What Cyclists Need to Know about Trucks
Cyclists hit by turning trucks is a repeating news story which highlights the most serious deficiency in our system — education of cyclists. Sometimes these crashes are caused by the truck driver passing a cyclist prior to turning right, but very often they are caused by the cyclist passing the truck on the right. In both cases, the cyclist has the power to avoid the crash.
Here’s how YOU can keep this from happening to you:
- Do not stop at an intersection on the right side of a truck. If you have already stopped in a bike lane and a big rig pulls up next to you, don’t assume the driver has seen you. Get off your bike and move it to safety (your life is worth the inconvenience). It’s better to stop in the middle of the general traffic lane if you arrive first. (In many cases it’s safer to stop in the line of traffic than to pass the queue.)
- Do not linger next to a truck on any side, in any lane. If you are riding near the same speed, slow until you are behind the truck. (This is taught to motorcyclists, it applies to all vehicle drivers, even car drivers!)
- If a truck passes you, slow down and let it get ahead of you ASAP. If you are approaching an intersection, merge to the left and ride near the center line to avoid the moving blind spot (see Left Cross in the Blind Spot).
- If you are in a bike lane and passing stopped traffic, do not pass a truck unless you can be clear of it before approaching any intersections or driveways and before traffic begins moving again. (This is a case where bike lanes offer a false sense of security that can get a cyclist killed.)
- Or, just don’t pass a truck on the right at all. And be cautious when passing on the left, too.
Trucks make wide turns. They cannot physically make a right turn from the right curb, so they will often leave a large, inviting opening on their right prior to a turn. They will also move straight into the intersection before starting to turn. When a truck turns right across your path, it is almost impossible to escape its rear wheels. So don’t get caught in a spot where this can happen! Be aware of what kind of situation can lead to a potential crash and avoid it.
Here’s an example of how blind-spot awareness saved my life last year.
I was riding North on Magnolia through downtown. I was in the bike lane. Approaching Concord, I saw a slow-moving truck in the right traffic lane. I slowed and hung back. We continued to Colonial, where the light was red. The bike lane is properly-striped to the left of the right-turn-only lane, so it would be correct for me to ride in it to the intersection. But the truck was in the right thru-lane and I don’t ride next to trucks. I decided to pull into the thru-lane behind it. Just as the truck reached the Colonial intersection, the light turned green. The truck driver turned on his right turn signal and turned right — across the bike lane and the right-turn-only lane. Yes, he made an illegal turn. He probably checked his mirror for cars in the turn lane, but he would not have seen me. He never did see me, I nonchalantly passed him on the left and went on my way. But it was not lost on me what would have happened had I made a different decision. And I wondered how many other cyclists would have made the same decision.
Acute awareness of vehicle blind spots was taught to me in motorcycle safety school. Perhaps if bicycle advocates and the bike industry put as much emphasis on education as the motorcycle industry does, I wouldn’t keep seeing articles like the following:
Here are 2 crashes from this month. Both of these cyclists were very fortunate to survive.
11/25/08 Elderly bicyclist injured in crash with big rig
[The cyclist] and the big rig were both stopped in the street waiting for a train to pass prior to the crash. Once the train passed, the big rig made a right turn from Lemon Avenue onto a side street, striking the still stationary bicyclist.
Note: the satellite view shows what appears to be a wide curb lane. Wide curb lanes allow cyclists to ride on the right of traffic, but cyclists should still be cautious about passing stopped traffic. If you suddenly find yourself in a situation where traffic is stopped and you are next to a big rig. Get off your bike and get off the road.
11/18/08 Cyclist Down: Fillmore and Fulton
The cyclist’s description: “I was cruising down Fulton eastbound and saw the truck ahead of me. I sped up a bit so I’d stay within range of his rearview mirrors. If I were too far back, the box part of the truck would block me. We approached the intersection and I was keeping an eye on his turn signal because I was passing the cars. I was going about 20 and there was no turn signal. As I came towards the intersection, I saw he was turning and hit the brakes. I skidded into the side of the truck and he kept turning, which pulled me under.”
Note: Fulton street has downhill bike lanes which are dangerous because cyclists can travel at motoring speeds. Any time you are traveling at downhill speed, you should be in the traffic lane. You need way more room to maneuver than a bike lane provides. If you are traveling faster than traffic, it is safer to pull into the traffic lane and slow to the speed of that traffic than to fly past it on the right. This allows you to easily pass right-turning vehicles on the left, instead of being hit by them as they cross your path.
Here are 4 more that have happened in the last 14 months. These cyclists were not so lucky. (All of these crashes involved cyclists in bike lanes.)
Cyclist, 22, Dies After Being Hit by Truck Near Dupont Circle
Cyclist killed in crash well known in Portland
Full cement truck drives over and kills cyclist ‘in an instant’
Bicyclist killed in dump truck crash identified
John Allen lists a bunch more in this article about mindless passing on the right (and how bad bike facilities encourage it while we educators are trying to discourage it).
When you know how to be safe around trucks, it won’t happen to you!
Check out this interactive graphic showing how trucks turn on iamtraffic.org
Here is a video for cyclists by the Portland Water Bureau.
I also found this video from the trucking industry. This is aimed at motorists and highway driving, but it has some good blind spot images in it.
One thing that’s frightening to consider is that too many cyclists feel (or state in messages on cycling related groups) that they are entitled to move ahead of stopped traffic. I have been chastised for saying that I remain in the traffic line, even though there may be an open bike lane or shoulder available for me to pull to the front “as is my right” which I find preposterous.
Another rider/poster commented that he refuses to follow traffic laws as it infringes on his right as an individual to do as he pleases on his bicycle. He touts being fifty-five years old and rides against traffic, two feet from the curb. I suppose he won’t get “trucked” by riding up the bike lane, doing that!
Where I live I have a legal right to pass stopped cars, so I guess I am entitled. From the DC vehicle code:
1201.3 (a) A person operating a bicycle may overtake and pass another vehicle only under conditions which permit the movement to be made with safety.
(b) A person operating a bicycle may overtake and pass other vehicles on the left or right side, staying in the same lane as the overtaken vehicle, or changing to a different lane, or riding off the roadway, as necessary to pass with safety.
(c) If a lane is partially occupied by vehicles that are stopped, standing, or parked in that lane, a person operating a bicycle may ride in that or in the next adjacent lane used by vehicles proceedings in the same direction.
1201.3 (a) A person operating a bicycle may overtake and pass another vehicle only under conditions which permit the movement to be made with safety.
If you get run over by a truck, the movement couldn’t be made with safety. But hey, be entitled. It’s your life.
Keri- this page on avoiding death by truck is very informativer and valuable, but ill-informed generalizatons aren’t. Fred’s criticism of what he perceives as improper behavior by fellow cyclists is contrary to the laws in some states. I’m not saying you should ignore the dangers of right-turning cars- but the law does provide me with several options in handling an intersection with stopped car. An experienced cyclist can recognize that situations need to be evaluated on a case-by-case basis. There is a school of thought that says that is is safer for cyclists to pull to the front of the queue – the “bike box”. I can certainly think of some advantages- one is that I am less likely to be rear-ended by a driver texting if I am shielded by parked cars. The bike boxes are designed to address the right-hook risk, and include a recommendation to pass cars to get to the box:
Fair enough, Marc.
It is possible to pass a queue safely, although I rarely see cyclists doing it safely. It is also appropriate in congested traffic to carefully pass a queue. In CyclingSavvy classes, we discuss how to make safe decisions regarding passing slower traffic — there are lots of hazards to be mindful of.
The problem with bike boxes is that they have no function when the light is green. They only work for a bicyclist who has gotten into the bike box during the red phase. Because they encourage bicyclists to try to get to the bike box, they increase exposure for those who don’t make it before the light changes.
Put in human terms, it is possible a bike box might have saved Tracey Sparling and Dennis Dumm, but not Brett Jarolimek, Alice Swanson, Kimberly Yeong Sil Hull or Bonnie Tinker. Understanding the operational characteristics of trucks and the human-factors limitations of their drivers might have saved all of them.
Paint is static, traffic conditions are dynamic. You simply can’t paint safety onto the road. Safety is a product of informed behavior.
All the cyclists I’ve known over the years that made a habit of passing stopped cars on the right have “interesting” stories to tell.
Passenger doors opening, cars swinging right to start a u-turn, cars making an unexpected right turn. Motorists get impatient sometimes and do things that a cyclist wouldn’t expect. This gives the “experienced” cyclist another situation to cite when talking about how dangerous it is out there.
Good observation, Eric.
That was certainly true for me. Before I understood the problem, I had an extremely negative view of motorists that was largely based on constant bad experiences while passing the queue on Edgewater Drive.
Cyclists have the same mindless passing behaviors for stopped traffic that motorists have for passing cyclists… no matter what, they must pass… it doesn’t matter if the traffic is moving slowly through a stop sign, it doesn’t matter if the cars have turn signals on, it doesn’t matter if there are only 2 cars in the queue or if they will have to pass the cyclist again in a narrow lane, it doesn’t matter if there are large blind spots they must cross… cyclists must pass slower traffic… cyclists must pass slower traffic… cyclists must pass slower traffic… and sometimes the insistence on doing it gets them maimed or killed.
Much as we think our s_ doesn’t stink, thoughtless driving is a human failing not limited to motorists.
Great article, Keri. I like how you relate these techniques to motorcycle safety, makes it more interesting to read. I’ve slowly learned some of these techniques from experience and close calls, but it wasn’t until the October fatalities here that I really started to think carefully about the dangers of coming up on the turning-side of a long truck. Hang back or shoot ahead (or change lanes on multi-lane one-ways).
Maybe bicycle safety education will have the appeal of motorcycle safety education someday. Maybe even integrate the two under a single organization. Probably easier to teach MSE, since you don’t have to teach things like “ok, here is when you must disobey the motorcycle lane stripe.” 🙂
As always, an excellent post with great illustrations as to why “passing on the right” is dangerous, and yet it is something that far too many cyclists believe is one of the advantages of the bicycle as a vehicle… the “vehicle of opportunity” excuse.
Great site re-design, btw.
I am truly sorry that I am going to disagree publicly with PM Summer, whom I admire and greatly respect.
The illustration of the turning truck is not right. As drawn, the trucks rear tires will encroach 2 or more feet onto the sidewalk!
The phenomena happens with all vehicles: when turning, the rear wheels will “track” closer to the inside of the turn. On a bicycle it is very small, and in cars it is measured in inches. But with a tractor-trailer combination vehicle (Where the rear dual wheels can be as much as 48 feet from the king-pin!) the off-tracking can be more than three feet.
Ironically, the artist is depicting what many people expect a turning truck to look like.
To fix the illustration, the cab of the truck would have to continue straight until it was well past the beginning of the cross lane before starting his turn. Otherwise the rear wheels would mount the curb.
It would not be unusual for a cyclist to think the truck were going straight through the intersection at first. Suppose the truck is stopped at a signal while a cyclist is approaching the intersection. The cyclist proceeds to pass the truck as the light turns green. The truck will move out into the intersection with every appearance of proceeding through it, while the cyclist moves into the “killing zone”. Or as Keri put it so well, “they will often leave a large, inviting opening on their right prior to a turn.”
Once the truck begins his turn, there will be no way for him to perceive your distress. All he can see is the forward part of the trailer in his mirror. He will not even hear you scream. I would recommend avoiding finding yourself in that position.
Good article, good comments. I may be picking at nits.
Merry Christmas everyone! ChipSeal
ChipSeal was right about the drawing. I worked on it some more and replaced it.
Excellent Keri! Well done! The addition of the trailer tire tracks makes the dire situation very clear. Perhaps even the P&P folks could understand it. Tailwinds!
I viewed the Portland Water Dept. video, and all I could think, as I saw those cyclists riding in the bike lane, was “Don’t ride there! Don’t ride to the right of traffic which might turn right!!” It’s very simple, cyclists–just don’t do it! Don’t depend on the poor driver to see you–stay out of the danger zone–which is anywhere on his right side!! Don’t ride in the bike lane!!!
The voice-over urges us to “Be visible”–well, riding in the bike lane makes us LESS visible! I admit, I have not ridden my bike in Portland, but I hope to do that this fall. And I’m damned if I’ll ride in a doorzone bike lane. I will NOT ride where it’s dangerous!
When you ride in a bike lane, you have to be vigilant, always looking out for things you must avoid, obstacles, debris, potential conflicts with crossing and turning motorists, etc. When you ride visibly in a traffic lane, you can relax just go along your way like any other driver. Bike lanes INCREASE work load! Go figure.
If cyclists could get over the fear of “being in someone’s way” they’d never, ever advocate for such marginalization.
Riding around trucks scares me to death. That is why I take control of the lane, especially at intersections.
I recall the latest deaths by truck in the Portland area and the driver “did not see” the cyclist in one of them. If the cyclist had not been in the bike lane, had taken control of the lane of travel at the intersection, and made her position and intentions obvious to the truck driver, the outcome could have been different.
Confidence and education play a large part in reaching our destination safely.
Keri mentioned about “not over glorifying hi-vis clothing” in another post. Unless I am on a MUP, you will find me riding the streets in my lime green reflective vest. Personal choice, not necessary to operate a bicycle safely.
If you have met some of the “outstanding motorists” here in Orlando, or in your locale, it is understood WHY I don’t want to give any margin of error with regards to my safety.
We will ride with our fallen cyclists again someday. Until then, ride safe and ride BIG!
Are bike lanes in essence more dangerous to the cyclist than having none? Do they present feeling of safety? Might they overlook a truck to the left of them with a turn signal on? What is the turn is made by a truck mid block into an establishment or parking lot rather than an intersection? What can be done to avert these tragedies? Are there mirrors that prevent blind spots?
My nephew was run over by a cement truck while he was in a designated bike lane as the truck turned left mid block into the company parking lot. I wonder if the outcome would have been different if he were behind the truck. He was conscious of safety. He ride motor cycles. As a firefighter, ambulance runs were a daily occurrence. He was alert by nature and aware by experience, yet he was killed.
What can we do t make bike lanes safer?
I’m so sorry you have lost your nephew. Stories like this break my heart.
Unfortunately, bicycling safety is not as intuitive as it should be. One reason is the stigma our society has attached to it — the belief is that bicyclists must stay out of the way as their primary objective. Another is the idea that cyclists should take advantage of their narrow profile and pass stopped traffic (perhaps to make up for being slow and shoved out of the way).
The problem with bike lanes is they reinforce both of those things. They discourage a cyclist from riding in a position that would prevent a truck from passing immediately before making a turn, and they encourage a cyclist to ride past a stopped truck. There really isn’t any way to make bike lanes safer in the face of these human factors.
There are mirrors that can help a truck driver see into his blind spots, but it is still a human-factors challenge. The driver may need to focus on what’s ahead or around the turn. Or he may just be distracted. Not putting the cyclist there in the first place is by far the best solution.
I began my journey as an advocate trying to find a way to make bike lanes safer (because of conflicts I kept having in them). My research led me to the conclusion that the best solution is to get rid of them—at least in an urban environment where there are lots of driveways and intersections.
The best solution for cycling safety is to promote cycling education. It may seem counter-intuitive, but because cyclists are nimble, relatively slow and have 360° awareness of their surroundings, they are at a tremendous advantage to prevent crashes. They just need some knowledge of traffic dynamics and where the dangers are. Door zones and turning trucks are two killers that we really need to teach people to avoid because most just aren’t aware. But education is made much harder by paint that contradicts it.
Not to mention so many bike lanes are poorly designed, and often useless to cyclists.
Regarding cyclists who have every legal and moral right to use the roadway I refer them to Murphy’s Law of Combat Operations: 37. Anything you do can get you killed, including (doing) nothing.
Be aware of your surroundings. Pick your fights. Don’t stay in blind spots no matter how legally protected you believe yourself to be. Assume that the truck driver does NOT want to hurt you, but that he(she) can not protect you if they can not see you. (Hint: If you can’t see them, they can’t see you.)
Me? 1.8 million miles of trucking — cyclists injured NONE!
People bicycling fare best when they are in the way.
I am a fleet manger of a group of truck drivers and a a cyclist. Thank you. I am going to show my guys this post.
What trucks need to know about trucks. They have turn signals. Use them. I’ve had so many close calls with cars and trucks who don’t use turns signals. Chastising bicyclists misses the point. A bike has never killed anyone driving a truck.
Nothing in this post is “chastising bicyclists.” This is information to help bicyclists avoid mistakes that can kill them — be it their own or another’s.
what a horrible way to present decent advice… it’s like saying if you don’t want to get sexually assaulted then don’t wear a short skirt…
the best thing to fix this problem is by holding the truck driver responsible for their actions… a small fine or community service won’t send a message to people to look where they’re going… charges of manslaughter and the threat of life in prison for taking another person’s like in a careless way is the best way to prevent future incidents…
don’t foster fear, instead foster education and enforcement by those doing the killing…
“the best thing to fix this problem is by holding the truck driver responsible for their actions…”
Nowhere in the world has this argument been persuasive. In the UK, “cow catchers” are installed on trucks which are guards between the wheels so that when the truck sweeps right, in theory, the guard pushes the cyclist away . . .
My advice to anyone that will listen is, “Do not pass on the right.” and “Do not ride up past a line (or queue) of cars or trucks on the right” because it causes nothing but trouble. I don’t care if it is legal or not.
Instead, queue up with the rest of the vehicles of which, by state law, you are one of. Some people get upset with that advice. “Where is the advantage to riding a bicycle if one can’t get ahead of the traffic?”, they say. In my mind, there is no advantage. Riding a bicycle and how it rests the mind is the only advantage needed, although it is not as restful in heavy traffic.
although the advice of “don’t do anything dangerous even if it’s legal” would be best followed by removing the dangerous motor vehicles from the road I believe it’s better to give people freedom to do dangerous things, but as I originally said they need to be responsible for their actions when doing dangerous things like operating a motor vehicle…
without the motor vehicle the bicycle is rarely deadly… without the bicycle the motor vehicle still kills tens of thousands a year…
now what was that thing you were advising us against?
Are you saying truckers should be responsible for people sneaking into their blind spots?
yes, I’m saying people should be responsible for not running into things… I don’t care what you’re driving, you need to be sure that the lane next to you (bike or motor-vehicle) is clear before you cross it… saying you didn’t see something that was there is an admission of guilt… you have to be sure that you saw that the space was clear… a bike lane is a legal lane of travel for a vehicle just like any other lane on the road… it’s no different than changing lanes… you don’t put on your turn signal and then blindly change lanes and then blame any smaller vehicle that happens to be in your path while they’re legally traveling in their lane…
You might have missed the caption on the diagram: “Trucks have huge blind spots. Truck drivers cannot see little things in their huge blind spots. Large vehicles off-track when turning, so they will appear to be going straight and often swing wide before making a right turn.”
I wonder how conscientious, hard-working, professionally-trained truck drivers would feel about being compared to rapists and murderers.
Hi Spiffy, I can see where you’re coming from, but I think your analogy is fallacious. The statement that a short skirt is asking for it is something we can all agree is wrong. It’s wrong because it says that a man has no control over himself when he sees a woman dressed provocatively and therefore rapes her and its her fault. In reality, if a man rapes someone, its his choice, he CHOOSES to do something wrong, and assigning blame to the victim is absurd.
Contrast this to the issue discussed in the post. Trucks have large blind spots, this is an indisputable fact that is a result of plain geometry and physics. It is therefore impossible for a truck driver to see certain areas around his vehicle. If a truck driver turns into a cyclist because the cyclist was in a blind spot, then there’s no choice or intent of doing something bad to the cyclist. A truck driver could be doing everything legally (checking mirrors, signaling, obeying traffic signals), but still run into a cyclist he can’t see. Is that his choice? Is it even something he could conceivable prevent? I don’t think so, beyond quitting truck driving. I think blaming the truck driver is like cursing gravity when you fall and scrape your knee. A rapist has a choice whether or not to rape a woman, but does it anyway; the truck driver is not given a choice if there’s a cyclist hidden by a blind spot. To get an ideal world where there is no rape, you have to change human nature, but to get an ideal world where a truck has no blind spots, you have to change the laws of physics, not the driver.
But should the cyclist be faulted if they get hit? If a cyclist doesn’t know about a truck’s blind spots, then no, punishment for ignorance is pointless. But if the cyclist knows about a truck’s blind spots, then they can easily avoid them and stay safe. This is where your short-skirt analogy makes a little more sense. It is common sense to do things to avoid dangerous situations. I have a friend who counsels assault victims and what she tells them is it’s never their fault, that in an ideal world they should be able to walk down the darkest alley, naked, drunken and stoned out of their skulls and never be touched: it’s the rapist that is the person who makes the choice and is the guilty party. But you can take measures to protect yourself. I mean, think about your front door. I’ll put money on it that you lock your front door. Should you have to? Is it legal for someone to come into your house and steal your stuff? No, but you lock it anyway, just in case, to protect yourself.
You can’t protect against everything, life is unpredictable, but in the case of a truck which (if you’re educated about such things) you know has blind spots, you don’t have to guess. You protect yourself by staying out of its blind spots.
“But you can take measures to protect yourself. I mean, think about your front door. I’ll put money on it that you lock your front door. Should you have to? Is it legal for someone to come into your house and steal your stuff? No, but you lock it anyway, just in case, to protect yourself.”
There is an easy answer, and one I’ve used through forty years of adult cycling.
Don’t pass trucks or any other vehicle on the right. They can’t see you in the blind spot. Get out of the gutter, or bike lane, and merge into the lane behind the truck. Wait your turn. Act like a driver.
Should driver be held accountable for their actions? Sure, just like everybody else. But consider that YOU are the primary person responsible for your safety. If you put yourself in the blindspot of a vehicle that can kill you- you just gave up the control of your safety.
Be responsible to yourself.
gears to you….leo
Truck driver initiates a turn, and cyclist tries to pass on the right in a blind location (so the truck driver could not see her) and you compare this to inviting rape by wearing a short skirt? That’s irrational. A better analogy is to imagine a cyclist hiding behind a planter and diving out in front of a construction worker so your head ends up under his boot and cry victim when your head is inevitably stepped on.
The danger of smaller vehicles operating inside the turn circle of larger vehicles is well known, which is why yellow stickers/signs instructing the drivers of sedans not to do so are on the back of large trucks. The same issue is even more hazardous when trying to pass on the right. Here is one of the slides we use to teach transportation professionals about the hazards of right hook turns and how they occur:
Oregon is a strange state because their traffic laws literally require both motorists and cyclists to act in ways that create the lethal conflict we are discussing.
For the right hook boxes (what I’m now calling the ones in Portland), they don’t serve the riders who can control a travel lane to avoid the hook (though such safe behavior is sadly illegal in Oregon), and for those who lack the traffic skills necessary to avoid the conflict, it forces and encourages them into right hook turns on the green phase, since such bike lanes at the edge at intersections are mandatory cyclist use by Oregon law, and motorists must turn across them instead of entering them as they are required to do so in the rest of the US.
The purpose of requiring motorists to merge into a bike lane to make right turns is specifically to preclude cyclists from passing on the right by virtue of the turning vehicle blocking such a line of travel; thus forcing the cyclist to either pass on the left in a safe divergent line of travel, or wait behind until the motorist completes their turn.
It’s truly sad that Oregon law and facilities designs create lethal manufactured conflicts.
The way traffic operates, ie Rules of the Road, has evolved so that traffic movement is safe and efficient. It got this way within the constraints of human factors. “Human factors engineering focuses on how people interact with tasks, machines (or computers), and the environment with the consideration that humans have limitations and capabilities.” So, for example, right turning drivers are expected to turn right from the rightmost lane and are not expected to have thru traffic passing them from behind while they are executing the turn which requires attention to the front.
Placing thru bike lanes to the right of right turning vehicles is a human factors fail. Duping bicyclists with green paint is another human factors fail by making them feel safe and infallible precisely when they should not feel safe and instead should be “on task” and think. This double whammy results in collisions.
Only some of the blindspots shown in diagram from the AAA near the top of this post are also danger zones. One very safe place to be around a big truck is behind it, where you can often read a sign, “If you can’t see my mirrors, I can’t see you.” A more accurate statement is: “if you can see my mirrors, I still might not see you.”
Most of this article addresses the space trucks unexpectedly occupy on the side toward which they’re turning. Some trucks also take up more space on the side opposite their turn.
I was behind three cars that were signaling right, and the cars were slowed behind a truck preparing to turn right. The truck signaled right and swung left, before starting its right turn. The cars had moved to the right, partially onto the shoulder that was becoming a right turn lane (http://goo.gl/maps/gkzBX), so I merged to the left side of the straight-through lane to pass the line of cars.
The truck was a semi tractor towing an automobile transport trailer. The trailer’s loading ramps gave it an unusually long overhang behind the rear wheels. As the tractor went around the corner to the right, the trailer pivoted clockwise about its rear axles without moving forward much, and the rear of the loading ramps moved several feet to the left – even into the adjacent travel lane – before they started following the rest of the trailer around the corner to the right.
If I had not noticed the long rear overhang and had moved myself alongside the left side of the trailer, I would have been surprised by the leftward movement of the overhang. Since I did notice the type of the trailer and its unusual geometry, I held back and delayed my passage until the entire trailer was moving to the right, away from my intended track along the left side of the lane.
Well observed Bob. The reality is that trucks are large machines usually operated by only one person. They are not plush toys so cuddling up to them (the machine) is not recommended, especially when the truck is manoeuvring. For the safety of everyone give trucks some space.