Rubber hoses in the road approx 1m apart - what are they for?

We'll have to agree to differ, then. They measure speed by having two rubber strips a measured distance apart (see original title of this post, although the metre is unusually wide). The time delay between activating strip A and then strip B gives the speed of the vehicle. Successive vehicles are recorded over a long period by marking a paper strip. Very basic and cheap technology. A speed camera is quite expensive and needs to be set up on a suitable pole, involving staff who have been trained in the Working at Height Regulations (2005). I don't understand the relevance of how many axles the vehicle has. The second (and any subsequent) axle pass(es) can be ignored. So far as cars going in contrary directions are concerned: 30 mph is 44 feet per second, so the registration of the first car takes about 0.3 seconds. If you think that it is *commonplace* for a second car going the other way to register within the 0.3 seconds, I have to disagree with you. Of course it *could* happen, but it is exceedingly unusual. It would probably result in an impossibly high calculated speed, which obviously would be disregarded.