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Variable-message sign
Variable-message sign
Variable-message sign
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LED matrix sign over I-94 in Saint Paul, Minnesota, advising of a road blockage during a winter storm
Early style of VMS on the New Jersey Turnpike using neon tubes, since replaced by new LED VMS signs. It is next to a vane variable speed-limit sign
Europe's largest Dynamic Route Guidance System Nuremberg, Germany
LED sign over I-90 (Jane Addams Memorial Tollway) in Riley Township, Illinois, showing remaining travel times
Mechanical variable-message sign (right) on the Prague Ringway, Czech Republic; made by Značky Praha s.r.o.

A variable- (also changeable-,[1] electronic-, or dynamic-) message sign or message board, often abbreviated VMS, VMB, CMS, or DMS, and in the UK known as a matrix sign,[2] is an electronic traffic sign often used on roadways to give travelers information about special events. Such signs warn of traffic congestion, accidents, incidents such as terrorist attacks, Amber/Silver/Blue Alerts, roadwork zones, or speed limits on a specific highway segment. In urban areas, VMS are used within parking guidance and information systems to guide drivers to available car parking spaces. They may also ask vehicles to take alternative routes, limit travel speed, warn of duration and location of the incidents, inform of the traffic conditions, or display general public safety messages.

History

[edit]

VMS systems were deployed at least as early as the 1950s on the New Jersey Turnpike.[3] The road's signs of that period, and up to around 2012, were capable of displaying a few messages in neon, all oriented around warning drivers to slow down: "REDUCE SPEED", followed by a warning of either construction, accident, congestion, ice, snow, or fog at a certain distance ahead.[4] The New Jersey Turnpike Authority replaced those signs (along with 1990s-vintage dot-matrix VMS systems along the Garden State Parkway) with more flexible electronic signs between 2010 and 2016.

The current VMS systems are largely deployed on freeways, trunk highways, or in work zones.[citation needed]

On the interchange of I-5 and SR 120 in San Joaquin County, California, an automated visibility and speed warning system was installed in 1996 to warn traffic of reduced visibility due to fog (where tule fog is a common problem in the winter), and of slow or stopped traffic.

Message Signs were deployed in Ontario during the 1990s and are now being upgraded on 400-series highways as well as two pilot secondary highways in northeastern Ontario.[5]

Technologies and types

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Early variable message signs included static signs with words that would illuminate (often using neon tubing) indicating the type of incident that occurred, or signs that used rotating prisms (trilons) to change the message being displayed. These were later replaced by dot matrix displays typically using eggcrate, fiber optic, or flip-disc technology, which were capable of displaying a much wider range of messages than earlier static variable message signs. Since the late 1990s, the most common technology used in new installations for variable message signs are LED displays. In recent years, some newer LED variable message signs have the ability to display colored text and graphics.

Dot-matrix variable message signs are divided into three subgroups: character matrix, row matrix, and full matrix. In a character matrix VMS, each character is given its own matrix with equal horizontal spacing between them, typically with two or three rows of characters. In a full matrix VMS, the entire sign is a single large dot matrix display, allowing the display of different fonts and graphics. A row matrix VMS is a hybrid of the two types, divided into two or three rows like a character matrix display, except each row is a single long dot matrix display instead of being split per character horizontally.

Overhead variable message signs are today available in three form factors: front access, rear access, and walk-in. In a front access variable message sign, maintenance is performed by lifting the sign open from the front. Most smaller VMS are of the front access form factor, and are typically installed today on major arterials. The rear access form factor is similar to the front access form factor, except that maintenance is performed from the rear of the sign, and are commonly used for medium-sized dynamic message signs installed along the roadside of freeways (instead of overhead). The walk-in form factor is a more recent introduction, where maintenance on the sign is performed from the inside of the sign. A key advantage of the walk-in form factor is that lane closures are generally not required to perform maintenance on the sign. Most of the largest VMS units installed today are walk-in units, and are typically installed overhead on freeways. [citation needed]

The NJ Turnpike Authority counts five unique types of variable message signs under its jurisdiction, at least one of which has been replaced by newer signs.[6] They are:

  1. "REDUCE SPEED" neon signs (1950s-2010, obsolete, have now been replaced).
  2. "Changeable message signs" (trilon/ rotating-drum signs that can be used for closing roads or moving traffic to other roadways).
  3. Electronic VMS: signs with remotely controlled messages displayed on them; the messages are sent from the State Traffic Management Center, updating the signs automatically.
  4. Variable speed limit signs - used for varying the posted speed limits within work zones and in emergencies.
  5. Portable VMS: movable "electronic VMS". A portable VMS has much the same characteristics as a fixed electronic VMS, but can be moved from location to location as the need dictates.

Usage

[edit]
Variable Message Sign
A variable-message sign.

Early models required an operator to be physically present when programming a message, whereas newer models may be reprogrammed remotely via a wired or wireless network or cellphone connection.[citation needed]

A complete message on a panel generally includes a problem statement indicating incident, roadwork, stalled vehicle etc.; a location statement indicating where the incident is located; an effect statement indicating lane closure, delay, etc. and an action statement giving suggestion what to do traffic conditions ahead. These signs are also used for Amber alert messages, and in some states, Silver and Blue Alert messages.

In some places, VMSes are set up with permanent, semi-static displays indicating predicted travel times to important traffic destinations such as major cities or interchanges along the route of a highway.

Typical messages provide the following information:

  • Promotional messages about services provided by a road authority during non-critical hours, such as carpooling efforts, travelers' information stations and 5-1-1 lines
  • Crashes, including vehicle spin-out or rollover
  • Road Works
  • Incidents affecting normal traffic flow in a lane or on shoulders
  • Non-recurring congestion, often a residual effect of cleared crash
  • Closures of an entire road, e.g. over a mountain pass in winter.
  • Exit ramp closures
  • Debris on roadway
  • Vehicle fires
  • Wildfires
  • Short-term maintenance or construction lasting less than three days
  • Pavement failure alerts
  • AMBER, Silver, and Blue Alerts, as well as weather warnings via the warning infrastructure of NOAA Weather Radio's SAME system
  • Travel times
  • Variable speed limits
  • Car park occupancy levels
  • speed sign, for recommending a speed to approach the next traffic light in its green phase.

The information comes from a variety of traffic monitoring and surveillance systems. It is expected that by providing real-time information on special events on the oncoming road, VMS can improve motorists' route selection, reduce travel time, mitigate the severity and duration of incidents and improve the performance of the transportation network.

United Kingdom

[edit]
  • Examples of variable message signs in the UK
  • Temporary advisory speed limit of 50 mph.
    Temporary advisory speed limit of 50 mph.
  • End of temporary restrictions.
    End of temporary restrictions.
  • Lane 2 is closed ahead.
    Lane 2 is closed ahead.
  • Lane 2 and 3 are closed ahead.
    Lane 2 and 3 are closed ahead.
  • Lane 1 is closed ahead.
    Lane 1 is closed ahead.
  • Lane 1 is closed ahead.
    Lane 1 is closed ahead.
  • Leave the motorway at the next junction.
    Leave the motorway at the next junction.
  • Both lanes are closed.*
    Both lanes are closed.*
  • All three lanes are closed.*
    All three lanes are closed.*
  • All 4 lanes are closed.*
    All 4 lanes are closed.*
  • Risk of ice ahead.
    Risk of ice ahead.
  • Risk of Fog ahead
    Risk of Fog ahead
  • Do not use the lane below the signal.
    Do not use the lane below the signal.

* Do not enter the motorway when the red lamps are flashing in pairs from side to side.

On 27 March 1972, the first motorway computer-controlled warning lights in the UK, with 59 miles on the M6 from Broughton, Lancashire to Barthomley, on the Cheshire boundary, and 26 miles on the M62 east of Whitefield, was switched on by Michael Heseltine and Charles Legh Shuldham Cornwall-Legh, 5th Baron Grey of Codnor at the headquarters of Cheshire Constabulary on Nuns Road.[7][8]

It was centred at a police computer centre at Westhoughton, that connected to police stations in Preston and Chester. The Chester site was soon be connected to the M53 and M57.[9] Four other regional computer centres would be opened at Perry Barr near the M6, Scratchwood near the M1, at Hook near the M3, and at Almondsbury near the M4. Most British motorways would be covered by 1975. The system was designed by GEC and had taken five years to design.[10]

Safety messages for drivers

[edit]

Increasingly, signs have been used to remind drivers to buckle seat belts ("Click it or ticket"), obey the speed limit, and stay off the road if impaired ("Drive sober or get pulled over").[11] In a federal study, a slight majority of drivers reported that public safety messages on dynamic message signs impacted their driving behaviors.[12]

The Ohio Department of Transportation began using humorous dynamic message signs in 2015, perplexing some drivers.[11] Examples[11][13][14][15][16][17][18] of humorous signs seen in New Jersey, Arizona, Texas, Pennsylvania, Delaware, Iowa, New York, Minnesota and Ohio include:

  • "Hold on to your butts. Help prevent forest fires."
  • "We'll be blunt. Don't drive high."
  • "Visiting in-laws? Slow down, get there late."
  • "Only sparklers should be lit." and “Don’t drive Star Spangled hammered."(for Fourth of July)
  • "Hocus pocus – drive with focus." and "Slow down in work zones - my mummy works here." (for Halloween)
  • "Drive Drunk and YULE be sorry." and “You’re not a Christmas tree. Don’t drive lit."
  • "HO HO HO, please drive slow." and "Don't be a grinch, let them merge."
  • "Reckless drivers are worse than fruitcake."
  • "Only Rudolph should be lit." and "Santa's watching, put down the phone."
  • “I’m just a sign asking drivers to use turn signals.”
  • “Seatbelts always pass a vibe check.”
  • “Come on, Eileen… your speed is obscene."
  • “May the 4th be with you, text I will not.”
  • "Irish you would slow down."
  • "I saw the sign and it opened up my eyes."
  • "Nice car, did it come with a turn signal?" and "Get your head out of your apps."
  • "100 is the temperature - not the speed limit."
  • “Let’s go Barbie, Buckle Up. Yes. You Ken!” and “Fast & Furious? Nope! Slow & Cautious.”

In 2024, concerns that these messages were distracting drivers led the Federal Highway Administration to strongly discourage signs with "obscure meanings, references to pop culture" or humor.[16]

Movable versions

[edit]
Trailer-mounted VMS in central London, England

Truck-mounted VMSes (also called Portable Changeable Message Signs or PCMS) are sometimes dispatched by highway agencies such as Caltrans to warn traffic of incidents such as accidents in areas where permanent VMSes are not available or near enough as a preventive measure for reducing secondary accidents. They are often deployed in pairs so that the second VMS truck can take over when the traffic queue overtakes the first truck, requiring the first truck to reposition further upstream from the queue, to be effective. An optional third truck, the team leader, may be utilized for driving by and monitoring the incident itself, traffic patterns and delay times, to make strategic decisions for minimizing delays—analogous to spotter planes used in fighting forest fires.

Trailer-mounted variable-message signs are used to alter traffic patterns near work zones, and for traffic management for special events, natural disasters, and other temporary traffic patterns. The messages displayed on the sign can be programmed locally on the unit's control panel, or units equipped with a cellular modem can be programmed remotely via computer or phone. Most manufacturers produce trailers which comply with the National Transportation Communications for Intelligent Transportation System Protocol (NTCIP) which allows the portable trailer to be integrated with an intelligent transportation system. Trailer-mounted VMS can be equipped with radar, cameras, and other sensing devices as part of a smart work zone deployment..

[edit]

A variable-message sign figures significantly into the plot of the 1991 film L.A. Story.

[edit]
  • A single row matrix LED sign on Katunayake Expressway in Colombo, Sri Lanka
    A single row matrix LED sign on Katunayake Expressway in Colombo, Sri Lanka
  • A three row fixed character matrix LED sign warns "Avoid London - Area Closed - Turn On Radio" following the 7 July 2005 London bombings
    A three row fixed character matrix LED sign warns "Avoid London - Area Closed - Turn On Radio" following the 7 July 2005 London bombings
  • Europe's largest Dynamic Route Guidance System, in Nuremberg, Germany (hybrid rotating prism and row matrix LED)
    Europe's largest Dynamic Route Guidance System, in Nuremberg, Germany (hybrid rotating prism and row matrix LED)
  • A dual row matrix LED sign on National Highway 4, in Bangalore, India
    A dual row matrix LED sign on National Highway 4, in Bangalore, India
  • A row matrix LED sign on an interchange of a German Autobahn with side graphics display.
    A row matrix LED sign on an interchange of a German Autobahn with side graphics display.
  • A full matrix sign on Highway 401 in Ontario, Canada.
    A full matrix sign on Highway 401 in Ontario, Canada.
  • A full matrix walk-in cabinet LED sign (manufactured by Skyline Products) displaying travel times on Interstate 70 north of Evergreen, Colorado, USA.
    A full matrix walk-in cabinet LED sign (manufactured by Skyline Products) displaying travel times on Interstate 70 north of Evergreen, Colorado, USA.
  • A dual row matrix LED sign in Manhattan reminding motorists to drive safely.
    A dual row matrix LED sign in Manhattan reminding motorists to drive safely.
  • A Daktronics rear access color LED sign on the New Jersey Turnpike, USA, displaying a warning about congestion ahead.
    A Daktronics rear access color LED sign on the New Jersey Turnpike, USA, displaying a warning about congestion ahead.
  • A set of LED signs on Interstate 90 in Mercer Island, Washington, USA, that warn of an upcoming lane closure due to a collision. Normally, these signs display variable speed limits that are adjusted during rush hour.
    A set of LED signs on Interstate 90 in Mercer Island, Washington, USA, that warn of an upcoming lane closure due to a collision. Normally, these signs display variable speed limits that are adjusted during rush hour.
  • A variable-message sign tells drivers that a section of the Hidaka Expressway in Hokkaido, Japan is damaged after the 2018 Hokkaido Eastern Iburi earthquake.
    A variable-message sign tells drivers that a section of the Hidaka Expressway in Hokkaido, Japan is damaged after the 2018 Hokkaido Eastern Iburi earthquake.
  • A sign in Winston-Salem, North Carolina, USA, displaying the website for information on COVID-19 in North Carolina.
    A sign in Winston-Salem, North Carolina, USA, displaying the website for information on COVID-19 in North Carolina.
  • Main South Road at the northern end of the Southern Expressway, Adelaide, Australia, during morning peak (looking south), closed to southbound traffic. This has now changed.
    Main South Road at the northern end of the Southern Expressway, Adelaide, Australia, during morning peak (looking south), closed to southbound traffic. This has now changed.
  • Variable message sign at the Changzhi Interchange in Taiwan
    Variable message sign at the Changzhi Interchange in Taiwan
  • Fully graphical variable message sign reminding motorists to reduce speed during rain in North-South Expressway, Perak, Malaysia
    Fully graphical variable message sign reminding motorists to reduce speed during rain in North-South Expressway, Perak, Malaysia
  • A "name-and-shame" variable message sign along the G18 Expressway in Shandong, China, which displays the licence plate numbers of offending motorists, along with the traffic infractions they've committed. In this example, the sign reads "鲁F982EX: Occupying the emergency lane, please drive according to the rules".
    A "name-and-shame" variable message sign along the G18 Expressway in Shandong, China, which displays the licence plate numbers of offending motorists, along with the traffic infractions they've committed. In this example, the sign reads "鲁F982EX: Occupying the emergency lane, please drive according to the rules".

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Variable-message sign

View on Grokipedia
from Grokipedia
A variable-message sign (VMS), also known as a changeable message sign or dynamic message sign, is an electronic traffic control device used on roadways to display real-time, programmable s informing drivers of incidents, congestion, roadwork, travel times, detours, speed limits, and special events. These signs are typically remotely operated from centers and adhere to standards for legibility, such as minimum 18-inch character height for visibility up to 800 feet at highway speeds. First deployed in the United States in the mid-1950s, with early examples at the by 1957 using scroll and rotating drum mechanisms, VMS have become integral to intelligent transportation systems for enhancing road safety and mobility. VMS employ technologies such as light-emitting diodes (LEDs) for or full-color displays—as increasingly adopted in recent years for better visibility and graphics—fiber optics, or flip-disc mechanisms to convey text, symbols, and graphics, with messages limited to concise formats like 3-4 units (groups of words) to ensure quick comprehension by motorists traveling at 35-70 mph. They come in permanent installations mounted above or beside highways and portable versions on trailers for temporary use in zones or incidents, both designed to withstand environmental factors like rain, fog, and glare while prioritizing verified, relevant information. Over the decades, advancements in LED efficiency and integration with sensors have expanded their role beyond basic warnings to include dynamic lane assignments, queue detection, and variable speed advisories, as outlined in federal guidelines like the Manual on Uniform Traffic Control Devices (MUTCD). Globally, VMS are deployed on major highways, urban arterials, and tunnels to manage and reduce delays, with operations emphasizing message prioritization—such as major accidents over minor roadwork—and coordination with services for timely updates. In the U.S., state departments of transportation like those in Washington and use VMS within broader active strategies to inform route choices and mitigate congestion, supported by research showing improved compliance and outcomes when messages are clear and credible.

Overview

Definition

A variable-message sign (VMS), also referred to as a changeable message sign (CMS) or dynamic message sign (DMS), is an electronic traffic control device capable of displaying one or more alternative messages to inform road users of real-time conditions such as traffic incidents, weather events, or roadway hazards. These signs function by electronically altering the displayed content to deliver timely, context-specific information that enhances driver awareness and decision-making on roadways. Key characteristics of VMS include the ability to remotely update messages via electronic control systems, allowing operators to modify content in response to changing conditions without physical intervention. They are typically mounted on overhead gantries, poles, or portable trailers along roadways to ensure broad visibility for approaching traffic. Designed for outdoor durability, VMS incorporate features such as automatic brightness adjustment to maintain legibility under diverse lighting and weather conditions, including direct sunlight or low-light scenarios. VMS differ from static signs, which feature fixed, unchanging text or symbols that cannot be altered remotely or in real time. Vehicle speed feedback signs, a specific type of CMS that provide interactive, vehicle-specific displays of detected speeds to encourage compliance, differ from general VMS, which focus on broadcasting non-interactive, variable informational content to all users.

Purpose and Benefits

Variable-message signs (VMS) serve as dynamic communication tools in transportation systems, delivering real-time information to drivers about traffic congestion, incidents, variable speed limits, roadwork schedules, and emergency alerts to guide behavioral adjustments such as route changes or speed reductions. By providing timely updates on these conditions, VMS enable motorists to make informed decisions, thereby mitigating risks associated with unexpected disruptions and promoting smoother traffic progression. The primary benefits of VMS include enhanced road safety through proactive warnings that reduce collision risks; for instance, variable speed limits displayed via VMS have been shown to achieve 20-30% reductions in overall crash rates, particularly for rear-end and lane-change incidents, by harmonizing traffic speeds during adverse conditions. These signs also improve by encouraging diversion to alternate routes, with studies indicating 5-20% shifts in traffic volumes during incidents, which helps alleviate bottlenecks and decrease average delays. In incident management, VMS support rapid response by alerting drivers upstream of hazards, leading to observed speed reductions of up to 3 mph in affected areas and fewer secondary accidents. As integral components of Intelligent Transportation Systems (ITS), VMS facilitate real-time data dissemination from sensors and traffic centers, enabling coordinated strategies for congestion control across networks. Their deployment yields substantial economic advantages, such as annual user cost savings exceeding $100 million in major urban reconstructions through delay reductions of up to 36%, demonstrating high benefit-to-cost ratios for congestion mitigation efforts.

History

Early Developments

The earliest precursors to modern variable-message signs (VMS) emerged in the mid-20th century, primarily as mechanical systems designed for basic traffic information display. , initial deployments occurred in the , with mechanical signs using rotating drums or panels to convey simple messages such as toll rates, parking availability, or entry warnings. For instance, by 1957, the approaches in New York and employed rotating drum mechanisms on the New Jersey side to display "DO NOT ENTER" alerts and scroll-based three-line messages on the New York side for traffic control. , similar mechanical approaches, including solenoid-actuated flip mechanisms for rudimentary variable displays, were experimented with during the , though widespread adoption lagged behind U.S. applications. These systems relied on manual or semi-automated operation, marking the transition from static to dynamic information provision amid growing postwar traffic volumes. The and saw the introduction of electronic matrix signs, shifting from purely mechanical designs to electrically controlled displays capable of forming alphanumeric characters. In the U.S., deployed its first VMS in the , using incandescent matrices to show conditions and incident warnings, setting a precedent for urban freeway management. Early experiments with fiber optic technology also began during this period, with initial tests in the exploring light-conducting bundles for brighter, more reliable matrix displays, though full deployments awaited refinements in the early . These innovations addressed limitations of mechanical signs, such as slower message changes and weather vulnerability, by enabling and real-time updates via basic . Pioneering efforts in electronic traffic control, including VMS, were advanced by traffic engineers at the (FHWA), which supported research into changeable message technologies through the 1970s. A seminal 1977 FHWA report reviewed operational experiences with early electronic systems, emphasizing their role in freeway . Key patents from this era, such as U.S. 3,509,652 (1970) for an illuminated vehicle adaptable to use and U.S. 4,040,194 (1977) for a magnetic flip-disc changeable message construction, credited inventors like those in firms for foundational designs that influenced FHWA guidelines. These contributions laid the groundwork for integrating VMS into national standards, prioritizing safety and efficiency in early intelligent transportation systems.

Modern Adoption and Expansion

The adoption of variable-message signs (VMS) accelerated in the 1990s and 2000s, driven by legislative mandates in key regions. In the United States, the (ISTEA) of 1991 established the foundation for the Intelligent Transportation Systems (ITS) program, which funded and promoted the deployment of VMS as part of broader efforts to enhance and efficiency. This led to significant growth, with VMS coverage on freeways expanding from 15% of miles in 1999 to 28% by 2004 across 78 large metropolitan areas, resulting in thousands of installations nationwide by the mid-2000s. In , directives such as the 2008/96/EC on road infrastructure safety management included variable message signs as part of intelligent transport systems equipment for road safety, spurring widespread installations; for instance, over 200 VMS were deployed on Paris's ring freeways alone by the early 2000s, contributing to thousands across the continent. From the onward, VMS proliferation surged in the region, particularly in , where deployments supported dynamic road traffic information systems amid rapid . This expansion aligned with initiatives that prioritize connected . In , the 's fastest-growing market, VMS deployments emphasized real-time road connectivity to handle increasing mobility demands. Policy drivers for VMS adoption have centered on addressing escalating urban congestion and major events, with systems enabling dynamic messaging to optimize . During the 2008 Beijing Olympics, VMS were extensively used for real-time traffic guidance, effectively managing event-related congestion and demonstrating their role in large-scale operations. Such implementations have become standard in response to global trends, where VMS help mitigate delays and enhance safety without requiring extensive physical infrastructure changes. As of 2025, ongoing integrations with advanced sensors and AI continue to expand VMS capabilities in intelligent transportation systems.

Technologies

Display and Hardware Types

Variable message signs (VMS) predominantly employ (LED) matrices as their core display technology, enabling full-color rendering and high brightness levels essential for visibility in diverse outdoor environments. These LED systems consist of pixel arrays that illuminate to form text, symbols, and graphics, with modern implementations favoring full-matrix configurations where the entire sign face comprises individually addressable pixels for maximum flexibility in message design. In contrast, legacy systems utilized fiber optic displays, which routed light through bundles of optical fibers from a central source to individual pixels, and displays (LCDs), which modulated light via liquid crystals sandwiched between polarizing filters, though these have largely been phased out due to limitations in brightness and durability under sunlight exposure. Key hardware components of VMS displays include the pixel pitch, typically ranging from 16 to 25 in LED matrices, which determines resolution and ; for instance, a 20 pitch supports clear viewing from up to 400 under optimal conditions, suitable for applications where drivers approach at speeds requiring rapid comprehension from 200-500 . Enclosures housing these displays are engineered for rugged outdoor deployment, featuring weatherproof ratings of IP65 or higher to safeguard against ingress, jets, and extreme temperatures, often incorporating aluminum or materials with ventilation systems to prevent . Power sources vary by installation type, with fixed roadside VMS drawing from grid and remote or portable units integrating solar panels paired with battery banks to ensure continuous operation in off-grid locations. LED-based VMS offer significant advantages over earlier incandescent or fiber optic variants, consuming up to 70% less power while delivering superior sunlight readability through automatic dimming and high exceeding nits. Full-matrix LED displays provide greater versatility than character-based variants, which limit output to predefined fonts and fixed positions per line, allowing only basic text messages; full-matrix systems, however, support dynamic graphics and multi-line layouts for enhanced information conveyance. This evolution from mechanical flip-disc and early electronic types to LED dominance has improved reliability and energy efficiency in modern deployments.

Control and Communication Systems

Control systems for variable-message signs (VMS), also known as dynamic message signs (DMS), are typically centralized within centers (TMCs) that employ supervisory control and (SCADA)-like software to oversee operations. These systems enable operators to messages based on predefined timelines, durations, and priorities, while allowing manual overrides for urgent situations, such as traffic incidents, to ensure timely dissemination of critical information. The software supports multi-user access with role-based permissions, facilitating coordinated management across networks of signs and arbitrating competing requests on a first-come-first-served basis. Communication protocols ensure between central control systems and field devices, with the National Transportation Communications for ITS Protocol (NTCIP) serving as the primary standard in the United States. NTCIP 1203 specifically defines data elements and object types using the (SNMP) to control and monitor VMS, including message formatting in MULTI syntax for complex text and graphics. Transmission options include hardwired fiber optic connections for reliable, high-bandwidth transfer from sensors, as well as wireless technologies like /LTE or emerging networks to support remote deployments and dynamic updates in areas without fixed infrastructure. Key features of these systems include automated algorithms for message prioritization, where incident-related alerts (e.g., accidents or closures) take precedence over general information like travel times, using predefined priority levels to optimize display sequences. Integration with sources such as cameras, GPS-enabled detectors, and environmental sensors allows for automated content generation, where real-time inputs trigger tailored messages to enhance and safety without constant manual intervention.

Standards and Specifications

International and Regional Standards

Variable-message signs (VMS) are governed by a range of international and regional standards that ensure interoperability, safety, and effective communication in intelligent transportation systems (ITS). The (ISO) standard ISO 14823 establishes a graphic for ITS, providing standardized codes for road traffic signs and pictograms used in messaging, including interfaces for VMS to support efficient encoding and display of traffic information. Complementing this, the (CEN) Technical Committee 226 (CEN/TC 226) develops guidelines on message content for VMS, focusing on road equipment standards that promote consistent and clear information delivery to road users. In the United States, the Federal Highway Administration (FHWA) Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition (effective January 18, 2024), specifies requirements for VMS, specifying yellow or amber backgrounds with black legend for standard displays, though full-color options are permitted for certain messages to enhance visibility and legibility under varying light conditions, along with minimum character sizes such as 18 inches for expressways to ensure readability at highway speeds. Additionally, the National Transportation Communications for ITS Protocol (NTCIP) 1201 standard defines global object definitions for ITS devices, including protocols for monitoring and controlling dynamic message signs (a subset of VMS), enabling seamless integration across transportation management systems. European regulations emphasize performance criteria through EN 12966, which outlines optical and electrical properties for VMS, covering aspects such as luminance, , and power supply requirements for both continuous and discontinuous sign types to withstand environmental stresses and ensure reliable operation. In , the Indian Roads Congress (IRC) Special Publication 85 (IRC:SP:85-2023, first revision) provides guidelines tailored for VMS deployment on highways and urban roads, incorporating adaptations for tropical climates like high and extremes to maintain display durability and message clarity.

Design and Legibility Requirements

Variable-message signs (VMS) must meet stringent standards to ensure drivers can read messages quickly and accurately under varying conditions. According to (FHWA) human factors guidelines, character heights should subtend a minimum of 20 arc minutes for dynamic elements, corresponding to legibility distances of approximately 750 feet for 18-inch characters on highways with speeds of 55 mph or greater. The Manual on Uniform Traffic Control Devices (MUTCD) specifies that VMS must be legible from at least 800 feet during daylight and 600 feet at night, with minimum letter heights of 18 inches for roads at or above 45 mph. contrast ratios are required to be between 8:1 and 12:1, with a preference for positive contrast (luminous characters on a dark background) to enhance ; minimum ratios as low as 3:1 may suffice in low ambient light but are not recommended for highway use. Brightness levels typically range from 500 to 1,000 cd/, adjustable automatically to ambient conditions, ensuring visibility in overcast daylight (up to 1,000 cd/ for older drivers) while dimming to around 30 cd/ at night to prevent glare. Message design prioritizes simplicity and rapid comprehension to minimize driver distraction. The FHWA recommends using the Standard Alphabets series (e.g., Series E Modified) for fonts, with a width-to-height of 0.7 to 1.0 and stroke width-to-height of 1:6 to 1:10, ensuring clear, uppercase lettering without serifs. Messages are limited to a maximum of three lines per phase, with line spacing at 50-75% of letter height, to fit within typical VMS panel dimensions while allowing drivers 1-2 seconds to process each unit of . Dwell times per phase should be at least 2 seconds or 1 second per word (whichever is greater), with full message cycles not exceeding 8 seconds for two-phase displays; transitions between phases must blank for no more than 0.3 seconds to avoid confusion. These parameters align with NTCIP protocols for consistent implementation across systems. Durability requirements ensure VMS withstand environmental stresses without compromising performance. Under European Standard EN 12966, VMS must resist wind loads up to 1.6 kN/m², equivalent to gusts of 180 km/h (112 mph), while U.S. specifications like those from AASHTO and state DOTs often require resistance to 145 km/h (90 mph) with a 30% gust factor. ranges are typically -40°C to +60°C, with enclosures rated for IP65 or higher to protect against moisture, dust, and thermal cycling. For sunlight readability, anti-glare coatings or protective screens are mandatory, reducing reflections by diffusing ambient light while maintaining high (over 90%) to preserve message clarity in direct sun.

Applications and Usage

Fixed Roadway Installations

Fixed variable-message signs (VMS), also known as dynamic message signs (DMS), are permanently integrated into roadway infrastructure to deliver real-time information on highways and major arterials. These installations typically feature overhead gantry-mounted units spanning multiple lanes for optimal visibility, or roadside pole-mounted configurations for targeted coverage in areas with fewer lanes or space constraints. According to (FHWA) guidelines, permanent VMS are positioned 20 to 25 feet above the roadway surface, with display panels capable of showing three lines of up to 20 characters each to accommodate essential messaging under varying light conditions. Operationally, fixed VMS provide continuous updates on critical roadway conditions, including variable speed limits to adapt to or , dynamic toll pricing on managed lanes, and alerts for congestion, incidents, or lane closures. On the US Interstate system, these signs support traveler guidance by displaying messages such as expected travel times or recommendations, managed centrally from centers to optimize flow during peak periods or disruptions. FHWA documentation emphasizes their role in addressing non-recurrent events like crashes and roadwork, as well as environmental hazards such as or snow, ensuring messages are limited to 3-5 units of information based on prevailing speeds for driver comprehension. Maintenance practices for fixed VMS focus on reliability through remote diagnostics, which allow central monitoring of sign controllers for faults and performance issues, alongside scheduled on-site cleaning to prevent dust or debris from reducing legibility. FHWA recommends routine field inspections and to achieve at least 90% uptime for devices, including VMS, thereby minimizing downtime and preserving operational effectiveness across deployments.

Portable and Temporary Deployments

Portable variable message signs (VMS), also known as portable changeable message signs (PCMS), are typically trailer-mounted or truck-based units designed for rapid deployment in non-permanent settings. These systems often rely on solar panels combined with battery backups to ensure operation in remote or off-grid locations, allowing setup in as little as a few hours for work zones or incident sites. For instance, models like the Ver-Mac PCMS-320 feature a trailer-mounted configuration with , providing a 64 x 105 inch suitable for urban and temporary applications. In construction zones, portable VMS are widely used to warn of lane closures, speed reductions, and detours, adhering to standards such as the U.S. Manual on Uniform Traffic Control Devices (MUTCD), which specifies their role in temporary traffic control for roadway, lane, or ramp closures. The (FHWA) guidelines emphasize their deployment to inform motorists of unusual conditions, with components including a message display, , power source, and mounting equipment on trailers or vehicles. For events like sports stadium gatherings, these signs manage traffic flow by directing drivers to parking areas, designating ride-share zones, and notifying of road closures, as implemented by systems from All Traffic Solutions to prevent backups and enhance guest experience. Globally, portable VMS support disaster efforts, such as during floods or hurricanes, by displaying real-time warnings and evacuation guidance to protect public safety. Manufacturers like PhotonPlay offer battery-backed units with up to six days of autonomy and weather-resistant designs (IP65 rating) for such emergencies, enabling quick information dissemination in affected areas. Their advantages include high flexibility for non-fixed sites, allowing repositioning as conditions change, and integration of GPS tracking for optimal placement and real-time monitoring, as seen in OPTRAFFIC systems that support group management of multiple devices. This mobility contrasts with fixed installations by enabling swift adaptation to temporary needs without permanent infrastructure.

Regional Variations

North America

In the United States, variable message signs (VMS), commonly referred to as changeable message signs (CMS), dominate regional deployment, with oversight provided by the (FHWA) through national policies and coordination with state departments of transportation (DOTs). The FHWA's Manual on Uniform Traffic Control Devices (MUTCD) sets standards for their use, emphasizing traffic operational and guidance information without advertising. California exemplifies this leadership, with Caltrans operating over 800 permanent CMS as of 2015 to deliver real-time alerts on incidents, congestion, and events, integrated into statewide traffic management systems. A 2015 national survey of state DOTs and toll agencies reported approximately 3,800 CMS in operation as of that year; the number has grown with infrastructure investments such as the Bipartisan Infrastructure Law, though no comprehensive national total is available as of 2025 due to decentralized state management. In , VMS implementations vary by province but emphasize bilingual capabilities in regions like to serve English- and French-speaking drivers. 's Ministry of Transportation has upgraded its VMS since 2009 to full-color electronic displays with pictogram support for clearer multilingual messaging on conditions and hazards. Mexico's VMS usage focuses on its extensive network, which expanded significantly after the 1994 (NAFTA) to facilitate cross-border commerce and improve safety. Deployments include (ITS) integrations on major routes, such as the six VMS installed in 2025 along the Palmillas-Apaseo Highway for real-time traffic and weather advisories. North American VMS uniquely support emergency public safety efforts, including the nationwide system, where FHWA policy permits CMS to display details to aid rapid response. In hurricane-prone areas, they provide critical evacuation guidance, such as contraflow directions and shelter locations, as outlined in federal evacuation planning resources. The MUTCD's 11th Edition, published in 2023 with compliance updates through 2025, enhances LED uniformity for CMS by mandating white digits, standardized backgrounds, and consistent sizing to improve legibility across deployments.

Europe and Asia-Pacific

In Europe, variable-message signs (VMS) are governed by the EN 12966 standard, which establishes uniform requirements for product performance, including visibility, durability, and power efficiency, ensuring compliance across the for all public road deployments. This harmonized framework facilitates interoperability and safety on the (TEN-T). In the , extensively deploys VMS on smart motorways to deliver dynamic speed limits, incident warnings, and congestion updates, enhancing traffic flow on major routes like the M25 and M6. Multilingual support is incorporated in border regions through the use of standardized pictograms, which convey information like hazards or lane closures without relying on text, promoting comprehension for cross-border drivers in areas such as the along France-Germany or Belgium-Netherlands frontiers. In the region, VMS deployment emphasizes scalability to address urban density, with leading through widespread installation in smart cities. , for instance, integrates VMS into its advanced systems to provide real-time advisories on congestion and diversions, drawing from empirical studies showing driver response rates exceeding 70% to variable messaging. These signs often link with broader networks, including traffic cameras, to monitor and manage violations or hazards in high- zones. In , a 2025 trial in is testing solar-powered VMS for autonomous operation on remote highways, enabling adaptive signage for weather, wildlife, or road conditions in areas with limited grid access. Key regional differences highlight Europe's emphasis on environmental integration, with VMS designs prioritizing low-power LED displays to minimize and in line with sustainability directives. In contrast, focuses on massive scale in megacities, where China's expansion to 19 such urban centers by 2025 drives VMS proliferation to manage populations over 10 million, supporting intelligent transportation in hubs like and .

Effectiveness and Research

Safety and Behavioral Impacts

Variable message signs (VMS) significantly influence behavior by encouraging speed adjustments in response to real-time warnings, such as alerts or congestion notifications. Studies on dynamic speed feedback signs, a type of VMS, demonstrate reductions in mean speeds of about 4 mph for passenger vehicles and 2-4 mph across all vehicle types in work zones and urban areas. Additionally, VMS with concise messaging minimize by facilitating rapid information processing, as overly complex displays can increase glance times and impair ; research recommends brief, easy-to-recognize formats to enhance road network efficiency without diverting attention from driving tasks. In terms of safety metrics, VMS play a key role in preventing secondary crashes by alerting drivers to incidents ahead, allowing them to slow down and avoid queues. analyses indicate that changeable message signs can achieve up to a 10% reduction in injury crashes through improved speed management and harmonization. In work zones, the 11th Edition of the Manual on Uniform Traffic Control Devices (effective January 18, 2024) underscores the importance of portable changeable message signs for enhancing worker and road user safety, recommending their use to provide advance warnings of lane closures, hazards, and delays in temporary traffic control areas. Despite these benefits, VMS effectiveness can be limited by message overload, where frequent or excessive displays lead drivers to ignore subsequent information. Field experiments and literature reviews identify as a critical issue, resulting from too many phases or irrelevant messages that cause overload and diminish perceived reliability, particularly at high approach speeds or short reading distances.

Operational and Economic Studies

Operational studies on variable-message signs (VMS) have demonstrated their role in enhancing traffic throughput, particularly in congested urban networks. Field trials across nine European cities, conducted as part of EU-sponsored projects, showed that VMS providing dynamic time information and route guidance induced driver diversions, resulting in improved network times and modest reductions in overall congestion. Similarly, analyses of VMS deployments in the indicate that real-time messaging can increase traffic diversion rates by 5-20% during incidents, thereby boosting throughput in affected corridors by optimizing route choices and reducing bottlenecks. Reliability metrics for VMS systems in US deployments, leveraging modern LED , typically achieve uptime rates exceeding 99%, ensuring consistent information delivery even in adverse weather conditions. Economic evaluations highlight substantial returns from VMS investments through reduced delays and operational efficiencies. Benefit-to-cost ratios for dynamic message signs on US freeways have ranged from 1.38:1 to 16.95:1, primarily driven by fewer crashes and shorter travel times, equating to savings of $1.38 to $16.95 per dollar invested. A World Bank assessment of intelligent transportation systems, including VMS-based traveler information, identifies these as high-ROI interventions in developing countries, with benefits accruing from immediate congestion relief and long-term network optimization. The global VMS market is projected to grow from USD 2.54 billion in 2025 to USD 4.5 billion by 2035, reflecting increasing adoption for amid rising . Despite these advantages, VMS implementations face challenges related to upfront and ongoing costs. Installation costs for fixed VMS units typically range from $50,000 to $200,000 per sign, encompassing hardware, mounting, and integration with centers, as seen in state DOT projects for dynamic warning systems. Maintenance in remote or harsh environments adds further expense, with issues like battery degradation in portable units and connectivity failures potentially reducing system availability if not addressed through regular servicing. These factors underscore the need for strategic deployment to maximize economic viability.

Future Developments

Emerging Technologies

Recent advancements in variable-message sign (VMS) technology are incorporating (AI) for dynamic content generation, particularly through (ML) algorithms that forecast and generate predictive messages in real time. These systems analyze data from sensors, cameras, and historical patterns to anticipate delays, accidents, or weather impacts, allowing VMS to display tailored warnings or rerouting advice before issues escalate, thereby improving and driver response times. For instance, AI-powered platforms can optimize signal timing and update VMS messages autonomously, helping to reduce congestion in urban settings based on . Complementing these software innovations, hardware developments include organic light-emitting diode () displays, which enable thinner and lighter signs with improved display quality for urban deployment. Sustainability efforts in VMS are advancing through solar-integrated units that eliminate reliance on grid power for remote or off-grid locations, significantly lowering operational costs and environmental impact by harnessing for continuous operation. These systems, often combined with battery storage, provide high reliability with backup for several days of operation in areas without electrical , reducing carbon emissions associated with traditional power sources and supporting goals in transportation networks. Additionally, integration allows for localized data processing at the VMS level, minimizing latency in message updates and bandwidth usage by handling real-time on-site rather than relying on central servers, which enhances responsiveness during peak traffic events. As of 2025, notable pilots have demonstrated -enabled VMS within vehicle-to-everything () frameworks, facilitating direct communication between signs, vehicles, and infrastructure for enhanced safety and efficiency. In , trials such as the NTU Smart Campus testbed have integrated for safety applications like , paving the way for broader adoption. These developments underscore VMS evolution toward interconnected, proactive systems amid global rollout.

Integration with Intelligent Transportation Systems

Variable-message signs (VMS) play a pivotal role in Intelligent Transportation Systems (ITS) by facilitating real-time data exchange with traffic sensors, such as and inductive loops, to detect incidents like crashes or congestion and automatically update signage for traffic diversion and alerts. This integration enables VMS to receive inputs from vehicle detection systems, processing sensor data to display dynamic messages that inform drivers of hazards, travel times, or route changes, thereby enhancing overall . Additionally, VMS connect with Advanced Driver Assistance Systems (ADAS) through Vehicle-to-Infrastructure (V2I) communication protocols, broadcasting safety warnings—such as wrong-way driving detections or work zone notifications—to equipped , which can then trigger automated responses like speed adjustments. Cloud platforms further unify these elements by aggregating sensor and ADAS data via AI-driven analytics, allowing VMS to issue coordinated alerts across networks for predictive incident and reduced response times. In future Cooperative ITS (C-ITS) scenarios, VMS are envisioned to synchronize seamlessly with vehicle apps and onboard systems, enabling bidirectional data flow for enhanced ; for instance, the C-ROADS project tests such across borders, where VMS relay status to vehicles while receiving real-time feedback from connected apps to optimize message relevance. This framework supports broader connected mobility, with projections indicating full compatibility with autonomous vehicles by 2030 through standardized digital interfaces that address current challenges like LED readability for in VMS. As of 2025, VMS integration with emerging standards continues to evolve, including considerations for cybersecurity and AI ethics in message generation. Addressing integration challenges, cybersecurity protocols like ISO/SAE 21434 are essential for securing V2I exchanges in VMS-ITS ecosystems, providing a lifecycle framework for risk assessment and threat mitigation to prevent unauthorized access or message tampering. These measures, extended from vehicle to infrastructure applications, ensure resilient data flows amid growing connectivity. Ultimately, such advancements position VMS as key contributors to zero-fatality road goals under initiatives, where real-time alerts from integrated ITS reduce speed-related incidents and severe crashes by informing behavioral adjustments.

References

  1. https://tsmowa.org/category/intelligent-transportation-systems/variable-message-signs
  2. https://www.nj.gov/transportation/business/research/reports/FHWA-NJ-2001-010.pdf
  3. https://transportationhistory.org/2022/04/11/national-work-zone-awareness-week-nwzaw-changeable-message-signs-for-highway-construction-areas/
  4. https://optraffic.com/blog/customled-variable-message-signs-regions/
  5. https://www.fhwa.dot.gov/publications/research/infrastructure/pavements/ltpp/reports/03066/
  6. https://mutcd.fhwa.dot.gov/pdfs/11th_Edition/part2l.pdf
  7. https://www.dot.ny.gov/divisions/operating/oom/transportation-systems/repository/VMS%20Guidelines%20December%202018%20-%20FINAL.pdf
  8. https://mutcd.fhwa.dot.gov/pdfs/11th_Edition/mutcd11theditionhl.pdf
  9. https://www.montgomerycountymd.gov/DOT-TMC/Information/getvms.html
  10. https://www.roads.maryland.gov/opr_research/md-13-sp109b4c_impact-of-dms-messages_report.pdf
  11. https://ops.fhwa.dot.gov/publications/fhwahop17003/ch4.htm
  12. https://ops.fhwa.dot.gov/publications/mitig_traf_cong/mitig_traf_cong.pdf
  13. https://www.roads.org.uk/articles/mixed-signals
  14. https://www.researchgate.net/publication/228269818_Effectiveness_of_Variable_Message_Signs
  15. https://web.sunrisesesatech.com/resources/dynamic-message-signs-differences-between-europe-and-north-america
  16. https://rosap.ntl.bts.gov/view/dot/75571/dot_75571_DS1.pdf
  17. https://patents.google.com/patent/US3509652A/en
  18. https://patents.justia.com/patent/4040194
  19. https://www.itskrs.its.dot.gov/sites/default/files/deployment-statistics/final/2004_Final_Report.pdf
  20. https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:02008L0096-20191216
  21. https://rosap.ntl.bts.gov/view/dot/14030/dot_14030_DS1.pdf
  22. https://haiyan-huang.com/signage-system
  23. https://www.linkedin.com/pulse/asia-pacific-variable-message-traffic-signs-market-size-ayu3c/
  24. https://www.photonplay.com/blog/everything-you-need-to-know-about-variable-message-signs
  25. https://www.sciencedirect.com/science/article/pii/S157066720960009X
  26. https://www.linkedin.com/pulse/united-states-variable-message-signs-intelligent-transportation-ilzrc
  27. https://ops.fhwa.dot.gov/publications/fhwahop18067/fhwahop18067.pdf
  28. https://www.photonplayinc.com/blog/variable-message-signs-an-ultimate-innovation-to-get-a-control-over-the-traffic
  29. https://optraffic.com/blog/technology-portable-variable-message-sign/
  30. https://www.diva-portal.org/smash/get/diva2:674015/FULLTEXT01.pdf
  31. https://www.daktronics.com/web-documents/transportation-documents/vanguard-products/dd3987003.pdf
  32. https://optraffic.com/blog/ip65-other-ip-ratings-difference-why-matters/
  33. https://kutuotraffic.com/products/solar-powered-vms-trailer/
  34. https://www.absen.com/current-status-and-future-trends-of-energy-saving-technologies-in-led-displays/
  35. https://www.energy.gov/energysaver/led-lighting
  36. https://ops.fhwa.dot.gov/publications/fhwahop18080/fhwahop18080.pdf
  37. https://www.ntcip.org/file/2018/11/NTCIP1203v03f.pdf
  38. https://www.ntcip.org/dynamic-message-signs/
  39. https://www.codot.gov/programs/dmo/fiber-optics-golden-threads
  40. https://www.fhwa.dot.gov/publications/research/operations/20064/20064.pdf
  41. https://highways.dot.gov/media/8226
  42. https://www.iso.org/standard/76963.html
  43. https://standards.iteh.ai/catalog/tc/cen/70120d40-23bf-449e-9b6b-903b7b17d477/cen-tc-226
  44. https://www.ntcip.org/file/2018/11/NTCIP1201v0315r.pdf
  45. https://standards.iteh.ai/catalog/standards/cen/e1ca2f41-d234-450e-b158-f0104ff1ad82/en-12966-2014a1-2018
  46. https://www.irc.nic.in/WriteReadData/LINKS/IRC_Catalogue_2023_v10b8a7467-1008-48b5-a65f-37c409fa0341.pdf
  47. https://www.fhwa.dot.gov/publications/research/safety/98057/ch03.cfm
  48. https://mutcd.fhwa.dot.gov/htm/2009/part2/part2l.htm
  49. https://its-norway.no/wp-content/uploads/2013/09/16-Ernst_Swarco.pdf
  50. https://www.dot.ny.gov/spec-repository-us/645.45080025.pdf
  51. https://www.access-board.gov/research/communication/variable-message-signing/current-vms-technologies/
  52. https://highways.dot.gov/media/67556
  53. https://ops.fhwa.dot.gov/publications/fhwahop08043/cp_prim3_03.htm
  54. https://ops.fhwa.dot.gov/publications/fhwahop17003/fhwahop17003.pdf
  55. https://ops.fhwa.dot.gov/publications/fhwahop20025/fhwahop20025.pdf
  56. https://www.ver-mac.com/en/products/portable-changeable-message-signs/PCMS-320/
  57. https://mutcd.fhwa.dot.gov/pdfs/11th_Edition/part6.pdf
  58. https://www.alltrafficsolutions.com/work-with-us/entertainment-and-sports-stadium-wayfinding/
  59. https://www.photonplayinc.com/traffic-signs/variable-message-signs
  60. https://optraffic.com/products/portable-traffic-message-signsvms/
  61. https://ops.fhwa.dot.gov/travelinfo/resources/dmspolcy02906.htm
  62. https://mutcd.fhwa.dot.gov/
  63. https://dot.ca.gov/programs/traffic-operations/tim/cms
  64. https://www.sciencedirect.com/science/article/pii/S2046043016301721
  65. https://nap.nationalacademies.org/read/23070/chapter/10
  66. https://news.ontario.ca/en/release/31535/ontarios-bilingual-electronic-highway-signs-going-colour
  67. https://www.itscanada.ca/files/5%2520Lovicsek_Presentation_Bilingual%2520Pictogram%2520Messages%2520on%2520Ontario%2520VMS_30apr2013.pdf
  68. https://www.itsinternational.com/news/mexico-highway-its-deployment-kapsch
  69. https://www.kapsch.net/en/press/releases/ktc-20250805-pr-en
  70. https://ops.fhwa.dot.gov/publications/fhwahop12015/fhwahop12015.pdf
  71. https://mutcd.fhwa.dot.gov/res-memorandum_amber.htm
  72. https://www.fhwa.dot.gov/reports/hurricanevacuation/chapter2.htm
  73. https://optraffic.com/blog/mutcd-11th-edition-speed-display-signs-2025/
  74. https://mutcd.fhwa.dot.gov/pdfs/11th_Edition/mutcd11thedition.pdf
  75. https://knowledge.bsigroup.com/products/road-vertical-signs-variable-message-traffic-signs-1
  76. https://www.gov.uk/government/publications/know-your-traffic-signs/motorway-signs-signals-and-road-markings
  77. https://www.researchgate.net/publication/285700890_Comprehension_of_pictograms_for_variable_message_signs
  78. https://www.nsw.gov.au/ministerial-releases/smart-tech-trials-to-drive-safer-behaviour-on-roads
  79. https://www.carexpert.com.au/car-news/australian-state-to-trial-solar-powered-smart-highways
  80. https://www.telegra-europe.com/dynamic-message-signs-variable-message-signs
  81. https://businessabc.net/urban-expansion-china-to-lead-the-world-ranking-with-19-megacities-by-2025
  82. https://rosap.ntl.bts.gov/view/dot/57513/dot_57513_DS1.pdf
  83. https://journals.sagepub.com/doi/10.1177/1687814019841843
  84. https://highways.dot.gov/sites/fhwa.dot.gov/files/Safe_System_Approach_for_Speed_Management.pdf
  85. https://www.diva-portal.org/smash/get/diva2:669230/FULLTEXT01.pdf
  86. https://www.sciencedirect.com/science/article/abs/pii/S1369847821002527
  87. https://www.tandfonline.com/doi/abs/10.1080/0144164042000196080
  88. https://rosap.ntl.bts.gov/view/dot/62965/dot_62965_DS1.pdf
  89. https://www.12gate.technology/research/vms-variable-message-signs
  90. http://www.itskrs.its.dot.gov/2013-b00840
  91. https://documents1.worldbank.org/curated/en/902531468313538337/pdf/356770ITS0deve1ntries0Note101PUBLC1.pdf
  92. https://www.wiseguyreports.com/reports/variable-message-traffic-signs-market
  93. https://mdl.mndot.gov/_flysystem/fedora/2023-01/200014.pdf
  94. http://www.itskrs.its.dot.gov/2016-sc00365
  95. https://optraffic.com/blog/mechanical-failures-variable-messaging-signs/
  96. https://www.econolite.com/application-areas/predictive-traffic-management-systems/
  97. https://optraffic.com/blog/solar-powered-variable-message-signs-remote/
  98. https://www.alotceriot.com/revolutionizing-traffic-management-empowering-mobile-vms-iot-technology/
  99. https://autocrypt.io/v2x-development-projects-around-the-world/
  100. https://www.datainsightsmarket.com/reports/traffic-variable-message-signs-vms-1654384
  101. https://www.transportation.gov/grants/ss4a/ITS-use-cases
  102. https://www.fhwa.dot.gov/publications/research/operations/21015/21015.pdf
  103. https://www.appliedintuition.com/blog/iso-sae-21434-shaping-automotive-cybersecurity
  104. https://highways.dot.gov/safety/zero-deaths
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