Research Of Average Luminance And Overall Uniformity Of Luminance Of Overpass Lighting In Urban

Since 1928,the United States built the world's first overpass has been nearly a hundred years time,overpass in urban traffic occupies an increasingly important position,and also become a symbol of a modern city.With the rapid development of urbanization in China,the number of overpasses increased dramatically and the construction technology became more and more perfect.However,in the field of lighting,overpass as a key area of urban transport,did not get enough attention.Domestic and international overpass lighting on the relevant norms are still incompleted.Now the domestic overpass lighting design is based on the general road indicators,or on the designer's experience.The lack of uniform quantitative standards,resulting in different status of domestic overpass lighting,gives rise to the problem that the lighting is too bright or too dark.In this paper,the basic indicators of overpass lighting research methods have been given,as well as the suggested values of the average luminance and the overall uniformity of luminance.It is of great significance to the standard of overpass lighting,increasing the safety of traffic at night on the overpass,as well as to reducing the economic losses caused by traffic accidents.Based on the site investigation of partial overpasses in 7 major cities in China,this paper summarizes the basic data and lighting status of the overpasses.Based on the analysis of the driver 's visual characteristics and needs,combined with the corresponding standards of the urban road design and engineering specifications,the three dimensional dimensions of the overpasses were screened and set,and the lumination representative model for the night traffic of the overpass was deduced.Based on the study of visibility model of small target visibility and road visibility theory,the visibility model of overpass lighting was constructed based on typical model of overpass lighting carrier.And the corresponding parameters of the digital model in the laboratory were set up according to the relevant contents of the visual basic theory.The scene simulation of the overpass lighting was made with the DIALux software and the POV-Ray plug-in.The control method of luminance and uniformity in the laboratory was obtained through field test,and the corresponding parameters were set by using graphic processing software such as Adobe Illustrator.According to the road lighting visibility theory,the average luminance and overall uniforamity of luminance index of the overpass lighting were evaluated by a large number of subjective evaluation experiments.Through the evaluation system for the definition of small target visibility,anti-introduction to meet the suggested value of average luminance and overall uniformity of luminance,which would satify the visual requirements for the driving of the overpass at night.