Street lamps are intended to illuminate the road. and traffic routes in both urban and rural areas to reduce accidentsand increase safety for those traveling on the road Providing light to cover the entire road or area that needs to be used is therefore important. Because the right amount of light helps to see things correctly. If the light distribution pattern is not good Too much light can cause accidents on the road.

In considering the form of light distribution of street lamps, two forms are considered.

1.1 Vertical Light Distribution

          In considering the light distribution pattern of street lamps This model considers the distance from the street lamp in the direction parallel to the length of the road in order to know that each street lamp has the ability to cover a period of light. how many times of the street lamp installation height along the length of the road (TRL), which can divide the light distribution range into periods according to the table.

          (Luminance Eng.ne er.ns Society of North America) is the main consideration of the luminous intensity distribution. On the road surface is a type that illuminates the front (Lateral Light Distributions herein called distribution type or type) and opposite each side of the street lamp position (Vertical Light D.strib tons, herein called Distribution range is divided into distribution types (Type) II, III and IV, which characterize the light distribution in front across the road, while providing a shorter distribution range (S; Short), medium (M; Medium) and long (L; Long) are indicators at the luminous intensity point. in the designated area By the distance on the road surface compared to the height of the street lamp, IESNA sets the criteria for classification. Street lamps are listed in the table below.