In recent days I've noticed this this mudflap appearing on some heavy vehicles, like this cement truck:

Here's the sign in detail:

Warning. Danger zone. Beware when this vehicle is turning left. Do not pass on this side.

[Note to readers in drive on the right : passing on the left is an inside pass in .]

Such signs are available in other countries but I don't know how widespread is their usage. I like the idea, for two reasons: it shows that at some level the trucking industry is concerned about the safety of vulnerable road users, and it's a clear, simple message that's in the right place to be an effective reminder at just the right time.

By design the graphic is unambiguous and easy to comprehend in an instant, which is good for the approaching cyclist who may be processing any number of stimuli when they encounter a turning truck.

While it's not a mistake that I'm likely to make—I'm pretty wary of making inside passes on any turning vehicle (although I did make an unwise inside pass on a mini street sweeper the other day…)—there's really nothing wrong with a timely reminder not to do anything excessively risky.

Of course I'm not naïve enough to believe that a mere sign is enough to prevent all truck-bike collisions, but this must surely help. So I guess it would be good if these signs became standard on all trucks—but then I wonder if they could lose some of their effectiveness if they were 'everywhere'.

What do you think of this idea?



Turning on the inside (left) isn't to be highly recommended, for extremely obvious reasons.

Cycling Safety Tips: Heavy Vehicles & Cyclists


Best cycling sign I've seen, errr, unless I come across something like "Free Beer for Bicyclists" ;-) .

I'd never contemplate undertaking a heavy vehicle anywhere near an intersection, but I think that comes down to experience/confidence (usually just go round on the right). Still I see plenty cyclists that do, apparently oblivious to the inherit dangers. This sign just says, no don't do it, at the very least it will make a cyclist think about it a bit more.

Karl McCracken (twitter: @KarlOnSea)

Along similar lines, this home-made one was spotted by Adrian Fitch in London last year

Surly Dave

I wasn't so sure at first, but on reflection it's not a bad idea, if only because it indicates a growing awareness of the hazards cyclists face and an effort to mitigate them.

Treadly and Me

Threre's another really good video on not tangling with trucks here: Be aware of lorries


In the USA, trucks (aka lorries) often have "Passing Side / Suicide" pasted either on the mudflaps or on the back of the truck, e.g. This photo -