Traffic Law Enforcement and Driver Perception of Safety

[John the Monkey]

Interesting piece of research referenced on Tom Vanderbilt's blog today;

http://www.howwedrive.com/2008/11/10/how-drivers-decide/

The crux of it is that in the particular study referred to, how traffic law was enforced (in this case the speed at which drivers felt exceeding speed limits would result in them receiving a ticket) directly affected their perception of how safe it was to travel at particular speeds.

“So the faster you think you can go before getting a ticket, the more likely you are to think safety’s not compromised at higher speeds,” said Fred Mannering, a professor of civil engineering at Purdue University, in Science Daily.

Has some interesting implications for other traffic law, imo.

 

[MartinC]

Interesting. Reinforces, for me, the idea that more rigorous enforcement of traffic law (or even enforcment!) would have a beneficial effect on road safety. If only we could make the establishment (police, CPS, courts) more receptive to this idea.

 

[Tony]

I note that the petrolhead fora all seem to cover the same ground, viz the tolerance for speeding, 10% plus 3 mph. So speed limits are treated as raised, a 30 becoming a 36, for example. We then see their whining when someone is done for 37. "It was only 1mph..."

 

[mickle]

I reckon the widespread use of SatNavs has raised average speeds. Car speedo's are in the region of 10% out. If I (were to) use the SatNav speedo in a 50 mph zone and add ten percent for the enforcement cameras margin of error giving me 55 mph my car speedo reads 60 mph.

Which also means of course that the mugs who receive speeding tickets must have been going many mph faster than that displayed on their car speedo.

 

[CopperBrompton]

Speedos used to over-read by about 10% years ago, because it was illegal for them to under-read and manufacturers couldn't be confident in the accuracy of mechanical speedos. They thus played safe by making them over-read.

Any speedo on a modern car is electronic, not mechanical, and should be much more accurate than 10%. On my 7-year-old car, for example, it's within 1mph up to 40mph, 2mph up to 70mph and still within 4mph at 140mph.

 

[mickle]

My Corrado is about 10% out but.

 

[cheadle hulme]

My Skoda Fabia speedo has the same size increments for each 10mph, up to 90mph. Then the next increment is 110mph, 130mph for the same size increment.

Most people have no idea of the (non linear) relationship between speed and impact energy, hence the usual comments about 35/40 being OK in 30 zones.

 

[Tony]

Yup. Energy increases as the square of the velocity. But then, the speeophile "professional engineer" and his successors were never very numerate