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In traffic engineering, there are regional and national variations in
traffic light Traffic lights, traffic signals, or stoplights – also known as robots in South Africa, Zambia, and Namibia – are signaling devices positioned at intersection (road), road intersections, pedestrian crossings, and other locations in order t ...
operation. This may be in the standard traffic light sequence (such as the inclusion of a red–amber phase) or by the use of special signals (such as flashing amber or public transport signals).


Flashing signals


Flashing red

In the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
and
Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
, a flashing red light is the equivalent of a
stop sign A stop sign is a traffic sign designed to notify drivers that they must come to a complete stop and make sure the intersection (road), intersection (or level crossing, railroad crossing) is safely clear of vehicles and pedestrians before contin ...
. In
New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
,
Hong Kong Hong Kong)., Legally Hong Kong, China in international treaties and organizations. is a special administrative region of China. With 7.5 million residents in a territory, Hong Kong is the fourth most densely populated region in the wor ...
, and the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
, paired red/red traffic lights are often installed outside fire and ambulance stations on major roads, which, when activated by the station, flash alternately (so that at any time one red light is showing), the purpose being to cause traffic to stop for a set amount of time to allow emergency vehicles to exit their station safely. The UK also uses an amber light which precedes the flashing red lights, and these signals are also used at level crossings, airfields and lifting bridges.


Flashing amber/yellow

In the US, Canada,
Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...
,
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
, and
The Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...
, flashing yellow does not require traffic to stop, but drivers should exercise caution since opposing traffic may enter the intersection after stopping. This may be used when there is a malfunction with the signals, or late at night when there is little traffic. A single four-way flashing light showing only one color in each direction may be used at intersections where full three-color operation is not needed, but stop or yield signs alone have not had acceptable safety performance. Yellow lights are displayed to the main road, to highlight the intersection and inform drivers of the need for caution. Red lights supplement stop signs on the side road approaches. All-way red flashing lights can supplement all-way stop control, but all-way yellow signals are prohibited by US regulations. In Canada a flashing yellow light at an intersection that would otherwise have traffic signals indicates that the traffic signals are malfunctioning. In this case the flashing yellow is seen by all vehicles approaching the intersection, and indicates that all vehicles must treat the intersection as a four way stop. All vehicles must come to a complete stop and yield right of way as per four way stop procedure. This would continue until the traffic signals have been fixed. In the UK and Ireland, flashing amber lights are used at
pelican crossing A pelican crossing is a type of pedestrian crossing with traffic signals for both pedestrians and vehicular traffic, activated by call buttons for pedestrians, with the walk signal being directly across the road from the pedestrian. Pelican cro ...
s to indicate that drivers should give way to pedestrians if they are still on the crossing, which replaces the normal red and amber phase used at other traffic signals. However in recent years in the UK, most pelican crossings are gradually being phased out in favour of puffin crossings or Pedex Crossings, as the flashing phase on pelican crossings has been deemed to be confusing to pedestrians and drivers alike. Also in the UK, twin flashing amber lights are used at cattle crossings and army tank crossings to warn drivers that they should give way at the crossing when the lights flash.


Flashing yellow arrow

In the US, a flashing yellow arrow is a signal phasing configuration for permissive left turns. An additional aspect displaying a yellow arrow is inserted between the yellow left turn arrow and the green left turn arrow. When the phase is active, the yellow arrow will flash. Drivers turning left or making a U-turn must be cautious and yield to both oncoming vehicles and pedestrians. The US MUTCD includes this meaning of the flashing yellow arrow, but though in 2008, the state had planned to require all new signals to have flashing yellow arrows, the 2011 Maryland MUTCD prohibits the flashing yellow arrow in favor of a flashing red arrow.
Tucson, Arizona Tucson (; ; ) is a city in Pima County, Arizona, United States, and its county seat. It is the second-most populous city in Arizona, behind Phoenix, Arizona, Phoenix, with a population of 542,630 in the 2020 United States census. The Tucson ...
uses a doghouse signal, with bimodal arrow (green and flashing yellow arrow) and a yellow arrow on the left and green and yellow balls on the right, topped by a red ball. During the permissive turn, the green ball and flashing yellow arrow are displayed. This can also prevent
yellow trap The yellow trap is a type of road traffic situation that may arise at certain signalized intersections, involving straight-moving traffic conflicting with turning, crossing traffic, that has made an erroneous assumption that the conflict has been ...
, which occurs when the circular signal turns yellow, and then red, while oncoming traffic still has a circular green. The MUTCD allows this signal with a special red light that can change into a ball, arrow, or a cross on intersections with lanes that are all reversible by lane control.
Sparks, Nevada Sparks is a city in Washoe County, Nevada, United States. It was founded in 1904, incorporated on March 15, 1905, and is located just east of Reno, Nevada, Reno. The 2020 U.S. Census counted 108,445 residents in the city. It is the List of citi ...
uses a similar arrangement: it uses a doghouse signal with green and yellow arrows (Steady or Flashing) on the left and green and yellow balls on the right, topped by a red ball, During the permissive turn, the flashing yellow arrow is displayed; but it could not prevent yellow trap because it is phased wrongly. The benefit of its introduction is that traffic engineers have a wider range of options to handle variable traffic volumes. According to the Minnesota Department for Transport, the flashing yellow arrow reduces delays and enhances safety. A research report from the National Cooperative Highway Research Program in the US found that it improves safety compared with a standard circular green signal. The flashing yellow arrow has an important safety advantage because it can be shown while the through signals on the same approach are red. The flashing yellow arrow is also meant to prevent yellow trap. Though '' Dallas phasing'' resolved the yellow trap issue, flashing yellow arrow has been deemed less confusing than a louvered green ball, and problems might arise if the left turn signal comes out of adjustment and its indications are visible to through traffic. In the United States, the flashing yellow arrow is not allowed where left turns and other traffic share the same lane. The circular green is still allowed as a permissive left-turn display, but has new restrictions: * It may not be placed over or in front of the left turn lane in new installations. * Any yellow trap caused by a circular green must be eliminated or warned with a sign. * If one lane is shared by left turning and straight ahead traffic, the left turn movement (protected or permissive) and the straight ahead movement must begin together and must end together at the same time in the signal cycle. In this case, a green left turn arrow may not be shown with a circular red, and a red left turn arrow may not be shown with a circular green or a straight ahead green arrow.


Flashing green

In Canada, there is disagreement between the provinces over the meaning of flashing green ball signals. Across most of Canada, such as Ontario, Quebec, New Brunswick, Nova Scotia, the Northwest Territories, and Nunavut (traffic lights in Nunavut are only temporary and not permanent), flashing green means an Advanced Green. This means traffic can turn left (across oncoming traffic) without needing to yield. The advanced green was originally chosen to be represented by flashing green because at the time of its introduction, in Ontario, a green arrow had meant that all traffic ''must turn'' in the direction of the arrow, although this is no longer the case. Additionally, an advanced green could be more easily added to existing three-lamp signals than could a green arrow, since it didn't require physically installing a fourth lamp for the arrow. British Columbia has adopted a non-standard meaning for a flashing green light, using it to indicate that the signal is controlled by pedestrians (and occasionally bikes). These signals are placed either at intersections or mid-block to allow pedestrians and cyclists to cross a major road. Traffic lights are only installed facing the major road approaches, and if there is a minor road it is controlled by stop signs. The signal will flash green until a pedestrian or cyclist is detected. The green light typically changes to a solid green indication for a few seconds before changing to yellow and then red but the solid green phase may be omitted depending on the road authority that installed the traffic light. The intention of the flashing green is to let drivers know that the signal will only change to yellow for pedestrians but otherwise "rests" in green. The US 2009 MUTCD specifically prohibits flashing any green signal indication. Protected flashing green is now used in parts of
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
and
Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...
as part of
traffic signal preemption Traffic signal preemption (also called traffic signal prioritisation) is a system that allows an operator to override the normal operation of traffic lights. The most common use of these systems manipulates traffic signals in the path of an emerg ...
for emergency vehicles. This does not conform to MUTCD. Flashing any green signal indication is also against the
Vienna Convention on Road Signs and Signals The Convention on Road Signs and Signals, commonly known as the Vienna Convention on Road Signs and Signals, is a multilateral treaty to standardize the signing system for road traffic (road signs, traffic lights and road markings) in use inte ...
. In Austria, Croatia and Estonia a flashing green light gives advance notice of a change to amber. However, this breaches the Vienna Convention.


Steady signals


Steady green arrows

Throughout most of the United States a protected turn (a turn that can be made without conflicting traffic) is indicated by a steady green arrow pointing in the direction of the turn. This indication may be displayed in a separate traffic signal head or may be in combination with other arrows or a green ball indication on the same signal such as with the Dallas Phasing configuration described below. Modern signal standards require that a yellow "clearance" interval be displayed for not less than three seconds prior to the protected turn interval ending. Throughout Canada, as in the United States, a green arrow indicates protected movement in the direction of the arrow. In
British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...
(permissive only),
Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...
,
Saskatchewan Saskatchewan is a Provinces and territories of Canada, province in Western Canada. It is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and to the south by the ...
,
Manitoba Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...
,
Kingston, Ontario Kingston is a city in Ontario, Canada, on the northeastern end of Lake Ontario. It is at the beginning of the St. Lawrence River and at the mouth of the Cataraqui River, the south end of the Rideau Canal. Kingston is near the Thousand Islands, ...
, and
Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...
, green turn arrows may or may not flash; both cases indicate a protected turn phase, but a flashing green arrow indicates that the protected phase will be followed by a permissive phase. In
Regina, Saskatchewan Regina ( ) is the capital city of the Provinces and territories of Canada, Canadian province of Saskatchewan. The city is the second-largest in the province, and is a commercial centre for southern Saskatchewan. As of the 2021 Canadian census, ...
, left-turn signals are designated by a two-bulb light configuration with one (or two) red balls and one LED bimodal arrow. When a left-turn cycle begins the red ball will change to a flashing green arrow to permitted all traffic turning left. When the left-turn cycle ends the flashing green arrow will turn to a solid amber arrow for five to three seconds then change back to a red ball. In the UK and many European countries, a green arrow may replace the full green light to indicate the direction in which movement is permitted for traffic in that lane. They may also have an additional green arrow below or on the left or the right of the other green arrow to permit drivers in that lane also to turn in that direction.


Hold-the-left and hold-the-right arrangements

In New Zealand, where traffic is on the left, when a road is given a green light from an all-direction stop, a red arrow can continue to display to turning traffic, holding traffic back while a pedestrian crossing on the side road is given a green signal (for left turns) or while oncoming traffic goes straight ahead and there is no permissive right turn allowed (for right turns). As soon as the pedestrian signal changes to flashing red, the red arrow for road traffic is extinguished. Traffic turning may then proceed provided they give way to oncoming traffic (for right turns) or pedestrians (for left turns). This method is becoming common in many states of Australia. When an intersection is given a protected turn prior to the pedestrian crossing on the side road being given a green signal, the lights change to yellow and red, and then the red arrow disappears as soon as the pedestrian crossing is given a flashing red signal.


Filter arrow

In the UK, a filter arrow is a green arrow which indicates to traffic that their movement does not conflict with any other movement and therefore they may proceed through the junction without stopping. It illuminates while the main signal is still at red. It is normally fixed to the left side of or underneath the green signal and shows a green left or ahead arrow. This means that a motorist may only proceed in the direction of the arrow. In the Province of
Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...
, a signal may display a green straight arrow alone, usually for five to nine seconds, and then the full green (or right turn arrow) illuminates. This allows pedestrians to emerge into the roadway, and therefore (in theory) increases safety. At a few intersections green arrows appear with the red ball to allow traffic to travel in a particular direction, but the red ball is always illuminated. Examples of where this occurs include the intersection of Delaware Avenue at Harrison Street in
Wilmington, Delaware Wilmington is the List of municipalities in Delaware, most populous city in the U.S. state of Delaware. The city was built on the site of Fort Christina, the first Swedish colonization of the Americas, Swedish settlement in North America. It lie ...
, and at the intersection of West 3rd Street and Mesaba Avenue in
Duluth, Minnesota Duluth ( ) is a Port, port city in the U.S. state of Minnesota and the county seat of St. Louis County, Minnesota, St. Louis County. Located on Lake Superior in Minnesota's Arrowhead Region, the city is a hub for cargo shipping. The population ...
. This is also true in Chicago; the straight off straight on ramps from Lake Shore Drive to N Fullerton Ave display a red light and left turn arrow or a red light, never just a green arrow. On the island of
Montreal Montreal is the List of towns in Quebec, largest city in the Provinces and territories of Canada, province of Quebec, the List of the largest municipalities in Canada by population, second-largest in Canada, and the List of North American cit ...
, Canada, it is forbidden to turn right while a red signal is present. At many intersections, lights will change from red to a green arrow permitting drivers to proceed straight through the intersection. This is called a leading through interval (LTI), after about five seconds or when the pedestrian signal changes to a flashing Orange Stophand, the green arrow is replaced with a green ball signal allowing drivers to proceed forward or turn as they wish.


Indicative arrow

In Hong Kong,
Ireland Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...
, Australia and the UK, a right arrow may sometimes be displayed alongside a green light to indicate that oncoming traffic has been stopped and that it is safe to turn right, however this does not necessarily mean that the turn is fully protected and road users should always check that there is no oncoming or approaching traffic before turning.


Japanese green arrows

In
Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
, a green arrow with the circular green is absolutely never shown. Instead, green arrows must be shown with the circular red. This means a signal may display green arrows pointing in all possible directions with the circular red. Another unusual sequence is that the circular red changes to circular yellow whenever some or all of the arrows end, and then changes back to red after the clearance period.


Steady red and amber arrows

In the UK, there are no red or yellow "arrow" lights, however there had been trials with the amber arrow in an attempt to prevent drivers from misinterpreting the signals. Also, turns are never permitted when a signal light is red. Layouts are typically simple: either the usual three-disc all-directions signal; the same with a separate green left or right ''filter'' arrow which lights up either independently of the main green (permitting a turn in the indicated direction at an otherwise red light) or along with it (showing that conflicting traffic has been stopped so turning traffic does not need to yield, also known as ''give way'' in the UK); or using adjacent sets where the horizontal positioning and lane layout (particularly where lanes are segregated by kerbs or islands) denotes which directions are stopped or free to move.


Dallas phasing

In the configuration commonly known as ''Dallas phasing'' that began in the Dallas/Fort Worth Metroplex, the five-light left turn signal head is used in a different manner than standard signals of this type. The left turn signal head operates independently from the signals for straight-through traffic. This allows permissive turning even when straight-through traffic is shown a red light, avoiding
yellow trap The yellow trap is a type of road traffic situation that may arise at certain signalized intersections, involving straight-moving traffic conflicting with turning, crossing traffic, that has made an erroneous assumption that the conflict has been ...
. Louvers are fitted over the green and yellow balls of the left turn signal head to prevent driver confusion. The left turn signal head is also accompanied by a sign indicating its special use. In this configuration, a green left arrow, with or without a circular green light, will only be displayed during a leading protected–left-turn phase. An amber left arrow is displayed to signal the end of the protected phase. This is followed by only a circular green light for the lagging permissive–left-turn phase, during which it is assumed that opposing traffic has both a permissive left turn and a straight-through green light. This can also be used in the opposite sequence, with the permissive left-turn phase leading and the protected left-turn phase lagging.Dallas Phasing With Doghouse ConfigurationLead Left-turn
/ref> Dallas phasing gives traffic engineers more flexibility with the leading and lagging protected left turn phase configurations allowing for better coordination between signals. There are also yellow and green arrows on Dallas phasing signals, permitting exclusive protected left-turn phases as well as protected/permissive left-turn phases. The 2009 Manual of Uniform Traffic Control Devices prohibits this display for new installations in favor of the flashing-yellow-arrow left-turn signal, which accommodates both permissive and protected left turns. Older installations are allowed to stay until they are replaced.


Arlington phasing

Arlington County, Virginia used the classic five-light "doghouse" (1971) with steady green and yellow arrows on the left, and green and yellow balls on the right, topped by a red ball. The light sequence started with a green arrow, proceeding to a yellow arrow, then a green ball, yellow ball, and finishing with a red ball. The signal was accompanied by a sign stating that left turns (against oncoming traffic) were required to yield on a green ball. These were later replaced by four-light signals that included a flashing yellow arrow.


Flashing red ball, yellow ball, or red arrow

Michigan Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...
uses a three-lamp traffic signal, with a red ball, yellow arrow, and green arrow; during the permissive turn, the red ball flashes. A flashing red ball signal on a "protected" left turn traffic signal indicates that left turning traffic may, after a full stop, complete their turn if and only if there is a long enough break in oncoming traffic. The flashing red usually occurs when the oncoming traffic has a green signal. This function is not enabled at intersections where it may not be safe to do so (restricted view of oncoming traffic, heavy pedestrian crossings, or double-lane left turns are good examples). Michigan usually indicates signals that are dedicated to turning traffic with a sign displaying "LEFT" or "RIGHT". This sign is normally illuminated at night. More recent installations in Michigan, however, have used flashing yellow arrow signal heads, which typically have not included left-turn signal signage. All flashing red ball signals in Michigan will gradually be phased out in favor of the flashing yellow arrow. The flashing red ball was also used in
Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east ...
.
Delaware Delaware ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic and South Atlantic states, South Atlantic regions of the United States. It borders Maryland to its south and west, Pennsylvania to its north, New Jersey ...
and
Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east ...
have also been known to place flashing red arrows at certain intersections, especially when no signal is needed for cross traffic. The driver is required to come to a complete stop before turning.
Cupertino, California Cupertino ( ) is a city in Santa Clara County, California, United States, directly west of San Jose, California, San Jose on the western edge of the Santa Clara Valley with portions extending into the foothills of the Santa Cruz Mountains. The ...
, also used a four-lamp signal, with a steady red arrow, a flashing red arrow, a steady yellow arrow, and a steady green arrow; during the permissive turn, the flashing red arrow was displayed. These flashing red arrows were later replaced with flashing yellow arrows.
Dover, Delaware Dover ( ) is the List of capitals in the United States, capital and the List of municipalities in Delaware, second-most populous city of the U.S. state of Delaware. It is also the county seat of Kent County, Delaware, Kent County and the princ ...
used a four-lamp signal. Forming a T, it has a flashing red arrow on the left, a steady red arrow on the right and yellow and green arrow on the bottom; during the permissive turn, the flashing red arrow is displayed.
Washington Washington most commonly refers to: * George Washington (1732–1799), the first president of the United States * Washington (state), a state in the Pacific Northwest of the United States * Washington, D.C., the capital of the United States ** A ...
state, particularly
Seattle Seattle ( ) is the most populous city in the U.S. state of Washington and in the Pacific Northwest region of North America. With a population of 780,995 in 2024, it is the 18th-most populous city in the United States. The city is the cou ...
, used a flashing yellow ball in the left-turn signal for the same purpose. Seattle also used a four-lamp signal at about 20 locations, with a red ball, a steady yellow ball, a flashing yellow ball, and a dual-mode yellow and green arrow; during the permissive turn, the flashing yellow ball was displayed. These were later replaced by flashing yellow arrows. The Delaware method of using flashing red arrows has been published in the 2009 MUTCD as an alternative to the flashing yellow arrow. However, this was allowed only when an engineering study determined that a "stop condition" must be imposed during the permissive left turn movement. While the Delaware method of flashing red arrows are allowed in the MUTCD as alternative to the flashing yellow arrow, the
Vienna Convention on Road Signs and Signals The Convention on Road Signs and Signals, commonly known as the Vienna Convention on Road Signs and Signals, is a multilateral treaty to standardize the signing system for road traffic (road signs, traffic lights and road markings) in use inte ...
explicitly prohibits flashing any red arrow indication. As stated in the Vienna Convention, flashing red lights "are only used at level crossing, swing bridge, airport, fire station or ferry terminal" and flashing red arrows are not allowed.


Australian turn arrows

In
Victoria Victoria most commonly refers to: * Queen Victoria (1819–1901), Queen of the United Kingdom and Empress of India * Victoria (state), a state of Australia * Victoria, British Columbia, Canada, a provincial capital * Victoria, Seychelles, the capi ...
, Australia, some intersections of this type employ a turn arrow without the red arrow. This would turn green with the main signal, before turning yellow, then off, giving priority to oncoming traffic. The nationwide standard seems to now include a red arrow that turns off. This arrow turns red simultaneously with the main light. After the cross traffic has had its turn, the arrows on opposite sides would both turn green, until one side runs out of right-turn traffic. In any case, when both sides of the intersection turn green, the corresponding arrow will turn off after a short delay, thus working similarly to the old Victorian standard. This method has the advantage of being controlled during peak hours, where controllers would be able to prevent the arrow from turning off in extreme peak-hour traffic, but causes confusion as drivers expect a light to be on when three are present.


Pedestrian crossings


Flashing pedestrian red

In Australia, New Zealand, some SADC countries (such as South Africa), Canada and most of the US, a flashing red or orange pedestrian signal is used at between green and steady red; it means "complete crossing but do not start to cross". This has a similar meaning to European flashing green, but means that if a pedestrian glances at it, they will not enter an intersection without enough time to leave. In the US and in parts of Canada, Australia and New Zealand (e.g., Auckland CBD) pedestrian signals which count down the number of seconds (see
Timers A timer or countdown timer is a type of clock that starts from a specified time duration and stops upon reaching 00:00. It can also usually be stopped manually before the whole duration has elapsed. An example of a simple timer is an hourglass ...
below) until cross traffic has the right of way are becoming popular at heavily used pedestrian crossings such as in urban shopping districts.


Flashing pedestrian green

In
British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...
, a flashing green globe signal is used at a
pedestrian crossing A pedestrian crossing (or crosswalk in American and Canadian English) is a place designated for pedestrians to cross a road, street or Avenue (landscape), avenue. The term "pedestrian crossing" is also used in the Vienna Convention on Road Sign ...
or intersection, at which pedestrians have the ability to stop traffic to allow a safe crossing. They may also be used at a drawbridge. The flashing green indicates that the signal is not currently in use. After the pedestrian pushes the button to trigger the signal, the light becomes a steady green until the sequence of yellow, then red (at which time the pedestrian crossing gives a signal) as in a conventional set of traffic lights, then returns to flashing green until another crossing is requested. This indication is also used in
Massachusetts Massachusetts ( ; ), officially the Commonwealth of Massachusetts, is a U.S. state, state in the New England region of the Northeastern United States. It borders the Atlantic Ocean and the Gulf of Maine to its east, Connecticut and Rhode ...
at fire stations and at crosswalks accompanied by a red and yellow pedestrian phase or a normal pedestrian signal. In several
Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
an countries and
Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
, a flashing green light is used in crosswalks to indicate that signal is going to change from green to red soon. Therefore, flashing green has roughly the same meaning to pedestrians as ordinary yellow signal has for motorists. Slow-moving pedestrians are warned about oncoming signal change and have opportunity to wait for next signal cycle. Motorists are more likely to notice flashing signal. Drivers of vehicles about to cross
pedestrian crossing A pedestrian crossing (or crosswalk in American and Canadian English) is a place designated for pedestrians to cross a road, street or Avenue (landscape), avenue. The term "pedestrian crossing" is also used in the Vienna Convention on Road Sign ...
s should be more aware of incoming pedestrians. Current users of flashing green signal are Austria, Belgium, Estonia, Finland, Great Britain, Hungary, Netherlands, Norway, Mexico, Poland, Russia, Spain and Sweden. France, Portugal and Switzerland make limited use of flashing green. In the UK and Ireland, the flashing pedestrian green signal is used at Pelican Crossings to indicate that pedestrians should not start to cross if they are not already on the crossing.


Pedestrian red–amber light

In
Massachusetts Massachusetts ( ; ), officially the Commonwealth of Massachusetts, is a U.S. state, state in the New England region of the Northeastern United States. It borders the Atlantic Ocean and the Gulf of Maine to its east, Connecticut and Rhode ...
, simultaneous red and yellow lights in all directions allow a pedestrian to cross diagonally. This replaces the conventional pedestrian signal, but is in violation of the MUTCD. This practice is obsolescent but it remains in the Massachusetts driver's manual.


Signage

In the UK, signs can be affixed to a signal head to emphasise a regulatory traffic sign. The most common use for these is prohibited turns.


Special signals


Transit priority signal

In
Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...
,
Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...
,
Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...
,
British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...
,
Nova Scotia Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...
,
Manitoba Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...
and
Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...
, traffic signals may also have an extra white rectangular light mounted above the red light. This phase indicates that a public transit vehiclebus, streetcar, or LRTmay proceed through an intersection in any direction while all other traffic faces a red light. In Ontario, this light is identical to the vertical "go" transit signal used in Western Europe. The horizontal "Stop" European transit signal is not used in Ontario. In some areas in Quebec, a white rectangular light is either mounted Above or below the main signal In some areas such as
Boston, Massachusetts Boston is the capital and most populous city in the Commonwealth (U.S. state), Commonwealth of Massachusetts in the United States. The city serves as the cultural and Financial centre, financial center of New England, a region of the Northeas ...
and
Denver, Colorado Denver ( ) is a List of municipalities in Colorado#Consolidated city and county, consolidated city and county, the List of capitals in the United States, capital and List of municipalities in Colorado, most populous city of the U.S. state of ...
a trolley may have its own traffic signals, indicating that it is okay for it to cross an intersection. These signals are all white, and the top section (stop) is a horizontal bar, the middle (caution) is an upright triangle, and the bottom (go) is a vertical bar. The horizontal bar is generally considered the "red" phase and symbolizes traffic flowing across the intersection from the perspective of the tram. In Australia and New Zealand, buses and trams may have a white "B" and "T" light respectively to indicate they may proceed through the intersection in any direction. A white arrow indicates that they only may proceed in the arrow's direction, common for trams to indicate that they may proceed and the
points A point is a small dot or the sharp tip of something. Point or points may refer to: Mathematics * Point (geometry), an entity that has a location in space or on a plane, but has no extent; more generally, an element of some abstract topologica ...
are set for proceeding that direction. Transit signals may be accompanied by red and yellow B/T signals indicating to buses and trams stop and caution respectively. Along the northern half of
Hong Kong Island Hong Kong Island () is an island in the southern part of Hong Kong. The island, known originally and on road signs simply as "Hong Kong", had a population of 1,289,500 and a population density of , . It is the second largest island in Hong Kon ...
, there is a similar "T" lamp in yellow for
double-decker tram A double-decker tram or double-deck tram is a tram that has two levels or decks. Some double-decker trams have open tops. Double-deck trams were once popular in some European cities, like Berlin and London, throughout the British Empire count ...
s.
Singapore Singapore, officially the Republic of Singapore, is an island country and city-state in Southeast Asia. The country's territory comprises one main island, 63 satellite islands and islets, and one outlying islet. It is about one degree ...
uses a similar "B" light for buses, but it is green. In many parts of Western Europe transit signals (for trams, and in some cases buses as well) employ traffic signals that are phased similarly to main traffic signals but replace the green light with a vertical white bar, the red light with a horizontal white bar and the yellow with a white dot or diamond. This is intended to avoid confusion between transit signals and main traffic signals at intersections where both sets are visible. In Russia, transit signals consist of four white lights, forming a "T". The bottom light is always illuminated when transit vehicles have permission to proceed. The top three lights represent the direction in which transit vehicles are permitted to proceed. For example, the left light allows transit vehicles to turn left, the middle light allows transit vehicles to proceed straight, and the right light allows transit vehicles to turn right. Multiple lights may be displayed at the same time, to allow transit vehicles to proceed in multiple directions at the same time. Transit signals are mostly used to give trams priority, but sometimes are used for buses and trolleybuses too. In the UK, although priority signals are not used, one such installation exists near Maidstone; a blue bus priority light which is located approximately 150 yards from the main traffic lights. When the sensor detects a bus, the blue light comes on for three seconds to let the bus driver know that it's detected the bus, and the traffic lights on that road immediately change to green to allow the bus through. No other installations are currently known to exist. In Orlando, Florida, a LYMMO Bus may have its own traffic signals in the downtown area. These signals are all white, and the top section (stop) is a horizontal bar, the middle (caution) uses a right slanted bar, the bottom (go) is the vertical bar.


Emergency priority signal

At many intersections in the US, intersections use
traffic signal preemption Traffic signal preemption (also called traffic signal prioritisation) is a system that allows an operator to override the normal operation of traffic lights. The most common use of these systems manipulates traffic signals in the path of an emerg ...
to give priority to emergency vehicles. These preemption applications often include an illuminated "notifier" signal. A notifier is a secondary lighting device usually mounted independently of the traffic signal, such as a standard or strobing light bulb in an omni-directional enclosure or spotlights aimed at oncoming traffic lanes. The colors of these secondary lighting devices vary regionally depending upon the operational policies of the local traffic management and emergency service agencies.


Reverse-side red indicator

Some jurisdictions use special small blue lights on the back sides of signal heads to indicate red -light state. They are used by police. Other jurisdictions simply drill a small hole in the red signal visor to allow police to see the status of the signal from a wide angle (but not directly opposite the signal). In France and, perhaps, Vietnam (which was previously a French colony by the name of Indochina), the back of the red lights are sometimes designed with a red cross to indicate that the light is red, so that opposing left-turning drivers know that oncoming traffic has been stopped.


Pre-warning of a changing signal


Between green and amber

In
Austria Austria, formally the Republic of Austria, is a landlocked country in Central Europe, lying in the Eastern Alps. It is a federation of nine Federal states of Austria, states, of which the capital Vienna is the List of largest cities in Aust ...
,
Cambodia Cambodia, officially the Kingdom of Cambodia, is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. It is bordered by Thailand to the northwest, Laos to the north, and Vietnam to the east, and has a coastline ...
,
China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...
,
Croatia Croatia, officially the Republic of Croatia, is a country in Central Europe, Central and Southeast Europe, on the coast of the Adriatic Sea. It borders Slovenia to the northwest, Hungary to the northeast, Serbia to the east, Bosnia and Herze ...
,
Estonia Estonia, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Ru ...
,
Latvia Latvia, officially the Republic of Latvia, is a country in the Baltic region of Northern Europe. It is one of the three Baltic states, along with Estonia to the north and Lithuania to the south. It borders Russia to the east and Belarus to t ...
,
Lithuania Lithuania, officially the Republic of Lithuania, is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea, bordered by Latvia to the north, Belarus to the east and south, P ...
,
Montenegro , image_flag = Flag of Montenegro.svg , image_coat = Coat of arms of Montenegro.svg , coa_size = 80 , national_motto = , national_anthem = () , image_map = Europe-Mont ...
,
Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
, most of
Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...
,
Malaysia Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...
, most of
Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
, some places in
Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...
,
Dominican Republic The Dominican Republic is a country located on the island of Hispaniola in the Greater Antilles of the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean. It shares a Maritime boundary, maritime border with Puerto Rico to the east and ...
,
Turkey Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...
,
Saudi Arabia Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in West Asia. Located in the centre of the Middle East, it covers the bulk of the Arabian Peninsula and has a land area of about , making it the List of Asian countries ...
, parts of
Serbia , image_flag = Flag of Serbia.svg , national_motto = , image_coat = Coat of arms of Serbia.svg , national_anthem = () , image_map = , map_caption = Location of Serbia (gree ...
, and in certain other parts of
Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
, the green lights will start flashing at the end of the Go or Turn phase to indicate that the yellow (Caution phase) lights are about to be engaged. This is useful in fast-paced roads to allow for longer slowing down time, and for pedestrians crossing broad streets. Some traffic lights in
Pennsylvania Pennsylvania, officially the Commonwealth of Pennsylvania, is a U.S. state, state spanning the Mid-Atlantic (United States), Mid-Atlantic, Northeastern United States, Northeastern, Appalachian, and Great Lakes region, Great Lakes regions o ...
illuminate the yellow light a few seconds before the green light turns off, to give this same warning, as did some lights in the Los Angeles area until at least the late 1970s, and one light in Glendale, AZ at 56th Avenue &Glenn until it was replaced in the early 1980s. Traffic lights in East Germany also used to turn on the amber light together with the green light to signify that the green phase is about to end. In the United States, the 2009 Manual of Uniform Traffic Control Devices prohibits any display that gives warning of an upcoming signal change, unless that display is placed well upstream of the signal (See "Warnings of traffic light ahead" below), so traffic at the stop line can not see it.


Between red and green

In most European countries (including Austria,
Belarus Belarus, officially the Republic of Belarus, is a landlocked country in Eastern Europe. It is bordered by Russia to the east and northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Belarus spans an a ...
,
Bosnia and Herzegovina Bosnia and Herzegovina, sometimes known as Bosnia-Herzegovina and informally as Bosnia, is a country in Southeast Europe. Situated on the Balkans, Balkan Peninsula, it borders Serbia to the east, Montenegro to the southeast, and Croatia to th ...
,
Bulgaria Bulgaria, officially the Republic of Bulgaria, is a country in Southeast Europe. It is situated on the eastern portion of the Balkans directly south of the Danube river and west of the Black Sea. Bulgaria is bordered by Greece and Turkey t ...
,
Croatia Croatia, officially the Republic of Croatia, is a country in Central Europe, Central and Southeast Europe, on the coast of the Adriatic Sea. It borders Slovenia to the northwest, Hungary to the northeast, Serbia to the east, Bosnia and Herze ...
, the
Czech Republic The Czech Republic, also known as Czechia, and historically known as Bohemia, is a landlocked country in Central Europe. The country is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the south ...
,
Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...
,
Estonia Estonia, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Ru ...
,
Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...
,
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
,
Hungary Hungary is a landlocked country in Central Europe. Spanning much of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and ...
,
Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...
, Latvia, Lithuania,
Malta Malta, officially the Republic of Malta, is an island country in Southern Europe located in the Mediterranean Sea, between Sicily and North Africa. It consists of an archipelago south of Italy, east of Tunisia, and north of Libya. The two ...
,
Moldova Moldova, officially the Republic of Moldova, is a Landlocked country, landlocked country in Eastern Europe, with an area of and population of 2.42 million. Moldova is bordered by Romania to the west and Ukraine to the north, east, and south. ...
, Montenegro,
North Macedonia North Macedonia, officially the Republic of North Macedonia, is a landlocked country in Southeast Europe. It shares land borders with Greece to the south, Albania to the west, Bulgaria to the east, Kosovo to the northwest and Serbia to the n ...
,
Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...
,
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...
, most of Russia, Serbia,
Slovakia Slovakia, officially the Slovak Republic, is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the west, and the Czech Republic to the northwest. Slovakia's m ...
,
Slovenia Slovenia, officially the Republic of Slovenia, is a country in Central Europe. It borders Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the south and southeast, and a short (46.6 km) coastline within the Adriati ...
,
Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...
,
Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...
,
Ukraine Ukraine is a country in Eastern Europe. It is the List of European countries by area, second-largest country in Europe after Russia, which Russia–Ukraine border, borders it to the east and northeast. Ukraine also borders Belarus to the nor ...
, and the UK), as well as in
Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...
,
Bahrain Bahrain, officially the Kingdom of Bahrain, is an island country in West Asia. Situated on the Persian Gulf, it comprises a small archipelago of 50 natural islands and an additional 33 artificial islands, centered on Bahrain Island, which mak ...
,
Botswana Botswana, officially the Republic of Botswana, is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory part of the Kalahari Desert. It is bordered by South Africa to the sou ...
,
Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...
,
Hong Kong Hong Kong)., Legally Hong Kong, China in international treaties and organizations. is a special administrative region of China. With 7.5 million residents in a territory, Hong Kong is the fourth most densely populated region in the wor ...
,
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
, some places in
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...
, Israel,
Liberia Liberia, officially the Republic of Liberia, is a country on the West African coast. It is bordered by Sierra Leone to Liberia–Sierra Leone border, its northwest, Guinea to Guinea–Liberia border, its north, Ivory Coast to Ivory Coast–Lib ...
,
Macau Macau or Macao is a special administrative regions of China, special administrative region of the People's Republic of China (PRC). With a population of about people and a land area of , it is the most List of countries and dependencies by p ...
,
Pakistan Pakistan, officially the Islamic Republic of Pakistan, is a country in South Asia. It is the List of countries and dependencies by population, fifth-most populous country, with a population of over 241.5 million, having the Islam by country# ...
,
Paraguay Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli ...
, and
the United Arab Emirates The United Arab Emirates (UAE), or simply the Emirates, is a country in West Asia, in the Middle East, at the eastern end of the Arabian Peninsula. It is a Federal monarchy, federal elective monarchy made up of Emirates of the United Arab E ...
, red and yellow lights are displayed together for one, two, or three seconds at the end of the red cycle to indicate that the light is about to change to green. This phase aids the drivers of vehicles to turn on the engines again (there are requests/advice to turn off engine in front of red traffic lights in some countries, e.g. Switzerland), or drivers with manual gearboxes, giving them time to change into first gear during the short phase, as well as drivers of vehicles that may have been yellow-trapped whilst turning right (or left in LHT countries) a chance to clear the intersection in more safety. It also informs drivers who may be approaching the intersection at speed that a green light is imminent, so they may proceed through the junction without having to stop (or, with enough of a lead distance, even having to slow), reducing the potential annoyance (and safety risk) of braking sharply to a halt only to have the green light appear immediately after.


Between green and red

Traffic lights in
Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...
, Italy and Sweden used to show a green and yellow light together, to indicate that the light was about to change to red. All countries now officially use a single yellow light instead, as displaying both the yellow and the green lights is in violation of the
Vienna Convention on Road Signs and Signals The Convention on Road Signs and Signals, commonly known as the Vienna Convention on Road Signs and Signals, is a multilateral treaty to standardize the signing system for road traffic (road signs, traffic lights and road markings) in use inte ...
.


Traffic signal ahead


Prepare to stop

In some areas, a "prepare to stop" sign with two alternately flashing yellow lights is installed in locations where a high-speed road (design speed usually at least 55 mph / 90 km/h) leads up to a traffic light, where the traffic light is obscured from a distance (or both conditions), or before the first traffic signal after a long stretch of road with no signals. This is installed so that drivers can view it from a distance. This light begins blinking with enough time for the driver to see it and slow down before the intersection light turns yellow, then red. The flashing yellow light can go out immediately when the light turns green, or it may continue for several seconds after the intersection light has turned green, as it usually takes a line of cars some time to accelerate to cruising speed from a red light. These are relatively common in areas such as the United States, Canada,
Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...
,
New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...
, New Zealand and Liberia. Japan uses a variant signal with two lamps, a green one and a flashing yellow one, for the same purpose. A common way of warning that an obscured traffic light ahead is red is a red-signal-ahead sign. It is shaped like a standard yellow diamond shape sign with LEDs spelling out "Signal Ahead". Just before the traffic light goes yellow, the word "Red" will light up above Signal Ahead and they will begin to flash alternately.


White strobe lights

A number of countries installed strobe lights on traffic signals until the 1990s. Such installations have since then been prohibited by both the FHWA and the Vienna Convention.


United States

In some parts of the US, a few traffic lights have slowly flashing white
strobe light A strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light. It is one of a number of devices that can be used as a stroboscope. The word originated from the Ancient Greek ('), meaning ...
s superimposed on the center of the red light, which are activated when the red light itself is illuminated. These are common on highways with few traffic signals; in high-traffic, and high-speed areas (where drivers running red lights are a major problem); in places where regular travelers would not expect a signal (such as a newly erected signal or one put up for construction); and in other situations where extra work may be needed to draw attention to the status of the light (such as in an area where many other red lights approximate the brightness, placement and color of a red traffic signal). The strobe may also be a flash from a camera located within the traffic signal itself (there has been much dispute as to whether this is legal or not). These are also used in areas prone to
fog Fog is a visible aerosol consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth's surface. Reprint from Fog can be considered a type of low-lying cloud usually resembling stratus and is heavily influenc ...
, as the strobing white light may be visible from a distance while the standard red light is not. A newer variant uses a flashing white LED ring located on the outer edge of the red indication as opposed to in the center of the red. Typically one strobe-equipped signal is mounted as a supplement between two normal signal heads. However such strobe installations have been prohibited by the
FHWA The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program a ...
since 1990; but individual states have been slow to conform. The current MUTCD (2009 edition) contains an explicit prohibition against their use; therefore, it is still FHWA's position that strobe lights are not allowed in traffic signals and no further experimentation with these types of strobe lights in traffic signals will be approved.This position was formalized on July 2, 2003 with an Official Interpretation of the MUTCD
number 4-263(I), "Strobes Florida DOT"
An example of this was located at the end of the Massachusetts I-90 Exit 51 in Chicopee, where the ramp ends at I-291. It has since been replaced with a completely modern design. Another example of this is at the intersection of Alabama State Route 53 and Dale County route 18 in which traffic approaching on AL-53 have a strobe light, although it appears that they no longer flash anymore and serve as a single red light now.


Europe and Asia

As in the US, strobe lights are not allowed in traffic signals in European and Asian countries. The
Vienna Convention on Road Signs and Signals The Convention on Road Signs and Signals, commonly known as the Vienna Convention on Road Signs and Signals, is a multilateral treaty to standardize the signing system for road traffic (road signs, traffic lights and road markings) in use inte ...
, including the European Annex, contains an explicit prohibition against their use, and any installation of strobe lights in traffic signals is in breach of the convention.


Unusual designs


Square backplates

Huntsville, Alabama Huntsville is the List of municipalities in Alabama, most populous city in the U.S. state of Alabama. The population of the city is estimated to be 241,114 in 2024, making it the List of United States cities by population, 100th-most populous ...
has a unique design for its traffic lights that use a square shaped backplate on the majority of its traffic lights. These square backplates have also been introduced to many Dallas doghouse traffic lights across the United States. Some newer traffic lights may have a reflective yellow outline on them, such as the ones at the intersection of Wynn Drive and Bradford Drive.


Shaped lenses

The Canadian provinces of
Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...
,
New Brunswick New Brunswick is a Provinces and Territories of Canada, province of Canada, bordering Quebec to the north, Nova Scotia to the east, the Gulf of Saint Lawrence to the northeast, the Bay of Fundy to the southeast, and the U.S. state of Maine to ...
, and
Prince Edward Island Prince Edward Island is an island Provinces and territories of Canada, province of Canada. While it is the smallest province by land area and population, it is the most densely populated. The island has several nicknames: "Garden of the Gulf", ...
generally use horizontal traffic lights with red to the left and green to the right. Such traffic lights are also found in
Nova Scotia Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...
and eastern
Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...
. These signals also use specific shapes for each color, which aids color-blind people in distinguishing signal aspects: * green – an ordinary "ball" shape, * yellow – a diamond shape, and * red – a square (somewhat larger than the ball shape).


Double red

In
Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...
, most horizontal traffic lights have a red signal on both sides of the fixture (left and right). They are also now replacing the shaped traffic lights for color-blind people with regular round signals. These are also seen on horizontal traffic lights in Eastern
Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...
and in
Nova Scotia Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...
. In some
Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...
urban areas, including
Houston Houston ( ) is the List of cities in Texas by population, most populous city in the U.S. state of Texas and in the Southern United States. Located in Southeast Texas near Galveston Bay and the Gulf of Mexico, it is the county seat, seat of ...
and
Dallas Dallas () is a city in the U.S. state of Texas and the most populous city in the Dallas–Fort Worth metroplex, the List of Texas metropolitan areas, most populous metropolitan area in Texas and the Metropolitan statistical area, fourth-most ...
, the use of a double red light is different. It is typically used on left turn signals. For horizontally mounted signals, typically hung or mounted over the lanes, it is configured with two red balls or arrows, one yellow arrow or ball, and a green arrow (from left to right). For vertically mounted signals, the two red balls or arrows are on the top, then a yellow arrow or ball, and a green arrow. It is usually accompanied by signs saying "left turn signal" or "left on arrow only". Signals for traffic going straight use standard signals, usually mounted horizontally over the road. The use of two red lights on the left turn signal allows for redundancy in case one of the red lights burns out, while saving money by requiring only one signal for left turns per direction that needs one. It also prevents the
yellow trap The yellow trap is a type of road traffic situation that may arise at certain signalized intersections, involving straight-moving traffic conflicting with turning, crossing traffic, that has made an erroneous assumption that the conflict has been ...
that would occur at night if a single red signal burned out and left-turning vehicles obeyed the circular signals instead. One type of installation in Texas uses a double red light instead of a single red light to make the red light more pronounced and visible from a distance. In this installation, it is the first traffic light on a rural highway for miles, and traffic approaches at highway speed (65 mph). The double red light makes the red phase of the light visible at a greater distance than the yellow and green on the same signal. This installation is also used on rural highways in
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
, always in a vertical configuration, and in either configuration in some cities of
Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
, such as
Guadalajara Guadalajara ( ; ) is the capital and the most populous city in the western Mexican List of states of Mexico, state of Jalisco, as well as the most densely populated municipality in Jalisco. According to the 2020 census, the city has a population ...
. The double-red light also appears in Georgia, South Carolina and North Carolina in left-hand turn lanes. It serves the same purpose as the vertical Texan configuration, and mainly appears on boulevards with multiple lanes of traffic where a left turn is dangerous due to poor visibility. Double red arrows are used for left turn installations on some county-managed roads in
Henrico County, Virginia Henrico County , officially the County of Henrico, is a County (United States), county located in the Commonwealth (U.S. state), Commonwealth of Virginia in the United States. As of the 2020 United States census, 2020 census, the population wa ...
and
Baltimore County, Maryland Baltimore County ( , locally: or ) is the third-most populous county in the U.S. state of Maryland. The county is part of the Central Maryland region of the state. Baltimore County partly surrounds but does not include the independent cit ...
. The double–red-ball aspect is used in
Saskatchewan Saskatchewan is a Provinces and territories of Canada, province in Western Canada. It is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and to the south by the ...
and
Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...
, Canada, to indicate a protected-prohibited left turn signal. A sign with the universal ''no left turn'' symbol and a depiction of the double red light is mounted near the signal to indicate that no left turns are permitted on a double-red light. Intersections with this configuration are quite common in
Saskatoon Saskatoon () is the largest city in the Provinces and territories of Canada, Canadian province of Saskatchewan. It straddles a bend in the South Saskatchewan River in the central region of the province. It is located along the Trans-Canada Hig ...
,
Calgary Calgary () is a major city in the Canadian province of Alberta. As of 2021, the city proper had a population of 1,306,784 and a metropolitan population of 1,481,806 making it the third-largest city and fifth-largest metropolitan area in C ...
, and
Edmonton Edmonton is the capital city of the Provinces and territories of Canada, Canadian province of Alberta. It is situated on the North Saskatchewan River and is the centre of the Edmonton Metropolitan Region, which is surrounded by Central Alberta ...
. According to Transportation Alberta, there is no legal significance to a double red light. In some cities in
Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
, the double red light is treated as a standard red signal; the double light is used to increase the signal's visibility, as well as to provide a redundant light in case one fails.


Clock-type

These so-called "Heuer-Ampeln", developed by the German Heuer-Hammer company were used in the Netherlands, Austria (Vienna) and Germany from the 1930s until the 1960s, with the last of them being replaced with the by then common known traffic lights in 1972.


Bar signals

In Tianjin, one system is where there is a horizontal bar in a specific colour, with the colour changing and the bar shrinking. The shrinking bar indicates the time remaining in that colour. The colour itself is either red (stop), yellow or green (go). A blinking green one-third-full bar means "reduce speed now", and a blinking yellow full bar indicates "proceed with caution". When lights of this system turn from green to red, the diminishing green bar will flash once two-thirds (note: not the full bar) of the green bar is "eaten up", with the remaining third intact. A full, uninterrupted yellow bar will appear for a few seconds before, after a short blink, lights turn red. Immediately after the full red bar appears, a tiny (almost unnoticeable) split/division appears to signify the bit that will ''not'' be "eaten up". This corresponds to the usual position of a red light (leftmost, or rightmost if at the other end of the road and at the other side of the pavement; or the upper third). When two-thirds of the red bit is "eaten up", the red light extinguishes, only to be replaced nearly immediately with a full chunk of green (again with the minute division). The process then repeats itself.


Multi-colour aspects

Another system, which is also common in the other cities in China, is where there is a set of three lights as traffic lights. Every light is an arrow pointing in a different direction and every arrow has a colour of its own, to show whether traffic flow is permitted or prohibited in that direction. The major disadvantage of this system of traffic light is that it is unfamiliar to those who are used to seeing specific colours of the traffic lights at the various ends of a normal traffic light itself (e.g. green rightmost, red leftmost, etc.) as well is being problematic for the color blind (although by Chinese traffic laws, people who are color blind are not permitted to drive). It does, however, conserve space. The other disadvantage of it is it does not have indication of when a turn can be made without yielding and when the turn can made only after yielding to the oncoming traffic. Although by Chinese traffic laws, turning is always supposed to be made after yielding to oncoming traffic. Elsewhere in China, a blinking green light means "reduce speed now", attempting to stop cars from passing (if that car can still safely stop in time) and is nearly universal in appearance. Some cities or parts of cities show the number of seconds remaining in a specific traffic light colour (a so-called "countdown meter"). Another type of signal that can be found in China is the Unilight signal that displays all three colours in one signal section. Installation of this signal outside of China is banned by the
Vienna Convention on Road Signs and Signals The Convention on Road Signs and Signals, commonly known as the Vienna Convention on Road Signs and Signals, is a multilateral treaty to standardize the signing system for road traffic (road signs, traffic lights and road markings) in use inte ...
. The European Annex also even contains an explicit ban on it; so installation of multi-coloured aspects as traffic signals is prohibited.


Middle Section Lights

In the UK, at Aylesford near Maidstone, a set of middle section lights exist for traffic entering from their home driveways, as these are located on the narrow road between the traffic lights. Each light has a no left turn and a no right turn sign, which light up to indicate to drivers where not to turn so they don't turn into oncoming traffic. When no traffic on the road is coming, both no turn lights would light up.


Ramp meters

A
ramp meter A ramp meter, ramp signal, or metering light is a device, usually a basic traffic light or a two-section signal light (red and green only, no yellow) together with a signal controller, that regulates the flow of traffic entering freeways accordi ...
or metering light is a device, usually a basic
traffic light Traffic lights, traffic signals, or stoplights – also known as robots in South Africa, Zambia, and Namibia – are signaling devices positioned at intersection (road), road intersections, pedestrian crossings, and other locations in order t ...
or a two-phase (red and green, no yellow) light, that regulates the flow of traffic entering
freeways A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway, and expressway. Other similar terms ...
according to current traffic conditions. They are intended to reduce congestion on the freeway in two ways. One is to ensure that the total flow entering the freeway does not exceed the capacity at a downstream bottleneck. A second is to break up platoons of vehicles entering freeways, ensuring that traffic can merge more easily. Some metered ramps have bypass lanes for
high-occupancy vehicle A high-occupancy vehicle lane (also known as an HOV lane, carpool lane, diamond lane, 2+ lane, and transit lane or T2 or T3 lanes) is a restricted traffic lane reserved for the exclusive use of vehicles with a driver and at least one passenger, i ...
s, allowing car-poolers and
buses A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a motor vehicle that carries significantly more passengers than an average car or van, but fewer than the average rail transport. It is most commonly used ...
to skip the queue and get directly on the highway. Meters often only operate in
rush hour A rush hour (American English, British English) or peak hour (Australian English, Indian English) is a part of the day during which traffic congestion on roads and crowding on public transport is at its highest. Normally, this happens twice e ...
periods. On some large toll bridges, such as the
San Francisco–Oakland Bay Bridge The San Francisco–Oakland Bay Bridge, commonly referred to as the Bay Bridge, is a complex of bridges spanning San Francisco Bay in California. As part of Interstate 80 in California, Interstate 80 and the direct road between San Francisco an ...
, red/green traffic lights, similar to ramp meters, are used to stagger traffic leading onto the bridge. At the Bay Bridge, about 25 lanes of
toll booth A tollbooth (or toll booth) is an enclosure placed along a toll road that is used for the purpose of collecting a toll from passing traffic. A structure consisting of several tollbooths placed next to each other is called a toll plaza, tollga ...
traffic are reduced to five lanes of bridge traffic in about mile (800 metres). To accomplish this, an overhead red/green traffic light is visible above each lane, several hundred feet beyond the toll plaza. Green is illuminated for two seconds, signalling the first driver in that lane to begin acceleration. Then the signal jumps to red for eight seconds. Using this method, there are always five lanes with a "green" signal, staggered throughout the 25 lanes of traffic.


Timers at signals

Traffic lights are sometimes accompanied by timers that indicate how much longer a certain phase will last. This is especially common for pedestrian crossing lights in high-traffic areas. Although prohibited for vehicular traffic in most countries around the world, timers have been extensively used in
Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
,
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
,
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...
,
China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...
,
Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...
,
Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...
,
Cambodia Cambodia, officially the Kingdom of Cambodia, is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. It is bordered by Thailand to the northwest, Laos to the north, and Vietnam to the east, and has a coastline ...
and
Vietnam Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of mainland Southeast Asia, with an area of about and a population of over 100 million, making it the world's List of countries and depende ...
for both pedestrian and vehicular traffic but in
Vietnam Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of mainland Southeast Asia, with an area of about and a population of over 100 million, making it the world's List of countries and depende ...
, they are rarely used for pedestrians. A major disadvantage of this is that timers can only be used when the traffic lights are under fixed-time operation, reducing flexibility. This is because it is otherwise impossible to know for exactly how long the light will be green or red. In Canada and the US, most pedestrian signals now have countdown timers in the flashing hand symbol/"Don't Walk" phase. All new installations of pedestrian signals in the US must include a countdown timer, unless the countdown timer is less than seven seconds long, per the 2009 MUTCD. In
New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...
, however, this is not the case, as only streets that are wide enough will get countdown timers, regardless of the length of the countdown. Countdown pedestrian signals are also used in a few places in
London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...
and Manchester, England. In some cities (such as
Newberg, Oregon Newberg is a city in Yamhill County, Oregon, Yamhill County, Oregon, United States. Located in the Portland metropolitan area, the city is home to George Fox University. As of 2023 the city population was 26,095 making it the second most populous ...
;
Kyiv Kyiv, also Kiev, is the capital and most populous List of cities in Ukraine, city of Ukraine. Located in the north-central part of the country, it straddles both sides of the Dnieper, Dnieper River. As of 1 January 2022, its population was 2, ...
,
Ukraine Ukraine is a country in Eastern Europe. It is the List of European countries by area, second-largest country in Europe after Russia, which Russia–Ukraine border, borders it to the east and northeast. Ukraine also borders Belarus to the nor ...
; Burghausen,
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
and
Kraków , officially the Royal Capital City of Kraków, is the List of cities and towns in Poland, second-largest and one of the oldest cities in Poland. Situated on the Vistula River in Lesser Poland Voivodeship, the city has a population of 804,237 ...
,
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...
) there are signs displaying how fast one has to drive in order to reach the next intersection at the exact time when the light turns green, thus allowing the driver to ease into a
green wave A green wave occurs when a series of traffic lights (usually three or more) are coordinated to allow continuous traffic flow over several Intersection (road), intersections in one main direction. Any vehicle traveling along with the green wave ( ...
.


See also

*
Traffic light Traffic lights, traffic signals, or stoplights – also known as robots in South Africa, Zambia, and Namibia – are signaling devices positioned at intersection (road), road intersections, pedestrian crossings, and other locations in order t ...
*
Traffic light control and coordination The normal function of traffic lights requires more than sight control and coordination to ensure that traffic and pedestrians move as smoothly, and safely as possible. A variety of different control systems are used to accomplish this, ranging f ...


References


External links


Left-turn Signal Display Animation Page
adapted fro
Evaluation of Traffic Signal Displays for Protected/Permitted Left-Turn Control
(Report 493, 2003) by the
National Cooperative Highway Research Program The National Cooperative Highway Research Program (NCHRP) conducts research in problem areas that affect highway planning, design, construction, operation, and maintenance in the United States. Spearheaded by the Transportation Research Board (TR ...
{{DEFAULTSORT:List Of Variations In Traffic Light Signalling And Operation Pedestrian crossing components Traffic law Traffic signals