Road Weather Stations & Road Sensors
Definitive Guide -2019
Including Visibility Sensors | Road surface sensors | Pavement Sensors
Including Visibility Sensors | Road surface sensors | Pavement Sensors
Safety of transportation are closely related to weather.
With the rapid development of transportation, traffic safety accidents are frequent, which brings huge losses to people’s lives and property.
Meteorological influence is one of the main causes of traffic accidents.
According to statistics from the traffic department, nearly 30% of traffic accidents occur under bad weather conditions.
Such as low visibility, heavy fog, ice, water, snow, high temperature, strong wind, dust storm, drought, frost, etc.
Heavy rainstorms Secondary geological disasters such as floods, mudslides, and landslides are major catastrophic weather that affects traffic safety.
Strong wind, hail and other strong convective weather can also have a greater impact on traffic, the wind can cause serious damage to buildings, traffic facilities, and so on.
When the motor vehicle is overturned by the wind, the ability of the car to drive in the wind and the ability to catch the tires is obviously weakened.
According to the theory of wind pressure, the square of the wind speed is proportional to the wind area. When the body-wide side is subjected to wind, the force is the largest.
The wind speed is above 12m/s, the steering wheel is easy to malfunction and should slow down slowly.
The critical wind speed of the highway accident is often 15m/s, the corresponding gust can reach 22m/s.
If it is accompanied by rain, the car is more difficult to control.
The wind can cause harm to the railway, bridge, communication and electric power facilities, blow down the road tree, block the traffic, wind up the roadbed, and blow the sand to reduce the visibility.
The wind can also directly harm the train so that the speed of the train is slowed down and the train is even overturned.
The influence of wind on the water traffic is especially obvious, especially in the open area of water.
The ship is not too late to enter the shelter area and often causes the ships to be blown by the wind and so on.
Hail can also cause damage to motor vehicles and road traffic facilities, but often hail has a smaller range, short impact time and less influence on traffic than other weather phenomena.
Thunderstorms also threaten the safety of transportation facilities, bridges and so on.
The phenomenon of frost and snow caused by low temperature directly affects the friction coefficient of pavement.
Road icing and snow will greatly reduce the friction coefficient of the road, and the safe braking distance of the vehicle will also increase correspondingly.
Due to the rapid cooling of the bridge or the draught section, the road is easy to freeze. It is easy to cause traffic accidents when the motor vehicle passes through these roads on the normal road.
Snow, avalanche, snow and other snow damage to railway traffic is also very important, visibility reduced, driving speed, train late, and even cause subversion of the train.
Low temperature caused by frozen rivers also directly affect water transport.
|Wind Direction||Measuring range 0~360°|
Accuracy ± 3°
|Ultrasonic anemometer, maintenance free|
|Wind Speed||Measuring range 0~60 m/s|
Accuracy ：± 0,3m/s or ±3%
|Ultrasonic anemometer, maintenance free|
|Temperature||Measuring range -50～85°C|
|Relative Humidity||Measuring range 0～100%|
|Air Pressure||Measuring range 300～1200 hpa|
Accuracy ±0.3 hpa
|Rain||Optical scattering theory|
Accuracy using the highest value: 0.001mm
|Optical principle, maintenance free|
Low Road visibility is the main meteorological disaster that affects traffic. Road visibility has a direct impact on traffic safety, especially on highway traffic safety.
The low road visibility weather often causes the congestion and sealing of the highway, which leads to the interruption of traffic and transportation.
Due to the networking of highways, the closure of some highways often leads to traffic jams and even traffic failures on other roads or small towns.
In addition, serious traffic accidents caused by low road visibility are more shocking.
According to statistics, traffic accidents caused by the influence of heavy fog on the expressway account for about 1/4 of the total number of accidents, and the accident rate of freeway in fog is 10 times as high as usual.
Therefore, the “thick fog” is the “killer” of the expressway.
Because of the impact of low visibility on highway safety and direct economic benefits, the consequential loss of economic benefits and bad social impact will be more serious.
Fog, precipitation (rain and snow, etc.), air humidity, air dust and smoke are the key factors affecting visibility.
Dense fog reduces horizontal visibility, the general visibility is less than 1km, or even less than 200m.
For trains, trains will have 800m gliding distances from braking to stop, so it is very easy to have accidents in the fog without slowing down.
Low road visibility has a great impact on water transportation.
When visibility is less than 1500m, ships will be affected and many ports are forced to do so.
Here is a road sensor: visibility sensor to monitor road visibility.
|Measuring range||5m～10km / 5m-30Km / 5m-50Km|
|Accuracy||≤2km Residual ±2% ; 2Km～10km Residual ±5%|
|Data Update Interval||15s、60s|
|Scattering Angle cover||39°～51° Forward scatter|
|Power Consumption||Less than 5W, typical value 4W|
|Dimension（L*W*H）||610mm x 230mm x 300mm|
|Weight||Less than 10Kg|
|Material||Hard aluminum anodized, outer surface spray paint protection|
|Temperature：-40°C to +85C|
At low temperature and rainy weather, the ground is slippery and easy to freeze, which will cause a huge safety hazard to traffic, and a non-contact surface condition road sensor can be used to monitor the road information in real time.
Here is a road sensor: non-invasive sensor to monitor road status.
|Measuring Diameter||25.4 cm|
|Maximum Power Consumption||4W|
|Operating Temperature||-40 ºC — +70 ºC|
|Operating Humidity||0 – 100%|
|Road State Output||Water：0.00—2mm|
|Lens Pollution Detection||Optical lens pollution level measurement and internal automatic pollution compensation|
|Roadbed||Concrete pavement and asphalt pavement|
|Safety||No safety issues – infrared remote sensing measurement technology|
AC power supply system, this way can effectively guarantee the quality of power supply and charging, and it can provide output for some sensor equipments that need AC power supply.
The DC power supply based on solar power supply is mainly designed for the inconvenient areas, such as unmanned areas, cities, pastures, and isolated islands, which provide communication.
The advantage of the solar power supply is that it can greatly reduce the damage caused by the induced current caused by lightning to the acquisition system and the sensor, and can reduce the incident caused by the inadvertent personnel.
Mainly through solar energy through the special solar charger to control the battery charging.
Note: in rainy areas, solar and battery capacity should be increased, and colloid batteries should be used in high and cold areas.
The main consideration is to use the cable Lan network or optical fiber to carry out data transmission.
If the site does not have the wiring environment, GPRS or CDMA wireless communication can be used, without the need for the construction of hardware facilities, but the problem of effective coverage of the GPRS or CDMA communication signals should be considered.
An intelligent communication server is used in the traffic weather information monitoring station.
It can realize the GPRS, SMS and GSM intelligent complementary communication. It can achieve high reliable data transmission and two-way communication.
At the same time, it realizes the monitoring and maintenance of the remote sub station. Through the combination of GPRS, SMS and GSM, we can achieve two-way reliable communication between the central station and the observation stations.
The intelligent communication server is a wireless communication transmission based on INTERNET, which realizes real-time data, timing data, system information, test signal and so on.
It can be monitored and maintained through the weather information monitoring center station.
The wireless communication unit adopts the world’s advanced industrial GSM module, built in TCP/IP protocol, supports GPRS, GSM, SMS and so on.
It has the characteristics of high integration, strong function, low power consumption and strong anti-interference ability.
The highway weather disaster prediction and early warning center is a software processing system.
It mainly includes the functions of meteorological data collection, data processing and storage, weather information browsing, early warning information release control, substation state monitoring and remote maintenance.
It can extend the application monitoring function of other ground detection system, the data application analysis module developed by users, and get first-hand weather information data.
In order to provide better traffic weather services, the system design fully considers the local climate characteristics and the meteorological requirements, and takes full consideration of the future development.
The software architecture combined C/S and B/S structure, based on the GIS geographic information system, is used to build a complete set of comprehensive Expressway meteorological monitoring system.
The layout of expressway traffic and weather monitoring network in these areas is mainly caused by low visibility fog. The basic layout principle is:
First, for a plain or hilly area, when considering fog disaster, the density of meteorological observation stations can be divided into three categories.
The distance between observation stations is 20 to 50Km in dense fog area.
The distance between observation stations in seasonal heavy fog area is 10 ~ 15Km.
The distance between observation stations in mountainous area and water network area is 3 to 5Km.
Second, for areas with complex terrain such as high mountain terrain, the density setting of the observation station should mainly consider the key points and the regional range that one observation point may represent.
The setting density of the traffic meteorological observation station should be treated with similar methods when considering other meteorological elements.
In particular, the “local” characteristics of some meteorological disasters should be more obvious, and the setting density of the observation stations should be strengthened.
In the case of limited funds and conditions, priority should be placed in the high-risk sections such as fog. All monitoring stations should include visibility factor.
In high altitude, plateau and other desert areas, the layout of the observation network along the highway should take sand dust storm and wind as the main consideration. The basic layout principles are as follows:
The distance between monitoring stations is 20 ~ 30km in Sandstorm and windy areas.
The distance between monitoring stations is 30 ~ 100km in sandstorms and windy areas.
Easily caused by topography frequent sandstorms or local highway across regions, should be laid in the wind observation station encryption.
In the case of limited funds and conditions, priority should be placed in such areas as sandstorms and other severe weather. All monitoring stations should include visibility factors.
The layout of the meteorological observation network along the expressway is mainly based on the area, snow and freezing.
The basic layout principles are as follows:
In winter, the temperature of winter is lower than 0 centigrade and snowfall.
The monitoring station is designed to monitor the ground area snow, ground freezing and friction coefficient, and the distance is 30 ~ 50km.
When there is not much snow, but in winter, the main factor of monitoring is the road friction coefficient. The spacing between stations can be set to 50 to 80km.
The area where ice skid is easy to cause skidding can increase the number of equipment appropriately.
In the case of limited funds and conditions, priority should be placed in the frequent snowfall.
All monitoring stations should include ground condition elements, with emphasis on monitoring land surface temperature, precipitation property, area snow depth, friction coefficient and so on.
For areas such as mountain, valley, hilly and other special terrain as well as a variety of disaster weather, the main influencing factors are analyzed according to different terrain and climate background, and the automatic station with high influence factors is set up after determining the main monitoring indexes.
The layout of the density is based on the scale and scope of the influence of the disaster weather.
Some sites should include pavement condition monitoring, which are mainly installed on large bridges and overpasses through the expressway, and should also be installed in the key areas where the expressway is prone to high temperature and ice.
Pavement condition monitoring can choose sensors installed on monitoring road surface temperature or combination elements according to the local road surface temperature and ice occurrence.
The site layout of the road condition monitoring site is equipped with the density of the distance 30-50km, and the monitoring equipment should be added to the section of the large bridge, the elevated interchange and the local ice phenomenon.
A Road Weather Information System (RWIS) comprises automatic weather stations (technically referred to as Environmental Sensor Stations (ESS)) in the field, a communication system for data transfer, and central systems to collect field data from numerous ESS. These stations measure real-time atmospheric parameters, pavement conditions, water level conditions, and visibility. Central RWIS hardware and software are used to process observations from ESS to develop nowcasts or forecasts, and display or disseminate road weather information in a format that can be easily interpreted by a manager. RWIS data are used by road operators and maintainers to support decision making. Real-time RWIS data is also used by Automated Warning Systems(AWS). The spatial and temporal resolution can be that of a mesonet. The data is often considered proprietary although it is often ingested into numerical weather prediction models.
|What vendors make products that address the Road Weather Information System needs? Is there a critical path to deliver Road Weather Information System results?||Weather has broad and significant effects on the roadway environment. Snow, rain, fog, ice, freezing rain, and other weather conditions can impair the ability of drivers to operate their vehicles safely, significantly reduce roadway capacity, and dramatically increase travel times.|
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