Rick Tait, R.Tait@bnr.co.uk, reports Marcus Reynold's note that there's a new

...

speed trap in Kent. Apparently the radar clocks your speed, a TV camera records your number plate & then a real time OCR system picks out the actual number & flashes it up on a digital display a short distance further up the road. [...] The ability to read a car's plate & decypher the number in real time without any human intervention must take a bit of work.

There's a lot of automated-highway research going on; most of it has been oriented towards radio+smartcards, which are easy to make accurate, and while they're not totally cheap, you can palm off much of the cost on the car-owner and use cheap equipment in the tollbooth. License-plate reading in real time is tough, if you're trying to get both speed and accuracy from a video image of a moving car; our neural-net folks were looking into it about three years ago, and it seemed like they'd be pretty good at it if they could get a bit more funding:-) ; they've mainly been concentrating on envelope-readers for Post Offices and railroad-car identifiers. Embarrassing speeders is a special case, because the accuracy doesn't really have to be 100% - you catch the cars on video, so if you decide to prosecute anybody, you can have a human read the picture and verify that you had the right license plate number. Meanwhile, back on the road, if your computer misidentifies the speeding driver half the time, he may assume the speed trap was nicking the other fast car next to him, and you've scared a lot of other drivers into slowing down because it *looks* like you've could have nicked them; so you've accomplished the safety objective. It's scary stuff, because the technology is mostly there, and a government that wanted to pay for development could get it done by a number of research companies. If it's too expensive for widespread use now, computer horsepower keeps getting cheaper every year, especially when what you need is DSP-crunchers and gate-arrays for neural nets, rather than general-purpose systems. Meanwhile, the smartcard people are mostly not using digicash, they're using no-privacy systems and appealing to the convenience for the commercial driver, whose company probably doesn't object. Dave Mandl comments:

Hmmm...most drivers I've known would be thrilled to get off with just "embarrassment." In fact, they'd probably be proud to have it broadcast to everyone else on the road (except the lawmen, naturally) that they'd just been clocked at 110 MPH or whatever.

A number of years ago, Ohio tried a system that displayed your speed (but not your license plate) as you went by - they quickly discovered that they had to cut off the display at something like 80 or 85 MPH to prevent just that effect (though adding the license plate number would cut down on the exhibitionism a bit.) Bill Stewart