Driving in to work this morning, I got stuck behind a truck and had some time to appreciate its backside. I noticed something that I’d always wondered about: there’s a warning label telling you that the truck takes wide right turns. Why is there no warning label telling you that the truck takes wide left turns?
If I had a chalk board, hell even a dry erase board, this would be easier to explain. The radius of a right turn is shorter than a left turn (??). Basically, a left turn by highway design is already a wide turn, where a right turn (by highway design) is tighter.
Maybe someone can explain this more elegantly.
Because they don’t make enough left turns from one one-way street to another one-way street to make it worth printing all the warning signs, and the circumstances under which they would apply. If they’re going to or from a two-way street, the left lanes make enough room for them to turn.
Because they’re already wide! A ‘non-wide’ right turn (or left, if you’re on the correct side of the road 
) would cause the trailer unit to cut the corner and mount the kerb, or demolish a wall, or whatever. So the driver swings out into the middle of the road to compensate. This is particularly a problem if somebody behind sees that he’s about to turn, tries to overtake, and ends up on a collision course. With a turn across to the far side, there’s the open space of the road for the trailer to cut across.
When taking a wide right turn the truck will do a right from the left lane, or at least weer left before turning, and thus cut across the right lane scaring the living bejeesus out of you if you weren’t expecting it to. When taking a wide left turn the truck will cut across the lanes going in the opposite direction, which will hopefully be empty of cars, especially of cars having had the opportunity of reading signs at the back of the truck.
And I can see in preview that everyone and his uncle has already answered this, and more, but I’m posting anyway.
Because all left turns are wide turns. Normally right turns are not wide turns, but the truck w/ trailer is so big it needs to make a wide turn. The warning is only needed for the turn that does not fit the norm.
Leading one to pose the inevitable follow-up question: Do British trucks (lorries?) bear placards warning that “this vehicle makes wide left turns”?
No no, Trucks take out Utility poles and signs when taking turns over here. Most times cars over here have to back up and give more space to the semi.
This is actually something I’d wondered about for a while. Thanks for the responses.
Yes. Some do, anyway, but they’re not all that common.
I’m surprised these signs are not universal. In Australia, not only do they have the signs, but you will get a kickarse fine if you pull alongside a truck trying to turn.
The signs are “DO NOT OVERTAKE TURNING VEHICLE”. Of course wags have been known to make homemade ones for dumped cars: DO NOT OVERTURN TAKEN VEHICLE. 
But yeah, trucks have a rigorously enforced legal right to use multiple lanes for tight turns. There are also signs “IF YOU CAN’T SEE MY MIRRORS, I CAN’T SEE YOU” on the back of trucks. These aren’t a legal requirement, but they’re a good idea given that car drivers’ stupidity regarding heavy vehicles seemingly knows no bounds.
It’s over twenty years since I had driving lessons but I can still remember my instructor emphasising the “do not overtake turning vehicles” rule.
Sure they do.
The difference is much of the right turn is in the truckers blind zone.
Once the turn is started the mirror only shows the trucker the trailer.
During a left turn the trucker can just look out his window to see traffic.
Also, the needed sweep is a function of rear gear placement. If the trailer has a California axle, that becomes variable.
Yes - and it’s in the Highway Code.
This is true. But it’s a fault of driver training if they don’t know how to deal with such an everyday hazard by the time they get their licence.
What? Driver training in the US? Where? You mean in opening the Cracker Jack box? :rolleyes:
While I see some trucks mounting the curb on some turns, I have seen other trucks making the same turn w/o mounting the curb. This is in situatiuons when there is no room to make a ‘wide turn’. Does this mean that trucks are able to make a non-wide turn and it’s all the driver’s skill?
Also what is the legality of the ‘wide turn’?
It just goes to show you that not all trucks are equally manuverable and not all tight turns are equally tight. And some drivers are roaring drunk.
As far as the legallity, IIRC, American driving guidelines (and most state laws) advises attempting to stay within the nearest lane when making a turn. I don’t ever recall reading that this is an absolute legal necessity at every intersection.
Most traffic laws leave much discretion to the enforcement officer. The Basic Speed Law common to many states is one example. I have never heard of a statute that gives a specific number when determining if a driver is executing excessive lane changes. Read your own state’s traffic statutes sometime. They’re available in your local library.
There are no gears on a trailer.
I think he meant ‘gear’ as in running gear, not ‘gears’ as in a transmission.
I am wondering just what a California axle is, though.
DD