First need to assess qualification of manufacturer.
Concentration of traffic signal manufacturer in Jiangsu, Shandong and Jiangxi, the real qualification and the size of the factory will not be more than 30. So, buy traffic lights can be found from these places.
In terms of quality, and Jiangsu and Zhejiang provinces, in addition to several older traffic signals manufacturer are excellent, but ranks should be in front of Yang manufacturers, especially the lamps at the same time export manufacturers.
After the information is gathered from manufacturers, we can do the job is in the local manufacturers to find the enterprise's registration information, know whether the signal is a professional manufacturers.