Re: [SystemSafety] How Many Miles of Driving Would It Take to Demonstrate Autonomous Vehicle Reliability?

From: Peter Bernard Ladkin < >
Date: Sat, 23 Apr 2016 19:37:29 +0200

On 2016-04-23 17:43 , Martyn Thomas wrote:
> To illustrate what I mean with just one, very small, example,

For me, a very important situation. I think Martyn's reasoning about it is absolutely right.

> cyclists might get used to AVs passing
> them with a wider clearance than is the normal behaviour of human drivers. (This /should/ happen
> because the code of acceptable driving - called the /Highway Code/ in the UK, for instance - sets a
> standard that many drivers currently forget or ignore).

Yes. In Germany too.

The clearance on German roads is defined in the law as 2m. But I think there are "boundary cases"; clearance becomes enforced when there is an accident and a question about it, and I think under 1.5m is regarded by most or all courts as too little when an accident has ensued and compensation is negotiated. There is currently underway an advertising/informational campaign in Bielefeld to make drivers leave 1.5m clearance when overtaking a cyclist.

Personally, I experience that somewhere over half the overtaking vehicles do not leave 1.5m clearance. You might think this is hard to judge; it's not, because it can be done indirectly, as follows.

I ride 70cm-1m from the road edge (recommended best practice), my bike is 33cm wider than its track at the handlebar tip (52cm if you count the mirror, which many people don't). So I am there occupying 1m-1.3m of the highway left of the road edge (right-hand drive, remember). It follows that the right side of an overtaking vehicle must be 2.5m-2.8m from the road edge to conform. Cars are 1.6m (Mini) to 1.8m (suburban assault vehicle) wide. That makes the highway breadth taken up for overtaking a bicycle 4.1m-4.6m.

The roads I use which I have to share with motorised vehicles (i.e., no separate bike lane) are around or even under 6m wide. A driver really has to be well on the other side of the road (left/driver's side typically 1m-1.5m from the opposite road edge) to leave the required 1.5m. Most overtaking vehicles are nowhere near that.

Interestingly, the regs say that the breadth of the highway to allow car-bicycle passage must be 3.25m. That's for same-direction traffic as well as opposite-direction traffic. That suggests the road designers think it's OK to have 3.25m, whereas the calculations above yielded 4.1m-4.6m for this manoeuvre, which is roughly a meter more.

PBL Prof. Peter Bernard Ladkin, Faculty of Technology, University of Bielefeld, 33594 Bielefeld, Germany Je suis Charlie
Tel+msg +49 (0)521 880 7319

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