With the rapid development of China's economy, the scale of road traffic continues to expand, and the number of tunnels has also increased. In addition to providing a comfortable lighting environment for the driver, the highway tunnel lighting system also saves operating expenses. At present, highways generally lack energy-saving control systems. Therefore, providing lighting functions while reducing tunnel operating expenses is an important issue in the research and construction of tunnel lighting systems. Realizing highway tunnel lighting energy-saving control has important practical significance for energy-saving and emission reduction.
Highway traffic is expanding with its own scale with economic development and social progress. In recent years, with the continuous advancement of construction technology and the increasingly mature survey and design concepts, China's highway tunnel construction has also reached a new level. According to incomplete statistics, in the past ten years, the total length of highway bridge tunnel ferries has reached 5,122,551 meters, and there are as many as 7,384 tunnels, 4,444 short tunnels, 1,357 medium tunnels, 1218 long tunnels, and extra-long tunnels. 265 (as shown in Figure 1). Among them, the Qinling Zhongnanshan Highway Tunnel has a length of 18.02 kilometers and is known as “the first in Asiaâ€.
Figure 1 Statistics on the mileage of highway tunnel ferries in China in the past ten years
According to the above data, road tunnels have become an important facility for fast, safe and high-speed transportation in China, and as a core measure to achieve environmentally friendly traffic, it plays an indispensable role in the development and progress of modern transportation in China.
Development status of highway tunnel lighting system at home and abroad
1.1 Status of foreign development
As early as the 1950s, the research on highway tunnel lighting technology was carried out abroad, and it has been more than 60 years. After continuous exploration and innovation in many countries, the highway tunnel lighting technology is quite mature. When time develops into modern times, tunnel lighting systems in developed countries are gradually developing from high-tech intelligence to sustainable humanization. In Eastern European countries alone, highway tunnels have generally begun to use "secondary light distribution" and "backlighting" technologies. While making full use of the light source, resources such as electric energy and lighting tools are saved. In the choice of lighting tools, developed countries such as Europe and the United States abandoned high-pressure sodium lamps and switched to new types of equipment such as optical fiber tunnel lights and electronic induction lamps.
1.2 Status of domestic development
The development of domestic tunnel lighting system started late. Although the current development of highway tunnels in China is very rapid, it still cannot match the mature technology and concept of foreign countries. The gap is not only manifested in technology and experience, but also in basic engineering construction. In January 2000, China promulgated the "Code for Design of Ventilation Lighting for Highway Tunnels", which detailed the dimming classification of tunnels, the classification of light sources, the total uniformity and the layout of lamps. However, due to the extremely serious waste of power resources in recent years, relevant departments have begun to pay close attention to the energy-saving design of tunnel lighting systems. While studying the theory in depth, China has also applied corresponding energy-saving design in the construction of expressway tunnels. For example, Guangdong Longtoushan Tunnel, Hebei Simatai Tunnel, Anhui Qianjiashan Tunnel, etc. have successively applied LED lights and stepless dimming technology. Highway tunnel lighting.
1.3 Development trend of highway tunnel lighting
The quality of highway tunnel lighting affects driving safety. For many years, highway tunnel builders have always regarded lighting quality as the core content and research focus of engineering design, but have neglected the problem of energy waste. Therefore, under the premise of ensuring driving safety in China, the design of highway tunnel lighting system is an inevitable requirement for the development of highway tunnel lighting system. Humanization, economy and scientificization are the inevitable development of lighting technology and social development. trend.
Highway tunnel lighting system design
2.1 Characteristics of highway tunnel lighting system
The highway is generally a semi-enclosed space, and the interior of the space is composed of a special tubular structure. This kind of design is likely to cause the traffic environment inside and outside the tunnel to be too different, which causes the light and dark alternate when the vehicle passes through the tunnel, which affects the driving vision. Therefore, based on the premise of tunnel safety and operating environment comfort, the highway tunnel design process needs to consider factors that affect lighting quality, such as flickering, uniform brightness, visual effects, and road surface brightness. According to the regulations of the International Commission on Illumination, the highway tunnel needs to take into account the driver's dark adaptation and adaptability in the design process. Therefore, the tunnel illumination can be divided into five parts: the approach section, the entrance section, the transition section, the intermediate section, and the exit section. as shown in picture 2:
Figure 2 Tunnel segmentation diagram
2.2 Energy-saving design requirements for highway tunnel lighting systems
2.2.1 Approach segment design. The approaching section acts as a section of the road close to the tunnel entrance and serves primarily as a preliminary mediation of the driver's vision. The brightness close to the segment space is close to the brightness outside the hole, so there is no need to set the illumination. Under normal circumstances, a large number of trees will be planted on both sides of the roadbed or light-reducing measures such as louver canopy and broken wall openings will be built. The design is designed to reduce the "black hole" effect and save energy.
2.2.2 Design of the entrance section. The first section of the entrance of the expressway tunnel is the entrance section. The design of the section is designed to eliminate the influence of the "black hole" effect on the driver, avoid traffic accidents, and play a certain advantage.
Energy saving. Calculate the brightness according to the K-value calculation method according to the "Code for Design of Ventilation and Lighting for Road Tunnels", namely: Lth=L20(S)·K
2.2.3 Transition section design. After the vehicle passes through the entrance section, the tunnel illumination brightness will gradually drop to the middle section illumination level. In this process, the area where the illumination is dimmed is called the transition section. The transition section lighting is designed to help the driver adapt to lower brightness and overcome the "adaptation lag" effect.
According to the "Code for Design of Ventilation Lighting for Road Tunnels", the transition section has three sections TR1, TR2 and TR3. The length of the transition section is calculated according to the maximum speed of the tunnel design and is calculated according to the CIE adaptation curve function, namely:
Ltr=Lth*(1.9+t)1.4
2.2.4 Intermediate section design. The longest section of the expressway tunnel is the middle section. After the driver passes the previous three sections of road, the driver has fully adapted to the degree of illumination inside the tunnel, so the middle section lighting is the basic lighting. The Design Code for Ventilation and Lighting of Highway Tunnels stipulates that the minimum brightness requirement for the middle section of the expressway tunnel is 2.5 cd/m2. Under normal circumstances, the middle section lighting brightness design can be based on the design of Table 1.
2.2.5 Design of the exit section. As the last section of the expressway tunnel, the exit section has a shorter adaptation time through the section, so the lighting design of the exit section should be based on eliminating the “white hole†effect. According to the relevant provisions of the "Code for Design of Ventilation Lighting for Road Tunnels", the brightness of the exit section should be 5 times the brightness of the middle section and the length should be 60m.
Design of Energy Saving Control System for Expressway Tunnel
3.1 main program design
The core of the highway tunnel energy-saving control system is to provide on-demand lighting for vehicles, and based on this, to achieve energy-saving control of highway tunnel lighting system. The specific process is as follows: the main program is started and the power-on self-test is performed, the component failure is eliminated, and the system initialization is started when the system is running normally; when the system is abnormal, the system is first repaired and the main program is exited. After the energy-saving control system completes the self-test and initialization process, it can start normal operation. The main program will predict the vehicle's driving speed through the pulse signal, and use the data cloud to simulate the vehicle position to ensure that the system error is controlled within 1%. The corrected vehicle position is used as the starting area to start lighting adjustment. The specific process is shown in Figure 3:
Figure 3 Main flow chart of highway tunnel lighting energy-saving control system
3.2 Vehicle position cloud simulation system calculation
The cloud simulation system is the core part of the energy-saving program for controlling the highway tunnel lighting system. The program system transmits the collected vehicle position information to the DSP, and after the vehicle position estimation program completes the data processing, it is sent to the relay input terminal by TMS320F/28035. To complete the lighting control. The specific process of the vehicle position estimation program for the highway tunnel lighting energy-saving control system is shown in Figure 4.
Figure 4 Flow chart of vehicle position estimation program
3.3 Highway Tunnel Lighting Control Program Design
The system uses the relay control as the control core, and sends the corresponding action control lighting fixtures through the position data of the vehicle collected by the front end of the system after being processed by the DSP. When the received control signal output is low, the relay will open, otherwise the relay will pull.
Conclusion
With the rapid development of China's economy, the number of expressway tunnels is increasing. Most modern tunnel lighting systems have shortcomings such as energy waste and ineffective lighting. Because of these reasons, the waste of tunnel operation expenses has increased. In this paper, a targeted analysis of the waste of high-speed tunnel lighting system resources and the development of corresponding strategies provide a powerful guarantee for reducing tunnel operating costs and improving the efficiency of lighting systems. While meeting the basic lighting needs of the expressway tunnel, it ensures that the tunnel provides the necessary lighting according to the actual situation of the vehicle, thus achieving the purpose of energy saving, consumption reduction and efficiency improvement.
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