Research On Performance And Evaluation Of Road Lighting Changes With Haze And Fog

With the continuous spread of haze and fog in more and more cities, road lighting safety is facing more serious challenge. O n the one hand, haze reduces the road visibility and the ability of color discrimination of people. O n the other hand, haze makes the average road surface illuminance no longer meet the safety requirements, which causes paralyzed traffic and frequently traffic accidents. In order to ensure the good light environment and the safety of road lighting, this article studies the effects of haze and fog on road lighting photometric characteristics, with three different color temperature LED street lamps and a traditional high pressure sodium lamp. According to test results, this paper analyses the impact of haze on the road lighting photometric characteristics, and proposes a highly individualized intelligent lighting control system. The full contents of this paper are as follows:Firstly, under the actual night haze and fog weather condition, the photometric characteristics of three different color temperature LED street lamps and a high pressure sodium lamp are detected. Under different concentrations of haze and fog, illumination and color index are measured at each lamp’s lighting centre. The experime nta l results show that w it h the increase of the concentratio n of the haze and fog, both the LED street la mp and high pressure sodium la mp have different degrees of reduct io n of illuminat ion. The maximum variation rate of illumination of three LED street lamps is all under 3%, while the high pressure sodium lamp is above 10%. For the illumination transmittance, it is reduced in heavy haze and fog. LED with low color temperature has higher illumination transmittance in light degree of haze and fog, while in heavy haze and fog, the regulation is on the contrary. LED street lamps’ color index basically does not change with the haze and fog, by contrast, the high pressure sodium lamp has an obvious increase.Secondly, using the MES2 model recommended by CIE, the experimental data of illumination mentioned above which is under photopic vision is converted into illumination under mesoptic vision. By calculating the illumination transmittance under mesoptic vision, this paper aims to analyze each lamp’s change trend, and compare their differences.Lastly, this paper builds an intelligent lighting control system under the influence of haze and fog. Setting the inverse of the illumination transmittance calculated above as an impact factor, and each impact factor is corresponding to an index of haze. For any index of haze, changing standard power of the lamp to be measured, and making the value of new power equal to standard power multiplied by the impact factor corresponding to the current index of haze. In this way, the illuminance returns to normal level, and meet the requirements of road lighting again.