt-hours/mile over several winter months. My winter average was about 425. These numbers are not immediately available to me so I’m trying to remember them; they’re approximately correct.

Most of the time, I kept the car in a garage that is heated to about 38 degrees Fahrenheit in the winter, but there were times when, as an experiment, I left it out when the morning reading was about +5 F. When the car is turned on in those conditions, it begins to heat both the cabin and the batteries. There is very limited forward power available and regenerative braking is totally disabled, so you get no energy return at all to the batteries from slowing down and no braking effect except what you supply with the pedal for the first couple of miles.

I applied for a time-dependent electricity rate and saw that one part of the bill went from about 7.8 cents all the time to 3.9 at night and 9.6 during the day. But wait! That’s just the transmission charge. The generation charge, which should clearly change during the night when the machinery is just ticking along, is 15.9 cents all the time. This is the big fast one that we get from our power company (Eversource). So I’m charging my car at 19.8 cents per kilowatt-hour and I’m using 425 watt-hours/mile, which costs me 425 x 19.8/1000 = 8.4 cents per mile. You can run a Toyota Corolla for about that much in gasoline, or maybe a bit less.

The summer consumption of about 315 watt-hours per/mile gives an electricity expense of around 6.2 cents a mile, which is better than most gasoline-engine cars but not dramatically so.

Don’t believe anyone who tells you he drives a Tesla for environmental reasons. That’s not what the car is about.

What is the Tesla about, then? As Brad demonstrated to me, it has astonishing acceleration, and so it counts as the first mass-production electric car with an appeal to car buffs. (Brad is one.) The acceleration is very strong at low speeds, unlike with an internal-combustion engine, which produces the most power near the high end of its rpm range. Brad tells me, though, that the Tesla’s power drops off with sustained acceleration, as protection cuts in to prevent the motors from overheating. And then there are the winter problems.

What might be done to improve the winter performance? Consider that a gasoline engine burns fuel on the spot to generate power, but only about 1/4 of the energy in the fuel is converted into mechanical energy to move the car. The other 3/4 becomes waste heat. About half of that is carried away in the exhaust, but the other half which the coolant carries away is ample to heat the passenger compartment. Though a fossil-fuel-burning or nuclear power plant is generally more efficient than a gasoline engine in a car, the waste heat is lost at the power plant. The electric car’s heater steals battery capacity, reducing the car’s range on a charge and increasing the cost per mile.

Electricity generation using hydro-, wind or solar power avoids the pollution, health, safety and environmental issues with fossil-fuel and nuclear power plants, but does not reduce the power demand to heat an electric car, or make the car run better in winter.

I’d think that it would make sense for an electric car to have the battery  well-insulated against cold, and with a small electric heater. So, in the best-case scenario with today’s battery technology, an electric car could start up smartly if it had been charging, but would need a warm-up period if it had not been. The battery heater could keep the battery warm while the car is charging overnight, or be activated remotely or on a timer if the car is parked where it can’t be charged.  Warming the battery  in advance would avoid experiences Brad’s when leaving an underground parking garage after attending a concert one evening: the car would slowly advance one foot up the exit ramp, then stop to gather its forces, then one more foot…

One advantage of an electric car, especially if the battery is already warm, is that the heater for the passenger compartment can be turned on immediately — or even in advance without starting the motor — rather than with a delay as with the heater in an internal-combustion-powered car.

The battery also needs to be actively cooled during use: lithium-ion batteries can overheat. The Tesla’s battery is liquid-cooled, and there is a battery heater, but evidently it lacks smart controls.

It is likely that technology will improve, but for now, the Tesla unfortunately cannot match the start-up-and go winter performance of a vehicle with an internal-combustion engine.  Economy and range also suffer in cold weather. The same is likely true of other all-electric vehicles.

There are other Web pages discussing cold-weather performance of electric cars — search on <electric car battery winter>to find them. One specifically about the Tesla is here.

Streetsblog’s Angie Schmitt seeks to purge engineers

I just ran across a post from March 2015 by Angie Schmitt for Streetblog:

The title is “Engineering Establishment Sets Out to Purge Deviant Bikeway Designs”

I quote:

The NCUTCD consists mostly of older engineers from state DOTs. In recent years, its bikeway design orthodoxy has been challenged by a new wave of engineers looking to implement treatments that the American street design establishment has frowned upon, despite a proven track record improving the safety and comfort of bicycling. Most notably, the National Association of City Transportation Officials has released guidance on the design of protected bike lanes that the MUTCD lacks.

NACTO’s guidance is gaining adherents. Dozens of cities have implemented protected bike lanes in the past few years. The Federal Highway Administration endorsed the guide in 2013.

The NACTO Guide is formatted to appear to be an actual design guide to a lay person, but does not serve as one for an engineer who is faced with the actual task of designing anything. That is one of the problems which the NCUTCD task force is attempting to address. The NACTO Guide has stirred up a lot of interest among the general public, politicians and advocates of increased bicycle use, but it does not offer a decision tree, or  specifications, or safety cautions sufficient to guide the design of safe and practical bikeways. I’ve addressed that here.

As to the “proven track record,” search on “Lusk” in this blog for some reviews of studies which purport to overturn the results of decades of research showing an increase in crash risks at driveways and cross streets with sidewalk or sidewalk-like routing of bicycles, and an overall increase in crashes due to this “protection.”

Schmitt’s use of the terms  “purge” and “deviant” — to describe the deliberations of an engineering task force — play on the image of totalitarian states’ placing people who reject party line before a firing squad, and speaks for itself.



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.”

The Downtube bike

On the weekend of November 7 and 8, 2015, I traveled to Pennsylvania and attended the Philadelphia Bicycle Exposition. My host John Schubert lent me his Downtube folding bicycle. I used it to explore the city and shoot video of bicycling conditions.

As I returned to the expo, Mark Casasanto, of Imperial Security, asked me whether I’d pose with three nattily-attired young women, members of his security team. Well, why not!? So I did, with the Downtube bicycle. Here’s Mark’s photo.

John Allen with members of the security team

John Allen with members of the Philly Bike Expo security team. Photo by Mark Casasanto.

Russian Immigrant Yan Lyansky sources and imports Downtube bicycles. He promotes them on the Internet, and sells them by mail order out of a warehouse, avoiding middleman expenses.

It is often easiest for an outsider to see the big picture in new surroundings. Having lived under the thumb of Soviet Communism, many Russian immigrants, in my experience, are wide-eyed to the opportunities offered by the free enterprise system.

(This specific bicycle is an older model, no longer available. The company has newer models — described on its Web site)…

At $269, even in 2006, this bicycle was a bargain. That the Downtube is a folding bicycle makes it easier to ship, and no customer assembly is needed. Even the pedals come pre-installed — folding pedals.

The Internet business model, now being increasingly adopted by mainstream bicycle brands, is a serious headache for brick-and-mortar bicycle shops — which can sell a bicycle but also customize, maintain and repair it. In case you didn’t know, their numbers are in decline.

But on the other hand, the Downtube is by no means a “bicycle-shaped object” — cheaply made and poorly assembled, as commonly sold at big-box retailers, the other bane of the brick-and-mortar segment.  The DownTube is a somewhat clunky but serviceable folder. The frame is stiff: the bike rides a lot like my old (also clunky but serviceable) customized Raleigh Twenty. Mechanically, everything about the Downtube works OK. The hinges have a clever safety feature in case someone forgets to tighten the quick releases. The derailleur gearing works fine, but I hear that the Sturmey-Archer 8-speed internal-gear hub on some Downtube bikes was a real headache, too many returns under warranty. Too bad about that: I like IG hubs better for city bikes.

I did find a couple of corners cut in components and assembly.

  • While the wheels were true, and had good aluminum rims, the spokes are cheap, galvanized, noticeably corroded in the ten years since this bicycle was new. Galvanized spokes on some of my bikes have lasted 30 years or more, but corrosion could be a problem for someone who keeps the bike near salt water.
  • The rims have recessed spoke holes, but the rim strips were not fabric, but rubber which the inner tube can punch through and go flat — also too wide to fit in the well of the rim, keeping he tires from seating properly. I replaced the rim strips with glass fiber strapping tape, which John had available. That works, though I like ductape better for this use. In either case three or four layers should be applied.
  • Over-wide rubber rim strip

    Over-wide rubber rim strip

    Bearings in one hub were overtightened. This problem really needs attention as it can lead to early failure. This is the kind of thing which a pre-sale checkover in a bike shop can set right.  (Though sad to say, that doesn’t always happen either!)

A couple of specifications also weren’t to my preference:

  • The rear  fender could extend farther back. The tire can still throw water up at the cyclist.
  • The handlebars are unnecessarily long. The extra leverage of long handlebars is really only necessary for technical off-road riding and is hazardous in tight situations.  Catching a handlebar end on a post, the side of a vehicle etc. turns the front wheel to one side and results in a hard fall.

But all in all, as I said, the Downtube is a serviceable bicycle and the price was right.

John Schubert obtained this bicycle in the first place to write a review for Adventure Cyclist magazine, going into more detail on both technical specifications and the business model. Lyansky refused to take the bicycle back, and it has seen various uses, by several people, over the years. John rides it in the videos from our 2009 New York City field trip.

When I sent John my comments about the bike in an e-mail, he replied: “to me, its biggest shortcoming is that it is still pretty large when folded.  I also dislike the suspension fork.  I prefer rigid forks.  If I were to use a folding bike regularly, I’d buy something that folded more compactly.  But a folding bike just isn’t part of my current lifestyle.”

Well, a folding bike is part of my lifestyle, the bike-business issues are interesting, and so, you have this blog post! The suspension fork also helped to reduce shake in my videos.

Reflective Clothing as Panacea — again.


Photo from NYT article

Photo from NYT article

This photo in a New York Times article shows a bicyclist riding with a reflectorized shirt, which shows up well in a photo taken with flash on the camera, but the bicyclist has NO HEADLIGHT.

The manufacturer of the shirt wouldn’t want to distract people from promotion of this (gasp) cool and different product which might just possibly Save Your Life, by decking the bicycle out with legally-required nighttime conspicuity equipment which would alert the pedestrian stepping off the curb, or the motorist backing out of a driveway.

Nor would the vaunted journalists at the Newspaper of Record bother to inform themselves that they are complicit in a potentially deadly conspicuity shell game.

Unfortunately our government has no effective way to slap down such promotions. At least two previous, very similar promotions of reflectorized fabric have occurred in the USA.

The article also includes an uncritical review of other reflectorized items, and of the Hovding inflatable bicycle helmet, which has failed US safety standards and which obviously will not work for collisions with overhead objects (tree branches and the like), as it depends on abrupt motion of the cyclist to trigger inflation.

As I wrote this, I had just returned home from a meeting on my bicycle, well after dark. Equipment: Bright Dosun LED headlight with shaped beam pattern; Union generator taillamp, but battery-powered with 2.4 watt bulb instead of the standard 0.6 watt bulb; 3″ diameter amber SAE automotive rear reflector; reflective material on the back of my Shimano SPD sandals; yellow non-reflective T-shirt and olive-green shorts; helmet without reflective material, not that I think additional reflective material is a bad idea as a supplement. Also, I obeyed the traffic law, used assertive lane positioning when appropriate, and a helmet-mounted rear-view mirror, which helps me time my merges into the travel lane. And here I am, safe and sound and grumpy as usual!

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,

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.

Ogden, Utah skateboarder stop

There’s plenty of confusion to go around here.

Deputy: “I don’t care, you’re right in the middle of the road.” No, the boarder was on the shoulder, at least in the part of the video the TV station broadcast.

Was that legal? Bicycling is allowed on shoulders in many states. I couldn’t find anything on that on the Utah legislative site section on bicycles,

But the man was on a skateboard, not a bicycle. Under Utah law, the skateboard is defined as a vehicle, last definition here: and so, under the law, the skateboarder should have been in the travel lane, not on the shoulder or a sidewalk, if any, as little sense as that may make.

So, the officer’s charge was false. If the boarder were defined as a pedestrian, then shoulder use in the absence of a sidewalk would be legal if the boarder was traveling opposite the direction of traffic (he wasn’t), — not that this is sensible when it would have required crossing to the far side of a multi-lane road.…/Title41/Chapter6A/41-6a-S1009.html.

There is a sidewalk, as shown in Google Earth and Street View images.

The TV station video is edited at 00:25. It doesn’t show the entire conversation between the deputy and the boarder before the boarder attempted to flee — so we don’t know about an opportunity to comply. Other question is how the boarder could comply if there was nowhere to go except up and down a road bordered by vegetation. The deputy ran after the boarder and attempted to stop him. Probably better to let him go. The boarder fought the deputy, violently. Not smart at all.

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.


Comments on the Ohio roundabout video

I’ve moved the comments here from another post, which was getting long.

Here’s the Ohio video:

Summarizing my comments about the video, it shows roundabouts, a useful, time-efficient though space-intensive intersection design, but it gives some questionable advice on design and on how to use roundabouts. There are safety issues, and also legal implications are unclear, due to a contradiction of normal rules of the road.

  • While good advice for pedestrians is given, the video includes an overhead view of a roundabout in a residential area with a crosswalk at only one of the three legs of the intersection.
  • The advice for bicyclists to walk in the crosswalks is a surrogate for good design of crosswalks (or crossbikes) so bicyclists can safely ride through them, also reducing delay to both bicyclists and to traffic on the roadway.
  • In the video, a bicyclist is shown properly centered in the right lane to exit a roundabout, but just before that he is riding adjacent to a truck, contrary to advice also given in the video. He was in danger of being left-hooked at the previous exit.
  • Contrary to normal rules of the road, the video shows and advises that some drivers exit the roundabout from the inner lane, while other vehicles travel through in the right lane. Through-traveling drivers are expected to yield to the ones left-hooking them. What traffic law actually applies is unclear. If there is a special rule for roundabouts, it violates the usual rule and also violates the principle of destination positioning. Bicyclists usually would rather be in the right lane when exiting,

More-detailed comments about the video are below. The URL at the start of each comment links to the location in the video which relates to the comment. I’ve published the same comments on the YouTube page with the video.

0:50 Overhead view shown briefly shows the inner lane leading to a 4-lane exit. However, if you look closely, there are nonetheless dashed lines between the lanes and through arrows in the outer lane, — so the markings do not indicate that all traffic coming from previous entrances must use the inside lane. The markings maximize capacity by allowing exiting from either lane, regardless of where entering — though there is then a conflict between traffic passing an exit in the right lane and exiting from the left lane. My best advice for bicyclists who are riding through the roundabout is to ride centered in the outer lane while approaching the exit to avoid an unnecessary merge and avoid being right-hooked by exiting traffic or left-hooking through traffic, while also being in clearer view of entering traffic than if riding around the outside. Also, the drawing does not address all bicycling and walking movements. There is one cyclist shown in the illustration, riding with the direction of traffic on the sidewalk directly above the roundabout in the image, and that’s OK, but there are no ramps to and from the roadway to the sidewalk; on the other side of the intersection, there is no sidewalk; and there are no crosswalks across two of the three legs of the intersection, in a residential area.

1:00 Police officer narrating indicates that roundabouts “make our communities safer not only for motorists, but for pedestrians as well.” This contradicts the example in the overhead view, which lacks a full complement of sidewalks and crosswalks, and he also does not mention bicyclists.

2:00 Yield principle is good. Yielding is a fundamental principle of traffic operation which is not widely-enough understood. 2:10 vehicles are shown exiting the roundabout in the right-hand lane of a four-lane roadway, and that’s OK.

2:50 “The lane allows left turn, straight-ahead movements and U turns only,” with the unstated implication that drivers must remain in the left lane while exiting.

2:55 “Allowable right-lane movements include right turns or straight-ahead movements.” The two previous statements together establish a left-hook conflict between straight-ahead movements in the right lane and right turns from the left lane.

3:12 Animation at shows a vehicle exiting from the left lane, crossing the right lane in which through movements are permitted.

3:34 “When driving in the left lane, always maintain your lane position until you exit” — left-hook conflict.

3:40 A vehicle making a straight-ahead movement yields to traffic in both lanes when entering. The entering driver may not know whether the driver coming from the left intends to exit (conflict!) or not (no conflict!). The exiting driver is turning right from the left lane, in violation of the principle of destination positioning.

4:15 “The driver in the right lane cuts off the driver in the left lane intending to exit.” This is exactly the same as saying “The driver in the right lane traveling straight through cuts of the driver in the left lane intending to turn right.” The vehicle in the left lane is behind the one in the right lane and not in a position where the leading driver would normally have to look when continuing on a roadway. Both the movements shown — going straight through in the right lane and turning right from the left lane — are permitted movements, according to the animation shown previously — but turning right across a travel lane without yielding is a violation everywhere except, as describe here, in a roundabout.

4:30 “Never change lanes inside the roundabout.” Troubling advice, and especially for bicyclists — not only results in hook conflicts, but also results in unnecessary delay.

4:45 “U Turns are only allowed in the left lane” – Good enough except for the issue with hook conflicts at the exit.

5:15 “If you follow a truck into a roundabout, do not attempt to pass.” Good advice anywhere it would be necessary to share a lane with a large truck to pass it.

5:26 “When emergency vehicles approach, always give them the right of way.” More generic good advice.

6:03 “Never stop inside the roundabout. Instead, continue through the roundabout, then pull over to the shoulder…” (when an emergency vehicle needs to use the roundabout). This would apply in any intersection, but it may be a bit more confusing in a roundabout.

6:10 Advice for pedestrians is good, assuming of course that there is a crosswalk. “A roundabout crosswalk is the same as an unsignalized crosswalk”.” Well, it is an unsignalized crosswalk. More generic good advice.

6:40 “Bicyclists are encouraged to use the crosswalks by walking their bikes.” Sure, bicyclists may become pedestrians and walk their bikes but this is contrary to the current Dutch practice where the bikeway is designed so motorists can yield to bicyclists who are riding, see A person walking a bicycle in a crosswalk is delayed, and delays other traffic, more than one who is riding, and, broadside to the traffic lanes, is a much wider obstacle — and so more vulnerable — than a pedestrian without a bicycle. Don’t expect bicyclists to obey “Mickey Mouse” advice, but do expect them to get into trouble when crosswalks aren’t designed for safe yielding at bicycle speeds. Safe practice in a crosswalk which is not designed to work at bicycle speeds is to slow or stop before entering the crosswalk, allowing drivers to yield, and then cross quickly, but not all bicyclists may recognize the need to slow, and brakes also occasionally fail. Safest practice is to design crossings so everyone can see clearly and yield, regardless of who is required by law to yield. A roundabout should have ramps to/from the sidewalk, aligned with the direction of travel on the roadway, so bicyclists may enter from the roadway and exit to the roadway…see page 168 of FHWA document here: A Wisconsin page giving roundabout resources includes a link to a video describing both options for bicyclists (near the end of the video).

6:50 “If you choose to ride through the roundabout, the same rules apply for a bike as for an automobile.” The bicyclist is hidden behind a truck while crossing a leg of the intersection and then exits at the next leg, properly centered in the outer lane. The bicyclist would have been vulnerable to a right hook if the truck had turned right at the first exit, and would have been safer merging to the inside lane, and then back to the outer lane — or even better, not riding next to the truck, as was previously suggested in the video. The video image does not show a conflict with a bicyclist exiting from the inside lane, though this problem is shown (and bad advice is given) earlier in the video for motorists. Also, if a roundabout is designed for a 20 mph speed, riding through it is not nearly as intimidating as the video would make out — and a bicyclist in the roundabout is not going to cause nearly as much delay, if any, as one in a crosswalk or bikeway outside the roundabout– granted that riding in the roundabout is only for confident bicyclists.

7:54, again: “Never pass or drive adjacent to a truck in a roundabout.” This is exactly what the bicyclist was shown doing.