THE PERISCOPE OPERATED BY LIGHT——introduce light into the tunnel
Daylight investigations - Region 4: Asia and Oceania
Beijing University of Civil Engineering and Architecture
RESEARCH BACKGROUND“Black hole effect” is a more common phenomenon in daily traffic, namely, when the car drove up to a long tunnel portal in the drivers vision, open in the sky of the road, nearby buildings, such as the brightness of the object, far higher than the brightness of the tunnel portal, make drivers feel the mouth of the cave was very dark, like a “black hole”, so that couldn’t make the hole inside the case, even the obstacles are hard to find, This phenomenon is called the “black hole effect”.At present, the main measures taken to improve the “black hole effect” in highway tunnel are to strengthen the lighting at the entrance section of the tunnel, to set up reflectors on both sides of the tunnel wall, to set up light-reducing sunshades and luminescent coatings at the entrance of the tunnel, but these methods have high investment and daily operation costs.Visual adaptation refers to the changes in the sensitivity of human eyeballs to external illumination stimuli. The human eye has a certain self-regulation ability, as the light changes, the pupil of the human eye will make corresponding changes.As the depth of the tunnel increases, the illumination changes to different degrees, especially at 20 m before and after the tunnel entrance. The illumination at the tunnel entrance is about 70% of the illumination outside the tunnel, but at 20 m inside the tunnel, the illumination is only about 2% of the illumination outside the tunnel.When the vehicle enters the tunnel at a speed exceeding the design speed of 5km/h, the visual oscillation phenomenon will occur. When the vehicle enters the tunnel at a speed exceeding 20km/h, the visual oscillation phenomenon will be very obvious, making it difficult for the driver to see the road condition ahead clearlyDESIGN SPECIFICATIONBased on the “black hole effect of tunnels, it is important to reduce the visual impact on rivers entering and leaving the tunnel, to reduce the possibility of car accidents, and to reduce the economic cost of installing artificial light.our design is to set up a “light device” outside the tunnel to change the direction of natural light through multiple reflections and lead it to the tunnel entrance. At the connection between the device and the tunnel entrance, a light source conversion device based on optical fiber is set up to introduce light energy into the tunnel interior through the optical fiber, changing the light brightness with the depth distance, and reasonably connecting the artificial light source inside the tunnel to reduce the change of light and dark vision during the driving process. At the same time, using the principle of optical fiber, the light inside the tunnel is given different colors to increase the visual aesthetics while lighting and reduce the driver’s driving fatigue on the highway.ln order to make the device more efficient and practical, the periphery of the device can be placed as daily traffic signs and reflectors to remind drivers. During the daytime, the device brings natural light into the tunnel and transforms it into a lighting device. At night, using the bi-directional nature of the optical fiber, the light source from the artificial lighting inside the tunnel can be returned to the original path, turning the device into nighttime highway lighting and realizing multiple uses of one device. PERISCOPE PRINCIPLESubmarine periscope, using the reflection of light, is used to observe at the bottom of the sea using a periscope that can probe out of the water.The designed device uses the periscope principle to transmit light to the optical fiber at the tunnel entrance after multiple reflections through the internal channels of the device, thereby transmitting the light into the tunnel for illumination.ln order to make the most efficient use of natural light, openings are made in three directions of the device to meet the incidence of sunlight at different angles, and the high-efficiency reflective panels in the channel are used for multi-angle reflection.Reflect natural light through the device into the tunnel during the day, and reflect artificial light through the device to the tunnel entrance at night, as a warning and lighting function on the company highway.