Road facilities that convey guidance, restriction, warning or indication information through words or symbols. Also known as road signs and road traffic signs. Setting eye-catching, clear and bright traffic signs is an important measure to implement traffic management and ensure safe and smooth road traffic. In ancient Rome, there were milestones and signboards on the military avenue from Rome to Gapuya. In the 3rd century, China used bronze watches in Wei Wendi. However, before cars were widely used, there were not many kinds and quantities of road signs. With the increase of the number of cars and the development of highway traffic, the types and quantities of traffic signs are increasing gradually, but all countries adopt their own designed signs. 1908, at the first international road congress held in Paris, the topic of unifying traffic signs was put forward, but no agreement was reached. Later, many conferences were held in Europe, America and Africa to discuss the unification of regional or global traffic signs. From 65438 to 0968, the United Nations promulgated the Agreement on Road Traffic and Road Signs and Signals, which served as the basis for countries to formulate traffic signs. Since then, traffic signs in various countries have gradually developed in the direction of international unity in terms of classification, modeling, color and design. There are many kinds of traffic signs, which can be divided into: main signs and auxiliary signs; Movable signs and fixed signs; Lighting signs, luminous signs and reflective signs; And variable information signs that reflect the change of driving environment [edit this paragraph] The main signs and auxiliary signs can be divided into four types. (1) indicator; Usually round and rectangular, with white patterns on a blue background. Used to instruct vehicles and pedestrians to drive in the specified direction and place. Such as going straight, turning left, turning right, stopping, bypassing, etc. ② Warning signs: generally equilateral triangle (or diamond), yellow (white) background with black (red) edge, and black (or dark blue) pattern. It is used to warn drivers to pay attention to the dangers of the road ahead and the measures that must be taken. For example, predict intersections, road turns, railway crossings, slippery sections, possible rockfall sections, uneven roads, combined traffic, etc. ③ Prohibition sign: generally round, with white background and red edge, black pattern and red diagonal line. It is a sign that vehicles are prohibited or appropriately restricted according to the situation of streets, highways and traffic flow. Such as no traffic, no parking, speed limit, weight limit, width limit, etc. ④ Guiding signs: generally rectangular, with white characters on blue (green) background. Used to indicate the boundaries between towns and villages, the direction and distance of destinations, the entrances and exits of expressway, service areas and places of interest. And all kinds of guidance along the way. For example, national highway numbers, milestones, 100-meter piles, boundary markers, signboards, and signboards at expressway entrances and exits, gas stations, repair stations, parking lots, etc. The auxiliary sign is attached to the main sign and plays an auxiliary role. It can be divided into four categories: vehicle type, time, interval range and distance. Auxiliary signs cannot be set separately. Auxiliary signs are attached to the main signs and play an auxiliary role, which are divided into time, vehicle type, area or distance, warning, prohibition reasons and other types. [Edit this paragraph] Movable signs and fixed signs Movable signs are generally used in temporary construction sites and can be taken away after use. Fixed signs are permanent signs, which are divided into single column, double column, cantilever type, portal type and attached type (installed on other structures) according to structural forms. Signs are usually placed where drivers can easily see them. Some signs need a certain advance distance, that is, there is time to take necessary actions after seeing the signs. The height from the lower edge of the sign installed on the roadside to the road surface is generally 120 ~ 250 cm, and the height of portal and cantilever signs should meet the clearance requirements, generally greater than 450 cm. [Edit this paragraph] There are three lighting methods for lighting signs, luminous signs and reflective signs: ① Internal lighting, which uses the light source behind the sign panel to illuminate the sign pattern or bottom plate through translucent materials; (2) External lighting: install special lamps to evenly illuminate the sign panel; (3) Other equipment, such as making logo patterns with plastic LEDs. Luminous signs are generally made of fluorescent materials. The reflective film of reflective sign is made of transparent resin (including adhesive), glass beads, reflective metal and other materials, or glass beads are pressed into plastic. When car headlights shoots at the reflective sign, the reflective film can directionally reflect the light back, so that the driver can see the sign clearly at night. Reflective brightness, chromaticity, weather resistance, adhesion, tensile strength, solvent resistance and other properties of the reflective film should meet the requirements. [Edit this paragraph] Variable information signs The driving environment on expressway may change due to weather (such as fog, snow, rainstorm and icing), natural disasters (such as earthquake, flood, typhoon and landslide) and traffic accidents. The variable information sign can inform the driver of the change of driving environment in time. Various information is stored on the variable information sign, and the controller can display some information manually or automatically through the remote control device according to the situation on the expressway. There are three ways to change information: ① The choice of background color is to show the degree of traffic congestion in expressway and ground streets and the degree of traffic delay on the adjusted ramp through the display of different background colors on the road map. The light leakage sign adopts the background color selection method. When the background color is black (dull), the information does not appear, and when the background color is white (light), the information appears. The background color can be selected by electronic switch or mechanical method. Selecting background color with electronic switch is a selection method controlled by circuit. This is a mechanical selection method, and the background color is selected by an electric color filter turntable. (2) Information panel selection is to select a content to be displayed from several information panels by mechanical method. It can be divided into: scrolling panel selection, that is, storing some information (such as bus destination signs) on a flexible and transparent roller; The choice of rotating panel is to draw three kinds of information on the three panels of rotating Mitsubishi column; Reversible panel selection is to store information on both sides of the flat panel, and the flat panel can be turned over. (3) Character format selection, the most commonly used is the light bulb matrix logo, which uses the method of circuit control to make the light bulbs specified in the matrix glow and form various characters. It can also be selected by mechanical method, that is, a magnetic matrix assembly composed of many small metal disks is adopted. After receiving the pulse signal with correct polarity, the position of the small metal plates will be reversed, and the front of each small metal plate is a luminous reflective surface, and the back is a dark background color, thus forming various characters. Optical fiber light guide sign is a new energy-saving sign. As a reflective medium, optical fiber makes the light shine on the small light bulb at the other end of the fiber through internal reflection, which can form any required characters. If a filter is added between the light source and the optical fiber system, color characters can be displayed. [Edit this paragraph] Provisions on the color and shape of the sign (1) The color of the warning sign is black pattern with yellow background and black edge, and the shape is an equilateral triangle with the top angle upward. Note that the colors of the pedestrian vector traffic warning signs (2) prohibition sign are white background, red circle, red bar and black pattern, and the pattern is suppressed. Among them, the sign of lifting the prohibition of overtaking and speed limit is a black bar with a black circle on a white background and a black pattern. The shape is round, and the giving way sign is an equilateral triangle with the vertex down. (3) The color of indicator is blue background and white pattern. Shapes are round, rectangular and square. (4) Except for milestones, 100-meter piles and highway jiepai, the color of road signs is generally blue and white. Except for the location identification signs, the shapes are all rectangular and square. Milestones, 100-meter piles and road boundary piles are all guiding signs. When the milestone is located on the national highway, the colors are white and red; When set on the dart, the color is white and blue; When it is located on the county highway, the color is white and black. Regardless of the nature of the road, the color of highway boundary markers is white and black. The auxiliary sign is a sign attached to the main sign and plays an auxiliary role. Points indicate time, vehicle type, area or distance, warning, reasons for prohibition, etc. [Edit this paragraph] The position of warning signs set by various signs is related to the calculation speed of expressway. In rural mountainous areas, highways should generally be located 20 ~ 50 meters away from dangerous places. No parking signs should generally be set where restrictions or prohibitions are needed. In addition to no parking signs, the starting and ending points of restricted or prohibited sections and both ends of the bridge should be set in pairs. Indicating signs are mostly used in urban roads and high-grade highways, and are rarely used in general highways. Directional signs are commonly used signs in expressway, such as place names, boundaries, directions, milestones, 100m stakes and expressway boundary stakes. Place name signs are located on the edge of the town; The boundary sign is located at the boundary between the administrative division and the supervision area; Direction signs are set 30 ~ 50 meters away from the intersection. [Edit this paragraph] Logo setting mode and related regulations (1) column type (including single column type and double column type); (2) cantilever type; (3) portal type; (4) Attached type. According to relevant regulations, the distance between the inner edge of column sign and the road surface (or shoulder) shall not be less than 25 cm, and the height between the lower edge of the sign and the road surface shall be 180 ~ 250 cm. The height between the lower edge of the cantilever sign and the road surface, the clear height of the first and second grade roads is 5 meters, and the clear height of the third and fourth grade roads is 4.5 meters. The distance between the inner edge of the column and the road surface (or shoulder) shall not be less than 25cm. Traffic signs will develop in the direction of symbolization, unification, prominence, energy saving and light weight, and the research on new materials, new structures and new energy-saving signs such as solar signs, laser signs and holographic signs is being paid attention to.