Safe Speed Forums

The March issue of Bike magazine contains an interesting article on SMIDSY type accidents. To summarise: it has been suggested that when an object is moving towards you such that it doesn’t move against its background, the object either blends into the background or appears to be stationary. However as the object gets very close it’s size appears to rapidly increase, the “looming effect”. This is because looming works on the part of the visual cortex that use “edge detection”. If no edges are detected no alert is triggered. This might explain why car drivers pull out, and then stop suddenly as they freeze when the bike looms into view. The majority of accidents result in the bike hitting the car just behind the A pillar.

Extending this theory (probably unjustified I know) to vehicle speed. At lower speeds, 40-50mph the bike blends into the background, at high speeds say 60-80mph the fact that bike is travelling faster across the background will in itself create an edge effect that the car driver can detect. This could also apply when looking directly at an approaching vehicle. If it’s travelling fast, the fact that it does appear to get larger as it approaches will also generate an edge effect.

To avoid motion camouflage the suggestion is for bikes to move from one side to the other of their lane to create an edge effect against the background.

Oh Good!

I'm delighted that that stuff has finally been published. I was talking to the originator many months ago and put him in touch with Bike. He asked me to keep it confidential until published.

He's certainly got some interesting ideas which can lead directly to practical SMIDSY avoidance strategies that bikers can use. There's a large dose of plausibility in the view and I'm quite certain it happens on occasion.

My only real reservation is that (as a car driver) it's never happened to me. What's the explanation for that then?

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

???????

Wot hasn't?

Not seeing someone?

But how can you know!

_________________
http://www.itsyourduty.org.uk

Not knocking the researcher, but why have we got to the stage where we need research to tell us the bleedin' obvious?

Surely we all know that if something isn't (or, more importantly, doesn't appear to be) moving: we don't "see" it (or sense it).

Which is why we don't notice a watch or our underwear after we put them on.

And why big cats stay motionless for long periods when stalking other apes.

We automatically switch off to unchanging stimuli to avoid information overload which could lead to missing something important.

Unfortunately that defence mechanism sometimes backfires.

_________________
http://www.itsyourduty.org.uk

I think you have missed the point - the bike is moving obviously, however the car drivers perceives that it isn't even though the bike is coming towards them at speed. Only at the last minute do they register the fact as the looming effect takes over, by that time it is too late.



Sorry but I don't think it is bleeding obvious! In some cases it is possible that the "T-bone" accident involving a bike and a car is caused by this.

See http://www.dcs.qmul.ac.uk/~aja/motion_cam.html[/b]

This is certainly a well known phenomenon within the field of aircraft accident investigation. To one pilot the approach of another aircraft can appear to be a speck on his canopy or quarterlight, the effect can last for quite a few seconds. At literally the last second the stationary speck looms large and takes form... unfortuantely by this time a collision is usually unavoidable.

IMO the research is not to tell Us the bleedin obvious, but to tell the powers that be where the nose is on the front of their face.

_________________
Semper in excreta, nur quantitat variat.

..

Oh, right. That's interesting. It was new to me and I assumed...

Always dodgy to assume...

Any theories about why I've never experienced the effect as a driver? That's the bit I can't get my head around.

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

..

It's possible, although stereo vision runs out at about 60 feet. I wouldn't think stereo vision would help much in the faster out-of-town situations.

I'm tempted to believe that I've learned a visual search strategy that reduces, mitigates or even eliminates the risk.

Has anyone profiled smidsy involved drivers? Are they usually less experienced?

If there is a visual search strategy, it might have something to do with the "double look", but then again it's rare for my second look to reveal any surprises, so I'll guess wildly that that can't be the answer.

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

I think that some SMIDSYs aren't SMIDSYs at all - its something we've covered on numerous occasions on visordown (survival skills) section.

the reality is that some drivers will find it easy to say (having catapulted the rider through the air) that they didn't see him or that he came from nowhere.

basically it sounds better than.

I thought he'd stop
I thought I could make it.
I didn't look
I don't care
I was in a rush.

The motorcyclists defense is to use what I refer to as the herding principle as it is unsafe to simply slow down if you believe you are at risk from a SMIDSY.

Slowing down will likely increase the risk from the rear and may imply that you are giving way to the other vehicle.

Moving out and away helps alert their vision - sideways movement being eisier to spot that something coming directly towards you.

Says - I'm not stopping - stay there to the driver (herding)

gives you space and therefore time to react.

Paul. I'd say its because you actually take care to look properly, and have trained yourself to actually SEE what is there. I'm sure you've covered this on the site somewhere but drivers generally don't 'train' their brains to see bikes. Its nothing to do with what the eyes see, but how the brain interprets it. I meen, on an open road in a car I will generally spot a bike sooner than I would have spotted a car in the same situation, because as a biker I've trained myself to look out for other bikes.

Also I do think that alot of it comes down to what diy said - car drivers either missjudge a bike's speed / distance (which is partly down to background camouflage and the narrow front profile of most bikes) or just assume that it can get out of the way.

I've had one or two near miss SMIDSY's that I've managed to avoid by either altering my road position or speeding up / slowing down accordingly, but then again I watch any vehicle waiting to imerge or turn infront of me like a hawk.

_________________
Science won over religion when they started installing lightning rods on churches.