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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.
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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]
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:
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:
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.
* Do not enter the motorway when the red lamps are flashing in pairs from side to side.
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"). [7] In a federal study, a slight majority of drivers reported that public safety messages on dynamic message signs impacted their driving behaviors. [8]
The Ohio Department of Transportation began using humorous dynamic message signs in 2015, perplexing some drivers. [7] Examples [7] [9] [10] [11] [12] [13] [14] of humorous signs seen in New Jersey, Arizona, Texas, Pennsylvania, Delaware, Iowa, New York, Minnesota and Ohio include:
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. [12]
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..
A variable-message sign figures significantly into the plot of the 1991 film L.A. Story .
Traffic comprises pedestrians, vehicles, ridden or herded animals, trains, and other conveyances that use public ways (roads/sidewalks) for travel and transportation.
Speed limits on road traffic, as used in most countries, set the legal maximum speed at which vehicles may travel on a given stretch of road. Speed limits are generally indicated on a traffic sign reflecting the maximum permitted speed, expressed as kilometres per hour (km/h) or miles per hour (mph) or both. Speed limits are commonly set by the legislative bodies of national or provincial governments and enforced by national or regional police and judicial authorities. Speed limits may also be variable, or in some places nonexistent, such as on most of the Autobahnen in Germany.
Traffic signs or road signs are signs erected at the side of or above roads to give instructions or provide information to road users. The earliest signs were simple wooden or stone milestones. Later, signs with directional arms were introduced, for example the fingerposts in the United Kingdom and their wooden counterparts in Saxony.
Motorway Incident Detection and Automatic Signalling, usually abbreviated to MIDAS, is a UK distributed network of traffic sensors, mainly inductive loops, which are designed to alert the local regional control centre (RCC) to traffic flow and average speeds, and set variable message signs and advisory speed limits with little human intervention. Companies such as RAC, TomTom and Google use this traffic flow data via halogens reporting systems.
The Schuylkill Expressway, locally known as "the Schuylkill", is a freeway through southern Montgomery County and Philadelphia. It is the easternmost segment of Interstate 76 (I-76) in the U.S. state of Pennsylvania. It extends from the Valley Forge interchange of the Pennsylvania Turnpike in King of Prussia, paralleling its namesake Schuylkill River for most of the route, southeast to the Walt Whitman Bridge over the Delaware River in South Philadelphia. It serves as the primary corridor into Philadelphia from points west. Maintenance and planning for most of the highway are administered through Pennsylvania Department of Transportation (PennDOT) District 6, with the Delaware River Port Authority (DRPA) maintaining the approach to the Walt Whitman Bridge.
Road signs in the United Kingdom and in its associated Crown dependencies and overseas territories conform broadly to European design norms, with a number of exceptions: direction signs omit European route numbers, and road signs generally use the imperial system of units, unlike the rest of Europe. Signs in Wales (Welsh) and parts of Scotland are bilingual.
North Klang Straits Bypass, Federal Route 20, AH 141, is the main highway bypass to Port Klang in Klang, Selangor, Malaysia. Federal Route 20 became the backbone of the road system linking Sungai Rasau to Port Klang before being surpassed by the New North Klang Straits Bypass 30. Many cargo trucks travel along the highway daily.
Road signs in Malaysia are standardised road signs similar to those used in Europe but with certain distinctions. Until the early 1980s, Malaysia closely practice in road sign design, with diamond-shaped warning signs and circular restrictive signs to regulate traffic. Signs usually use the Transport Heavy font on non-tolled roads and highways. Tolled expressways signs use a font specially designed for the Malaysian Highway Authority (LLM) which is LLM Lettering. It has two type of typefaces, LLM Narrow and LLM Normal. Older road signs used the FHWA Series fonts typeface also used in the United States, Canada, and Australia. Most road signs in Melaka and speed limit signs use Arial.
The Integrated Transport Information System (ITIS) is a traffic management system in Klang Valley, Malaysia. The system began operation on 2005 with the cooperation of Kuala Lumpur City Hall (DBKL), Malaysian Highway Authority, Malaysian Public Works Department (JKR) and the Ministry of Transport Malaysia. The system is used for traffic monitoring, accident, construction and other situations that happen on the roads and highways in Kuala Lumpur and Klang Valley. The main ITIS headquarters and traffic operation centre is located at Bukit Jalil Highway near Technology Park Malaysia in Bukit Jalil.
Road signs in Singapore closely follow those laid down in the traffic sign regulations used in the United Kingdom, although a number of changes over the years have introduced some slight deviations that suit local road conditions. Road signs in Singapore conform to the local Highway Code under the authority of Singapore Traffic Police.
Active traffic management is a method of increasing peak capacity and smoothing traffic flows on busy major highways. Techniques include variable speed limits, hard-shoulder running and ramp-metering controlled by overhead variable message signs. It has been implemented in several countries, including Germany, the United Kingdom, Canada and the United States.
A radar speed sign or speed feedback sign is an interactive sign comprising a speed-measuring device and a message sign generally constructed of a series of LEDs, which displays vehicle speed of approaching motorists. The purpose of radar speed signs is to slow cars down by making drivers aware when they are driving at speeds above the posted limits. They are used as a traffic calming device in addition to or instead of physical devices such as speed bumps and rumble strips.
An advisory speed limit is a speed recommendation by a governing body, used when it may be non-obvious to the driver that the safe speed is below the legal speed. It is a posting which either approximates the Basic Speed Law or rule or is based on a maximum g-force exerted at a specific speed. Advisory speed limits are often set in areas with many pedestrians, such as in city centres and outside schools, and on difficult stretches of roads, such as on tight corners or through roadworks. While travelling above the advisory speed limit is not illegal per se, it may be negligence per se and liability for any collisions that occur as a result of traveling above the limit can be placed partially or entirely on the person exceeding the advisory speed limit.
Road signs in Thailand are standardized road signs similar to those used in other nations but much of it resembles road signage systems used in South American countries with certain differences, such as using a blue circle instead of a red-bordered white circle to indicate mandatory actions. Until the early 1980s, Thailand closely followed American, European, Australian, and Japanese practices in road sign design, with diamond-shaped warning signs and circular restrictive signs to regulate traffic. The Department of Railway maintains a standard on the typeface used in the sign, with custom made type for Thai text, unofficially named "Thang Luang" (อักษรทางหลวง) and a small derivation of FHWA Series fonts typeface, which is used on American road signage, for Latin text. In most Bangkok Metropolitan Area's routes, TS Lopburi is still used.
The road signs of the Kingdom of the Netherlands — as well as Suriname are regulated in the Reglement verkeersregels en verkeerstekens 1990, commonly abbreviated as RVV 1990. While most previous signage, from the RVV 1966 remained legal and official, they have been updated/replaced. Some aren't official anymore and have lost legal validity, but most surviving old signs remained valid.
Road signs in South Korea are regulated by the Korean Road Traffic Authority.
In Japan, road signs are standardized by the "Order on Road Sign, Road Line, and Road Surface Marking (道路標識、区画線及び道路標示に関する命令)" established in 1968 with origins from the Tokyo Metropolitan Police Department's "Order on Standardization of Road Sign" of 1934 and the Home Ministry of Japan's "Order on Road Signs" of 1942. The previous designs have been used since 1986 after several amendments of order.
Road traffic control devices are markers, signs and signal devices used to inform, guide and control traffic, including pedestrians, motor vehicle drivers and bicyclists. These devices are usually placed adjacent, over or along the highways, roads, traffic facilities and other public areas that require traffic control.
Road signs in New Zealand are similar to those set by the Vienna Convention on Road Signs and Signals. While New Zealand is not a signatory to the convention, its road signs are generally close in shape and function. New Zealand uses yellow diamond-shaped signs for warnings in common with Australia, the Americas, Ireland, Japan and Thailand. Speed limit signs are a red circle with a white background and the limitation in black, and are in kilometres per hour. There are also some signs unique to New Zealand. Road signs in New Zealand are controlled by NZ Transport Agency Waka Kotahi and are prescribed in the Land Transport Rule: Traffic Control Devices 2004 and set out in the Traffic Control Devices (TCD) Manual.
Terminology related to road transport—the transport of passengers or goods on paved routes between places—is diverse, with variation between dialects of English. There may also be regional differences within a single country, and some terms differ based on the side of the road traffic drives on. This glossary is an alphabetical listing of road transport terms.
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