Google self driving car: What they consider?

Google pioneer in internet services launch a dream project with its success in preliminary stage. Google proposed a dream of driverless car or self driving car project, that many people thought its juts a dream, how they can do it? its impossible, but putting the efforts by team Google in edge cutting research for behavior of vehicle and other agents that shares road, like other vehicles with manual driving, pedestrians, cyclists, traffic signals, railway crossings etc.
Look at later post  How Google self driving car programmed?? with animation video.

Google's Lexus Rx 450 car (Photo: wiki)

How is it possible to run a car just through the programming on it? may be this question rounding in your mind. Here  i wanna try to explain.

Firstly it uses the high accuracy navigation system which has all information of road, including lanes, junctions, intersections, curves information so any one can start to run from one point then it automatically follow the shortest route possible to get there. Hence routing is quite easy that now a days many companies provide such navigation system but just for information to driver. Google had coupled this navigation system in programming so it direct on steering movement.

What happen if some vehicles stop suddenly on the way? No problem for that, it has the system of sensors so it can read any object that is near with it few meters in side and many in front. If it found some object moving slower than it or stopped then it will try to overtake that if possible having care with other vehicles in another lane otherwise it will stop or slow what ever it needs according to sensor.