Kind of already happening. Many gps units warn you if you're over the speed limit, and limits are set with upcoming curves factored in.

> Kind of already happening. Many gps units warn you if you're over the speed limit, and limits are set with upcoming curves factored in.

Here's a startup idea, but not for the faint of heart:

1. The authorities put a QR code (http://en.wikipedia.org/wiki/QR_code) on all the speed-limit signs, a label that can be read from a great distance, and one specially coded to be unambiguously a speed limit notification.

2. An enterprising startup designs an Android app that (a) reads QR codes through the windshield of a car, (b) compares the speed limit to the GPS-derived velocity, and (c) alerts the driver that he's exceeding the locally posted limit.

3. Drivers plant their Android devices on the dashboard of their car and run the app. The dashboard of a modern car happens to be a great place to get a GPS fix.

This isn't meant to force people to drive the speed limit, but only to let them know when they aren't.

Current cars (BMW, Mercedes-Benz) already have that. There's a camera that recognizes signs and warns you if you're above the limit. See http://www.bmw.com/com/en/newvehicles/3series/sedan/2011/sho...

Oh, well, this won't be the first time I have suggested something that's already been done. :)

I think this kind of technology is already being placed inside cars themselves. And the QR code is probably harder to scan while moving than recognising the speed limit plate itself.

The problem with this is that if you rely on the system and there is an error in the map (the curve is not marked) you have a big problem. If you don't rely on the data and drive carefully there is no point anymore :) A possible solution would be to detect the curve radius with a camera, but it has it's own problems. You never have 100% accurate data.

Well the market is for careful drivers who once in a while aren't paying attention, or are simply approaching a curve that isn't well marked.

I'd consider it a system of last resort, not something to replace careful driving but to enhance it.

And maybe throw in some modifiers if it's raining (or has recently rained) and if it's dark or foggy.