What are the special meanings of different colors and shapes of traffic warning signs?

road facilities that convey guidance, restriction, warning or indication information by 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 road traffic safety and smoothness. In ancient Rome, there were milestones and signboards on the military avenue from Rome to Gapuya. China used a bronze watch in Wei Wendi in the 3rd century. 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 transportation, the types and quantities of traffic signs are increasing gradually, but all countries adopt their own designed signs. In 198, at the first international road conference held in Paris, the topic of unifying traffic signs was raised, 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. In 1968, the United Nations announced the Agreement on Road Traffic and Road Signs and Signals as the basis for countries to formulate traffic signs. Since then, the traffic signs of various countries have gradually developed in the direction of international unity in terms of classification, shape, color and pattern. There are many types 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 a white pattern 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: usually 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 in the road ahead and the measures that must be taken. For example, forecast intersections, road turns, railway crossings, slippery sections, possible rockfall sections, uneven roads, combined traffic, etc. ③ Prohibition sign: usually round, with white background and red edge, and black pattern with red slash. It is a sign that vehicles are prohibited or appropriately restricted according to the situation of streets, highways and traffic volume. Such as no traffic, no parking, speed limit, weight limit, width limit, etc. ④ Guide signs: usually rectangular, with white characters and white patterns on a blue (green) background. It is used to indicate the boundaries of towns and villages, the direction and distance of destinations, the entrances and exits of expressways, service areas and famous places, etc., and carry out various guidance along the way. For example, national highway numbers, milestones, 1-meter piles, boundary markers, signboards, and signboards for highway entrances and exits, gas stations, repair stations, parking lots, etc. The auxiliary sign is attached to the main sign to play a supplementary role. It can be divided into four categories: vehicle type, time, interval range and distance. Auxiliary signs cannot be set up separately. Auxiliary signs are attached to the main signs, which play an auxiliary role, and are divided into types such as time, vehicle type, area or distance, warning, reasons for prohibition, etc. [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 single-column, double-column, cantilever, gantry and attached (installed on other structures) according to structural forms. Signs are usually placed where drivers can easily see them. Some signs require a certain lead 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 12 ~ 25 cm, and the height of the gantry and cantilever sign should meet the clearance requirements, generally more than 45 cm. [Edit this paragraph] There are three lighting modes 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, installation of special lights, evenly illuminate the sign panel; (3) other equipment, such as using plastic light-emitting tubes to make logo patterns. 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. The reflective brightness, chromaticity, weather resistance, adhesiveness, 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 the highway may change due to weather (such as fog, snow, rainstorm and icing), natural disasters (such as earthquake, flood, typhoon and landslide) and traffic accidents. Variable information signs can inform drivers of changes in driving environment in time. A variety of 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 highway. There are three ways to change the information: ① The selection of background color is to show the degree of traffic congestion on expressways and ground streets and the degree of traffic delay on adjusted ramps through the display of different background colors on the road map. The light-leaking sign adopts the background color selection method. When the background color is black (no light), 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 the background color with electronic switch is a selection method controlled by circuit. It is a mechanical selection method to select the background color with a motorized color filter turret. (2) information panel selection is to select a content to be displayed from several information panels by mechanical method. It can be divided into: rolling panel selection, which is to store some information on a flexible and transparent roller (such as the bus destination sign); The selection 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 circuit control method to make the light bulbs specified in the matrix emit light to 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 positions of the small metal disks will turn over, and the front of each small metal disk is a reflective surface that emits light, and the back is a dark background color, thus forming various characters. Fiber light guide sign is a new sign of saving energy. As a light reflection medium, the light guide fiber makes the light shine through internal reflection to the small bulb at the other end of the fiber, 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 yellow background, black edge and black pattern, the shape is equilateral triangle, and the vertex angle is 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 pressed. Among them, the signs for lifting overtaking prohibition and speed limit are white background, black circle, black bar, black pattern and pattern pressing bar. The shape is round, and the giving way sign is an equilateral triangle with downward vertex. (3) The color of the indicator is blue background and white pattern. The shapes are round, rectangular and square. (4) Except for milestones, 1-meter piles and highway jiepai, the colors of road signs are generally blue and white. Except for the location identification signs, the shapes are all rectangular and square. Milestones, 1-meter piles and highway boundary markers are all guiding signs. When the milestone is located on the national highway, the color is white and red; When it is set on the provincial road, the color is white and blue; When it is located on county and township roads, the colors are all white and black. Regardless of the nature of the road, the colors of highway boundary markers are all 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 calculated speed of the highway. In rural mountainous areas, highways should generally be located 2 ~ 5 meters away from dangerous places. No-stop signs should generally be set in places where restrictions or prohibitions are needed. Except no-stop signs, they should be set in pairs at the starting and ending points of restricted or prohibited sections and at both ends of the bridge. Indicating signs are mostly used in urban roads and high-grade highways, and are rarely used in general highways. Directional signs are commonly used in general highways, such as place names, boundaries, directions, milestones, 1-meter piles, and highway boundary markers. Place name signs are located at the edge of the town; The boundary sign is located at the boundary of administrative divisions and custody sections; The direction sign is set 3 ~ 5 meters away from the intersection. [Edit this paragraph] Logo setting mode and relevant provisions setting mode (1) Column type (including single column type and double column type); (2) cantilever type; (3) portal type; (4) Attached type. According to the relevant regulations, the inner edge of column sign shall not be less than 25 cm from the road surface (or shoulder), and the height of the lower edge of the sign from the road surface shall be 18 ~ 25 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 post and the road surface (or shoulder) shall not be less than 25cm. Traffic signs will develop into symbolization, unification, highlighting, 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.