Rear-view radar reviewed

Garmin is a high-end manufacturer of GPS devices for bicycles and motor vehicles.

Garmin has posted an ad for a cycling “radar” (probably actually LEDdar using pulsed infrared light), which warns cyclists of overtaking traffic. There are some serious problems with the product concept and with the ad, so once you’ve viewed the ad, please read on.

The $200 Garmin device, an accessory for a bicycle GPS unit which costs several hundreds of dollars, informs the cyclist that a vehicle is about to overtake. But in order to decide what to do about that, the cyclist needs to know how much clearance the vehicle will give. The Garmin device doesn’t provide that information.

The stilted British voice in the ad conveys an air of authority, I suppose, but how is the cyclist in the ad not going to HEAR the huge truck approaching from behind? Unless the cyclist is listening to something at top volume on headphones — but I didn’t see any. The cyclist never once is shown looking back, and he isn’t using a mirror, and so what is the device supposed to let him know that he wouldn’t know anyway? Granted, the device could give a warning of a quiet car.

The “cyclist’s eye view” clip in the video shows his response to the warning: pulling over to the right edge of the roadway, so far that grass would be brushing his right foot and he risks a fall on the cracked pavement — which could turn a brush-by into a fatal.

Imagine what a nuisance this device would be when being passed by strings of vehicles. It would give a continuous warning, which would provide no useful information. One more good reason to use my $15 rear-view mirror to check on overtaking traffic, and use my cell phone for GPS (no extra cost) and forget Garmin!

The ad repeats the figure from a League of American Bicyclist survey of fatal bicycle crashes, that 40% are in overtaking crashes. That widely publicized number has several problems though:

  • First of all,  there are more problems with the numbers. My friend Patricia Kovacs comments:

    LAB’s Every Bicyclist Counts study found 40% of bike fatalities were hit from behind. I’ve been studying crash data in Ohio and in 2015, 30% of bike fatalities were hit from behind. But not all hit from behind are the motorist’s fault. In Ohio, 15 out of 24 fatal bike crashes were the fault of the cyclist, 6 were the fault of the motorist and 3 were no error, according to the police officers’ reports. What were the circumstances for the cyclists at fault? Improper crossing, not visible, failure to yield, lying or illegally in roadway. Most of these circumstances can be mitigated with education. I do worry about drunk and distracted drivers though, which is why I use a mirror.

  • The LAB study is biased in covering only fatal collisions, which are rare. Just as an example, in the over 100 million miles of travel in the 50-year history of the bicycle club to which I belong, approximately 1000 lifetimes of riding for an avid cyclist, there have been only two fatalities to club members. One was a rear-ender and the other was a head-on collision with an out-of-control vehicle that crossed to the wrong side of the road. Non-fatal crashes are hundreds of times as common and result in far more loss of years of useful life. 3/4 of serious bicycle crashes don’t involve a motor vehicle at all.
  • The League puts forward the 40% figure to promote its support for barrier-separated bikeways in urban areas, but fatal overtaking crashes occur mostly on rural roads. Most urban fatalities result from crossing and turning movements.

Half-truths have been used repeatedly to sell cycling infrastructure (as with the League’s study) but Garmin’s is the most sophisticated use of half-truths I’ve seen so far to sell a cycling product, while also being seriously ill-informed.

The Slow Ride, redux

Bob Sutterfield writes:

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

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

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

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

Misleading poster redux

seattle poster

Seattle poster

The panel at the right is from a poster called The Commuter Toolkit put out by International Sustainable Solutions for an organization called the International Sustainability Institute. You may view it full size by clicking it or view the full poster. This poster shows a scene in downtown, Seattle, Washington, USA and the poster bears the names of various sponsors in the Seattle area.

The comparisons of space used by different travel modes in the poster are misleading. They show the space which people occupy standing still in posed photos, not the space which each mode of transportation actually uses. Cars would not be spaced so closely if in motion, and they also take space to park. Nor would buses be spaced so closely, and they also use bus stops and bus garages. The bicyclists are standing over their bicycles, not riding, etc. Neither does the poster address the throughput and travel times for the different modes or the suitability of different modes for different trips of different distances. I addressed an earlier example of a similar poster on this blog but there’s a twist to this particular version: the bicyclists are shown riding down the middle of Second Avenue in Seattle, but look over to the right side of the picture: that’s a bike lane — also with cars in it in the car picture. Similarly for the bus-only lane at the left side of the photos. No train runs on this street!

The bike lane was more recently replaced by a two-way separated bikeway, into which speed humps are being installed because the bikeway cannot safely support normal downhill bicycle travel speeds on this sloping street, though that’s another story.

The location, in case anyone wants to take a closer look.

Lane Control on Lexington Street

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

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

Lane Control on Lexington Street from John Allen on Vimeo.

Bruce Epperson’s observations on transportation funding

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

Wow, it’s a laser!

A post on the Grind online news site heralds the Blaze, a  laser bicycle light gimmick — not the first to be reviewed on this blog The Blaze hits the market with some rather clever — and deceptive — advertising including the photo below.

The Blaze shown to best advantage

The Blaze shown to best advantage


The camera angle in the posed photo is chosen very carefully to create a specular reflection off the wet pavement. That makes the projected bicycle image look much brighter in this night photo. It will be totally invisible in daylight. Cost is 125 British pounds, that’s about $187 in US dollars and there are lights with similar performance (other than the laser feature) for $70. See

The idea of the light also appears to be to warn motorists who might make hook turns. There is a better way to avoid hook turns: don’t overtake on the curb side of a motor vehicle. And in any case, the bicycle image which the laser casts on the street, if visible at all, isn’t far enough ahead of the bicyclist to be in the field of view of many drivers in time to avoid turning — particularly not the drivers of long vehicles which are involved in the largest number of hook-turn fatal collisions.

Helmet disparagement and ethics

To quote the late, great Dutch traffic engineer Hans Monderman, “Never treat anyone in the public sphere like an idiot. If you treat him like an idiot, he will act like an idiot.”

There is an issue with the difficulty of providing helmets when bicycles are rented from unstaffed kiosks. Bike-“sharing” (actually rental) has unleashed this problem, in the interest of increasing bicycle mode share, and has been accompanied by a flurry of pronouncements disparaging not only mandatory helmet laws, but also helmet use.

Purportedly, according to several reports which have appeared in the media, wearing a helmet actually decreases safety. The quintessential article appeared in the New York Times. You see, it works like this: helmets make bicycling appear hazardous. If we don’t convey that impression, more people will ride bicycles, and then there will be a safety in numbers effect, so, what, me worry, all will get better.

In my opinion, bicyclists’ helmet use deserves to be a matter of personal choice rather than law. That is, I would like to rely on individuals’ own intelligence and judgment, and on helmet promotion, rather than to treat people as idiots, on the one hand disparaging helmet use in the interest of some Greater Good which is supposed to accrue to society at large, or on the other, passing a law which is supposed to force helmet use, but goes unenforced nd raises an issue of presumption of negligence as in, “the driver ran a stop sign, but you weren’t wearing a helmet, and so you were breaking the law and can’t collect on the driver’s insurance.”

I personally have had 3 serious impacts between a helmet and pavement the past 37 years since I started wearing one. One incident was initiated by a drunk driver. One was a collision with a tree branch hanging over the curb and which got caught in my front wheel, downhill at about 17 mph; the third, an encounter with an pothole at 8 mph. Note that two of the three were single-bike crashes. No bicycle-facilities nirvana is going to prevent these. Actually, crowded conditions on separate bicycle facilities make bike-bike and single-bike crashes more likely.

Am I to believe that the health benefits of cycling would be far greater than the injuries I would have suffered if not wearing the helmet, or for that matter, whether I would still be cycling, or in full possession of my faculties, or even alive?

I’m not alone in having such stories, or in saying that I wouldn’t ride if I couldn’t wear a helmet; helmet use became almost universal in recreational bicycle clubs within a few years after effective helmets became available in the mid-1970s, and bicycle clubs thrived. Helmets cut both ways, both encouraging and discouraging bicycling. Debris, potholes, riding in close quarters with other bicyclists of widely varying skill, all lead to crashes, and I challenge anyone here to explain how increasing the number of bicyclists or building separate facilities improves that situation except perhaps if the facilities become so crowded that bicyclists are reduced nearly to walking speed.

My choice to wear a helmet has nothing to do with the Greater Good, one way or the other. I’ve made my choice and it has worked very well for me.

Helmet disparagement is, to put it simply, deception. By way of comparison, recruits into the military are not deceived about the risk they assume, but they may take it on for patriotic and/or career reasons (or back in my day, be drafted). Special benefits, compensation and medical care if injured are part of the deal. Byut bicycling isn’t the military. I ride on my own initiative, for transportation and recreation.

User agreements for bike share customers (typically, several screens long on the rental kiosk, but where the agreement can be signed without reading it) relieve the renter of responsibility. I’d suggest that one way to promote helmet use would be to offer insurance if the customer wears a helmet. This, unlike a mandatory helmet law, would be a positive incentive.

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

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

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

First paragraph of the abstract:

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

You may read the entire manuscript here:


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 (and least expensive) 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 like 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.