This is not a rant about speed limits. They may be annoying, but they have their uses and I generally try to keep to them. This is a rant about how all the effort goes into catching those driving too fast and nothing to help the driver keep to the limit.
Well perhaps there are exceptions. I have driven cars that can be set to a maximum speed and then emit a discreet beep when that speed is exceeded. That's good. That's the sort of thing I want. It keeps you in control, you can go as fast as you like if you accept the consequences, or, as happens sometimes, to get out of trouble on an ill-timed overtake. But it doesn't go far enough. It's good for long motorway stretches where it's all the same limit, but it's not those that usually catch me out.
It is no longer possible to reliably tell the speed limit from the type of road, there are so many exceptions. The A420 for example, between Oxford and Swindon, is constantly changing between 50 and 60 mi/h with no obvious change in the road; if you can't remember the last sign you passed miles ago you have to look out for the infrequent and sometimes overgrown repeaters. There's another catch on a 3-lane dual-carriageway near Northampton which has a short 60 mi/h section surrounded by 70. It's there because of lanes joining and leaving, but the attention given to that makes it easy to miss the limit signs, which when it's busy and you're in the middle lane you can only see on the overhead signs.
The first requirement for the law-abiding motorist to keep to the limit is to know what the limit is at all times. There should be an immediate indication of the limit whenever it is not the default limit for the type of road. For example a coloured line at the edge of the road, or numbers painted on the road every 100 metres. Or even repeater signs as now, but at short intervals, not every half-mile or so.
But that's only the first part. If the government can be considering a nationwide vehicle-tracking network for road pricing, then a much simpler system could provide an in-car indication of the current limit and an optional indication of exceeding.
That would be the ideal. It would make it possible to keep to speed limits and avoid picking up penalty points without having to apply a considerable part of one's attention remembering the limit and constantly checking the speedometer.