Method for measuring brightness outside highway tunnel

Abstract

The invention discloses a method for measuring brightness outside a highway tunnel. The method includes the steps that A, the relation between brightness values of scenes outside the highway tunnel and the illumination value of the horizontal plane is determined, and a brightness meter and an illuminometer are used at the position away from a tunnel portal by a safe stopping sight distance for reading at the same time and obtaining brightness values L of scenes of the tunnel portal and the illumination value of the horizontal plane E; B, the computation standard value of brightness of the scenes outside the highway tunnel is determined, and the hourly total illumination and scattering illumination of regions in a typical meteorological year are obtained through radiation observational data and radiation light equivalent models of the regions; C, the area percentage of the scenes outside the highway tunnel within the view field of the cone angle of 20 degrees is determined, and the border line of the view field of the cone angle of 20 degrees of a driver at the position away from the tunnel portal by a stopping sight distance is drawn out on each picture of the tunnel portal; D, the value L20 (S) of brightness outside the highway tunnel is determined according to an environmental diagram method. The method is easy to implement, easy and convenient in operation, accurate and reliable in measurement result, and capable of being widely applied to measuring the brightness outside existing highway tunnels.

Description

technical field [0001] The invention belongs to the technical field of road tunnel lighting, and more specifically relates to a method for measuring the brightness outside a road tunnel. Background technique [0002] The "black hole effect" formed by the sharp brightness, space, and transition of reference objects at the entrance of the highway tunnel makes it difficult for drivers to adapt to the vision, and it is easy to form a blind period of vision, which in turn induces traffic accidents such as rear-end collisions and collisions with tunnel doors. Therefore, enhanced lighting is generally installed at the entrance of the tunnel to alleviate the "black hole effect" and ensure the safety and comfort of driving at the entrance of the highway tunnel. Luminance L outside the highway tunnel 20 (S) is an important basis for the design of the enhanced lighting system at the entrance of the tunnel. It is of great significance to reasonably determine the brightness outside the ...

AI Technical Summary

Problems solved by technology

The look-up table method is to determine the L 20 (S), although this method is simple, but because the brightness of the sky at different locations varies greatly, and the reflectivity of different objects outside the cave also varies greatly, so the error of the look-up table method is very large

The blackness method takes black-and-white photos facing the entrance of the tunnel at a height of 1.5m from the beginning of the tunnel’s approaching section. The blackness of each scene within the 20° cone angle field of view is read on the instrument, and the average blackness is calculated by weight, and then the brightness L outside the tunnel is determined. 20 (S), but its use has strict restrictions on time and weather, that is, in summer (June, July, August) when it is sunny and cloudless, it will be carried out for 3 consecutive days, and it will be measured and read 5 times a day (11:00 to 15:00 hour, time interval 1h) or 11 times (8:00 to 18:00, time interval 1h)

The environmental sketch method is to determine the L according to the brightness of various scenes within the 20° cone angle field of view and the percentage of their area. 20 (S), compared with the blackness method, the environmental diagram method omits the process of camera optical characteristic calibration, but if the brightness of the scene recommended by the relevant specifications is used, it cannot adapt to the diversity of geographical locations; and if the brightness of the scene is actually measured, However, there are still problems of strictly limited measurement conditions and complicated parameter calibration.

[0005] Existing brightness measurement methods outside the highway tunnel mostly use general specifications to calibrate the brightness parameters of the scene, resulting in poor applicability and difficulty in meeting actual needs; or using conventional measurement methods, but the test conditions are strictly limited and need to be carried out in summer When the sky is strictly cloud-free

The applicability and practicability of existing road tunnel brightness measurement methods are poor, and it is difficult to meet the actual needs of road tunnel entrance lighting system design. Therefore, a measurement method for road tunnel brightness is urgently needed

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