Imagine a traffic accident on a highway, how can you warn drivers miles away to slow down? The answer lies in the Variable Message Display (VMS), a portable LED screen device that displays real-time traffic information such as “Slow Down” and “Road Closed”, with the core function of improving traffic safety and optimizing traffic efficiency by delivering timely information, especially during emergency situations. Its core function is to enhance traffic safety and optimize traffic efficiency through timely delivery of information, especially in unexpected scenarios to quickly guide the traffic flow. Among the many types of VMS, truck-mounted VMS and trailer-mounted VMS are the more mobile ones. In this article, we will break down their advantages, applicable scenarios and actual performance to help you find the most suitable traffic management tool.
When you are driving on a highway, you may have noticed this kind of facilities — large LED screens will display “slow down”, “no passing” and “speed limit” in real time. “Slow Down”, “No Traffic”, “Speed Limit 60km/h” and other traffic alerts are displayed in real time on large LED screens. These electronic LED devices, which dynamically display a variety of special messages, are called variable message signs.
As an electronic device used to convey important information, the core of variable message signs is a large LED display. It can present graphics, text, and symbols, and is often mounted on portable trailers, stands, or vehicles that can be flexibly moved to different locations as needed.
Fixed VMS: These signs are also called permanent variable message signs and are usually fixed to utility poles, gantries and other facilities on highways, ordinary roads or in urban areas.
Truck-Mounted VMS: It is installed on trucks, vans and other transportation vehicles, with strong mobility, and can be transported to various designated locations according to actual needs.
VMS Trailer: This is a portable device with signs mounted on a trailer that can be towed and moved by other vehicles. It has a wide range of applications and can be quickly deployed to a variety of locations.
Truck-Mounted VMS
The high mounting position of the Truck-Mounted VMS is a significant advantage – the screen is located on top of the truck, and this height allows the driver to see the information from a greater distance, especially on the highway, where a few seconds of advance warning gives the driver more time to react. Even in dense traffic, the high position reduces the probability of being obscured by other vehicles and ensures that information is delivered effectively.
At the same time, it integrates multiple safety designs, adopting high-brightness LED screen, which can maintain a clear display in direct sunlight during the daytime or in dark environment at night; part of the equipment is equipped with flashing light or strobe light, which can quickly attract the attention of the driver to strengthen the warning effect of emergency information, such as “Accident Ahead”. In addition, the truck’s own safety features (e.g., lane departure warning, blind spot monitoring) can also reduce the risk of accidents during operation.
Mobility is another highlight of truck-based VMS. It can arrive at the scene quickly in the event of an emergency (e.g. traffic accident, temporary road closure). For example, after a multi-vehicle collision, the truck-mounted VMS can immediately drive to the upstream section of the road and display the real-time display of “Accident ahead, please slow down and change lanes”, helping to divert traffic and reduce the occurrence of secondary accidents.
The stability of the Trailer-Mounted VMS comes from its design – it can be secured by anchoring devices (e.g., stabilizer feet, counterweight base) when deployed, and remains stable even in environments such as strong winds and complex terrain. This stability is especially important in scenarios such as construction zones where constant alerting is required, avoiding interruptions in message delivery due to equipment movement.
Once deployed, the trailer VMS is virtually immune to the risk of accidental movement. It is not dependent on a tow vehicle, eliminating the need for displacement due to vehicle vibration, uneven terrain or unexpected weather. At busy intersections or construction zones, the fixed position allows drivers to form a stable information expectation and enhance the alerting effect.
In addition, it is ideal for long-term unattended use. Equipped with a durable LED screen and a solar/battery powered system, the message remains clear and stable even when left outdoors for weeks or even months. This feature reduces the need for frequent maintenance, which ensures consistent messaging and lowers long-term operating costs.
VMS tailer
The stability of a truck-mounted VMS depends entirely on where the truck is parked. Only when it is parked on a flat surface and properly secured can the screen be guaranteed to be stable; if it encounters uneven terrain, it may sway slightly, affecting the stability of the information display.
In extreme environments, its shortcomings will be more obvious. The high screen is easily affected by wind in strong windy weather, and may be shaken or even tilted at risk; frequent movement will also aggravate the wear and tear of the equipment — long-term driving on bumpy roads, the screen fixing structure, the circuit system and so on, may be aging in advance, and require more frequent overhaul and maintenance. Therefore, it is more suitable for short-term use and is not recommended for projects lasting several months.
The Performance of Trailer VMS is designed for rugged use and offers significant stability advantages. It comes with its own anchoring devices (e.g. retractable stabilizer feet, weighted base), which are secured when deployed and “rooted” firmly to the ground, even in strong winds or minor terrain ups and downs.
In terms of durability, its structure is more adapted to long-term outdoor use. The shell is made of wind, rain and corrosion-resistant materials, which can withstand the erosion of rain, snow, ultraviolet rays and other natural factors; the solar power supply system reduces the dependence on external power sources, and as long as there is light, it can replenish the power to ensure that the equipment continues to operate. As a result, it can work stably for months unattended, making it ideal for long-term projects.
VMS tailer
Truck-mounted VMS can be used for “dynamic following” in event / race guidance scenarios. For example, during a marathon race, it can move along the track, displaying real-time information such as “1km to the finish line” to participants, and alerting the surrounding vehicles that “the race is ahead, please slow down and avoid” to make up for the limited coverage of the fixed screen.
In emergency rescue, its mobility is irreplaceable. When the rescue fleet departs, the truck-mounted VMS can drive to the road ahead in advance, displaying “the ambulance is about to pass, please yield to the right” to open up a channel for the rescue vehicles; after arriving at the scene of the accident, it can also be used as a temporary command point to deliver to the surrounding area “the accident is being processed, please detour! After arriving at the accident scene, it can also be used as a temporary command point to deliver the message of “Accident processing, please detour” to the surrounding area to reduce the congestion caused by the gathering of onlookers.
In high-speed emergency command, the trailer-mounted VMS can play a quick role. After a high-speed accident, it can be quickly towed upstream to the accident point, and the 360° rotating screen ensures that drivers in all lanes see messages such as “Accident ahead, speed limit 40” and “Please detour in the right emergency lane. The solid structure allows it to remain stable in traffic alongside the highway, continuing to deliver information until the accident has been dealt with.
In construction zone warning scenarios, it is a long-term reliable “safety guard”. Road maintenance, bridge construction, and other projects often last weeks or months, and a trailer-mounted VMS can be stationed at the entrance to a construction zone, continuously displaying messages such as “Construction Ahead, Speed Limit 20,” and “Please Drive on the Left. The solar-powered system eliminates the need for frequent wiring or refueling, and can operate stably even in remote construction sites, effectively alerting passing vehicles to avoid accidents and reducing the risk of accidents in construction zones.
Truck-mounted VMS takes “flexible mobility” as its core competitiveness and is suitable for short-term emergency and dynamic guidance scenarios, while trailer-mounted VMS takes “stability and durability” as its core advantage and is suitable for long-term stationary and continuous alerting scenarios. When choosing, you don’t need to dwell on which one is “more advanced”, but focus on your core needs — do you need to be “on standby like a mobile sentry” or “to be on permanent duty like a fixed post”. If your traffic management needs balance short-term and long-term scenarios, consider a combination of the two as well — use a truck-mounted VMS for emergencies and a trailer-mounted VMS to cover long-term projects, making traffic management more efficient and safer.
