[Closed] traffic simulator ideas?

Hi guys,

I am trying to write a traffic simulator and I found this russian site with an awesome one but unfortunately is not for sale. Here is a link to their page:
http://www.xn–d1abb4ane.com/blog/archives/77/76

Any ideas how to achieve something similar? Now here are my main problems:

1. How to make cars slow down and accelerate based on street signs
2. Changing lanes
3. Avoiding collision with other cars

For changing lanes I have an idea based on path constraints as you can have multiple paths affecting the object and you can change the path weight. But for the other issues I am still in the dark…