With the continuous development of society, the demand for road is also more and more primary, because the journey is a kind of capital that is always relatively scarce, a lot of time request demand for distance is also very high, we in order to reasonable allocation and effective use of the capital, so is the traffic laws and regulations, there are traffic lights, signs and other equipment is to collaborate to safe, reasonable, fair and efficient allocation of the capital.

Original of the two paths, but there are moments, they have the necessary cross, so, the original occupy two road traffic, in here, it is necessary to share the stacked road area, or redistribute the strip away all the capital at the intersection. So-called crossroads, some is stacked two road, here, assume that does not do particularly plan - such as broadening, grade separation, set up call to vomit inverse the and so on, the original two of their respective accounts for 100% of cars on the roads, here even just 50%.

Assumes that the car is less, namely that capital is not very scarce, big car arrived here in some of the night, and will not meet other car also should pass, distribution rule, it is not so first, look at don't have a car before, namely, the wild road is so remote village.

Assumes that the car more, for example, a car came here, often encounter other cars are coming, this time assuming no reasonable allocation rules, there will be two or more car preempted the situation of the capital, will cause the traffic issue, not only reduce the passage of power, will endanger the safety.

Very good approach is to set up traffic light, red light in the direction of the vehicle to stop waiting, and direction of the green vehicle direct traffic, don't have to slow down or even stop, traffic power will intersection is much higher than a parking sign, traffic power close to 100%. Problem is the brake needs time, you don't know when the red light, wait to stop at the red light, car would probably stop at the intersection base, other vehicles, this is the most taboo, because already intersection traffic capital scarce local, vehicle in this area the shorter the holding time is an appointment, to try to adhere to the intersection zone clear this is the advantage of traffic lights.

In fact many at the traffic lights for our help is in the very great degree is greatly reduced the occurrence of the traffic disturbance frequency, the maximum guarantee our personal and industrial safety, so for the setting of traffic light is still very necessary.