Vehicle activated sign (VAS) is a generic term for a type of road

traffic sign 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 introduce ...

which displays a message conditional upon the presence, or speed, of a

road vehicle A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), water ...

. The devices are deployed on roadsides like regular traffic signs in various countries. They are intended to help drivers by alerting them and drawing attention to danger or other undesirable situation.

Sign types

Speed enforcing

These signs activate if an approaching vehicle is detected to be exceeding a preset speed threshold. The speed limit and/or a warning message will illuminate on the sign to remind the driver/rider to slow down. At some locations in the UK these devices are used for

speed limit enforcement Speed limits are enforced on most public roadways by authorities, with the purpose to improve driver compliance with speed limits. Methods used include roadside speed traps set up and operated by the police and automated roadside 'speed camera' ...

. Another variation of VAS displays the speed of any passing vehicle. If the vehicle is moving faster than the speed limit the number will flash, or be displayed in an alternate colour. Other signs also flash alternately between a number indicating the speed and an

emoticon An emoticon (, , rarely , ), short for "emotion icon", also known simply as an emote, is a pictorial representation of a facial expression using Character (symbol), characters—usually punctuation marks, numbers, and letters—to express a ...

. A

Smiley face A smiley, sometimes referred to as a smiley face, is a basic ideogram that represents a smiling face. Since the 1950s it has become part of popular culture worldwide, used either as a standalone ideogram, or as a form of communication, such a ...

is displayed if the vehicle is moving below the speed limit, while a sad face is displayed when the limit is being exceeded. This kind of VAS is widely deployed in

the Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

and

Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...

Hazard warning

These signs are installed on the approaches to hazards such as bends and junctions. If triggered they may display a warning message and/or an image of the appropriate road sign (sharp bend, junction, Overheight Warning, etc.).

Sydney, Australia Sydney ( ) is the capital city of the States and territories of Australia, state of New South Wales, and the most populous city in both Australia and List of cities in Oceania by population, Oceania. Located on Australia's east coast, the metro ...

has implemented a unique low-clearance hazard warning using a curtain of water directly in the path of the vehicle. "When a truck gets too close, ..., a curtain of water starts flowing and a stop sign is projected onto it. The result is a warning that's so in-your-face that not only do the trucks stop, but so do all of the cars around it."

Sign Design

Vehicle activated signs used on the public highways are normally designed to mirror the standard road traffic signs and in the UK to the TSR&GD standards, these signs should also be designed to EN12966:2014 to ensure the signs are fit for use on the public highways.

Sign effectiveness

In a 2002 study{{cite techreport, last1= Winnett, first1= M.A., last2= Wheeler, first2= A.H., date= January 2002, title= Vehicle-activated signs – a large scale evaluation, url= https://trl.co.uk/uploads/trl/documents/TRL548.pdf, url-status= live, page= 2, institution=

Transport Research Laboratory TRL Limited, trading as TRL (formerly Transport Research Laboratory) is an independent private company offering a transport consultancy and research service to the public and private sector. Originally established in 1933 by the UK Government a ...

, ISSN= 0968-4107, isbn= 1-84608-547-0, archive-url= https://web.archive.org/web/20211113225445/https://trl.co.uk/uploads/trl/documents/TRL548.pdf, archive-date= 13 November 2021, access-date= 13 November 2021 conducted by

TRL TRL or trl may refer to: Arts * Temporary Residence Limited, a record label * ''Total Request Live'', a former MTV show * TRL Awards (''Total Request Live''), an Italian music award Libraries * Tampines Regional Library, a regional library in Ta ...

for the UK

Department for Transport The Department for Transport (DfT) is a department of His Majesty's Government responsible for the English transport network and a limited number of transport matters in Scotland, Wales and Northern Ireland that have not been devolved. The d ...

one of the conclusions was that vehicle activated signs appear to be very effective in reducing speeds; in particular, they are capable of reducing the number of drivers who exceed the speed limit and who contribute disproportionately to the accident risk, without the need for enforcement such as speed cameras.

References

External links

Design Manual for Roads and Bridges 6.3.5 – Traffic Calming On Trunk Roads

Traffic Advisory Leaflet 1/03
Road safety Traffic signs