Them how to use the right?

Them the correct method of use:

1, on normal roads, failure or an accident, should set them in the car after 50 meters to 100 meters.

2, on the highway, to 150 metres after the car set up warning signs;

3, if meets the fog had, had to distance the ascent to 200 meters. In the process of concrete use, when the accident need emergency stop on the way, should place them in the rear or with a driveway, not on the suitability, otherwise not only does the warning role, is also likely to mislead the rear car to judgment, are more likely to increase the probability of secondary accidents.