"Well, what was that all about then?" You're driving along on the motorway. There's plenty of cars on the road, but you're doing OK. Then all of a sudden the whole lot grinds to a halt. Probably roadworks or an accident you think. Then as if by magic you're off again and back up to speed, but there's no sign of whatever it was that caused the hold-up. What's going on? Well it turns out it is just shock waves moving back through the traffic: shock waves caused by nothing more than too many cars on the road. The same shock waves can also cause accidents if cars are too close together for the speed at which they are travelling. But what do they look like, and how do they arise? That is what the Traffic Simulator here aims to show, via simple visual means. Using this program you can now ...   - Watch shock waves of bunched and static traffic move back through a traffic line.   - Ride in a car and experience what the driver sees   - See how traffic speed cameras can CAUSE accidents!   - Fiddle with braking distances and cause multi-car pile-ups   - Marvel at just why anyone would write this stuff Technical Disclaimer: - The program is fairly computation-intensive for Javascript (which isn't really designed as a programming language). As a result it usually causes the browser to hang for a few seconds. This looks bad, but is OK and it soon comes back to life. In terms of browsers it only works in Internet Explorer 5+ or the excellent Opera (v6+ or maybe v5) - sorry Netscape users (all 6 of you), you'll have to go without. I really don't have the time or interest to do multi-browser versions anymore. No idea what'll happen on Macs either.