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How to avoid SMIDSY collisions

SMIDSY collision high visibility road safety

SMIDSY (sorry, mate, I didn’t see you) collisions occur, not because motorists don’t look, but because they don’t look twice and when they do they don’t perceive how close we are.

That’s according to a Texas Tech University psychologist who says people think smaller objects are further away than they appear and conversely bigger objects are closer.

Researcher Pat DeLucia reached her finding by testing people in computer simulations.

She studied participants who viewed two approaching objects simultaneously – one large and one small. The viewer had to nominate which would reach them first.

Her study, “Current Directions in Psychological Science”, indicates that an object’s size affects distance perception, causing drivers to miscalculate riders’ distance and speed.

“People generally picked that simpler heuristic: Larger is closer,” says DeLucia.

Unfortunately, motorcycles are the smallest vehicles on the roads, yet are usually the fastest accelerating.

So drivers think we are going to arrive much later than we actually do.

It’s a lethal combination that could be the cause of up to three out of every four motorcycle collisions.

SMIDSY SMIDSY collisionsOk, so what do we do about it?

  • Having headlights on may make you more visible in some circumstances, but it doesn’t make a difference to the size of your bike.
  • Position on the road is important. You need to ride in the wheel track closer to the centre line as this means you are visible sooner to oncoming traffic or vehicles turning across your path. It also gives you a buffer from vehicles suddenly emerging from a roadside parking bay.
  • Weaving from one wheel track to the other also draws attention. It may look erratic and as though you have lost control, but it attracts much-needed attention.
  • Never assume a driver has seen you.
  • Assume they haven’t seen you and prepare an exit route in case they drive out in front of you or merge into your lane.
  • Don’t ride in a vehicle’s blind spot.
  • Give yourself a buffer  zone from other vehicles.
  • Slow down and get ready to take evasive action if you see a vehicle at an intersection.
  • Wait until you see the whites of their eyes before accelerating. And even then, prepare for them to make a sudden move.
  • If so, it is best to think about changing course behind the car, rather than in front of it. The normal reaction is to weave away from the direction that the threat is coming. However, that leads you into the direction the threat is heading, so you may still collide.
  • If you don’t see the whites of their eyes, then it might be time to give a polite toot on the horn to alert them.

Riders tend to think SMIDSY collisions occur because motorists don’t care about motorcyclists.

That’s not necessarily true. Even if they don’t care about us as people, they still care about getting their car damaged.

Consequently, several car manufacturers are working on various blind-spot alerts that specifically recognise motorcycles. They even include an alert that taps a driver on the shoulder if they move into a lane occupied by a motorcycle.

Maybe they should also include wing mirrors with “look twice” messages like those in the photo at the top of this article.

You can read about those technologies, tips on being more visible and other SMIDSY collisions in the articles listed below.


  1. “Maybe they should also include wing mirrors with “look twice” messages like those in the photo at the top of this article.”
    Good point Mark, However the, the ever increasing average of drivers that can not read, for example, keep left unless overtaking, give way, stop, etc etc etc, kinda blows that out of the water.

    Yeh I know.
    Cynical Grumpy Old Bastard. :-p

    Ride Free, Ride Safe everyone.

  2. My 2c on the visibility thing.

    We all multitask, with the brain doing things in the background and more important things get a higher level of consciousness.

    I doubt that any experienced driver/rider has ever devoted 100% of their highest level of consciousness to driving/riding 100% of the time. We think about the journey purpose, destination, work and/or family issues, etc whilst still operating the vehicle. The brain does auto switching of conscious level need based on some form of sub conscious background risk assessment. Who in their cage has never got somewhere, and then wondered to themselves what happened in the last few kms/miles? Did you obey the posted limit, run a light etc? Its gone from your shorterm memory, but you somehow successfully did it. A disproportionate number of incidents occur when drivers are close to home. Why? Likely thinking about what happens next when they arrive, not the there and then. Currently in a familiar environment, so subconscious risk based decision says to focus on the destination and subsequent events, not the now. Why do, in Oz at least, 80% fatal car crashes occur on straight roads? Sub conscious risk assessment again, brain says its OK to play with a/c, kids, food, phone etc as situation not complex, then….

    Motorcycles don’t normally present a threat to drivers, like a truck or police vehicle, or outlaw biker might, so driver’s brain ignores our presence when its background processing the driving, as it does for cyclists. Then when we suddenly appear, near miss or otherwise, we must have been speeding, as we weren’t there a moment ago, when they think they looked. And if we were speeding it must have been our fault, not theirs.

    Lights on and hivis makes no difference in this situation, as we are not high enough up the food chain for it to matter to far too many operators.

    Looking twice might force the conscious level to rise a level. Assume everyone out there is daydreaming on their phone, texting about something really important, until proven otherwise.

  3. Another thing I’ve learnt: DO NOT overtake a car turning left into a side road. If you do it right (wrong, that is) you will be completely hidden from traffic turning out of that side road.


  4. “Time to arrival illusion” has been known for quite some time. It’s not really a SMIDSY though – because it’s a reason for drivers failing to properly account for a bike in their driving decisions.

    It’s good to have even more supporting evidence for it though because some influential folk doubt its veracity.

    Sadly it’s not the only cognitive failing that results in SMIDSY’s and SMIDSY like events. The list of actions in the article are good defensive steps for a rider to take, but the “disease” is better treated by driver awareness. Friends and family of riders report seeing more bikes on the roads when their loved one takes it up – all that has changed is their awareness and their brain no longer filtering out previously unimportant information. Even MUARC has research supporting this (but from a slightly different angle – I.e. Safety in numbers). Filtering is one way to slowly chip away at the awareness deficit in the road going community. A targeted ongoing series of television PSA’s would be better.

  5. There was an article in one of the papers I read probably the Brisbane Times on what’s called inattential blindness. It occurs mostly with people at a lower mental processing ability level but not necessarily dumb but can even happen to the best of us when we are starting to suffer mental fatigue, what happens is the brain starts to take shortcuts filtering out almost all information but what we are thinking about at the time. There is a famous visual example of this used to train law enforcement and security personnel, in the video a group of people are playing basketball and the trainees are asked to observe what happens, almost all note the number of baskets and by who but they all fail to mention the guy in the gorilla suit who strolls past the court.
    How does this apply to drivers? It seem that when they look to see what’s coming before making a turn or changing lanes they’re predominantly looking for cars because that is what is mostly on the roads, trucks only register to them because they pose a threat that registers with their subconscious enough to almost always realise the danger, but not always there have been incidents of people pulling out in front of fire trucks with lights and sirens going because they didn’t see them even though they looked the driver in the eyes.
    So when fire trucks don’t exist for these people what chance does a biker have?

  6. I read an interesting article about motion camouflage, where as the approaching object is hidden by the fact it maintains a straight steady course. The suggestion was to weave from side to side to break that illusion of the object appearing to not be moving forward.

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