A green wave occurs when a series of traffic lights (usually three or more) are coordinated to allow continuous traffic flow over several intersections in one main direction.
Any vehicle traveling along with the green wave (at an approximate speed decided upon by the traffic engineers) will see a progressive cascade of green lights, and not have to stop at intersections. This allows higher traffic loads, and reduces noise and energy use (because less acceleration and braking is needed). In practical use, only a group of cars (known as a "platoon", the size of which is defined by the signal times) can use the green wave before the time band is interrupted to give way to other traffic flows.
The coordination of the signals is sometimes done dynamically, according to sensor data of currently existing traffic flows - otherwise it is done statically, by the use of timers. Under certain circumstances, green waves can be interwoven with each other, but this increases their complexity and reduces usability, so in conventional set-ups only the roads and directions with the heaviest loads get this preferential treatment.
In 2011, a study modeled the implementation of green waves during the night in a busy Manchester suburb (Chorlton-cum-Hardy) using S-Paramics microsimulation and the AIRE emissions module. [1] The results showed using green wave signal setups on a network have the potential to:
A green wave in both directions may be possible with different speed recommendations for each direction, otherwise traffic coming from one direction may reach the traffic light faster than from the other direction if the distance from the previous traffic light is not mathematically a multiple of the opposite direction. Alternatively a dual carriageway may be suitable for green waves in both directions if there is sufficient space in the central reservation to allow pedestrians to wait and separate pedestrian crossing stages for each side of the road. [1]
Green waves are sometimes used to facilitate bicycle traffic. Copenhagen, [4] Amsterdam, [5] San Francisco, [6] and other cities may synchronize traffic signals to provide a green light for a flow of cyclists. On San Francisco's Valencia Street, the signals were retimed in early 2009 to provide a green wave in both directions, possibly the first street in the world with a two-way green wave for cyclists. In Copenhagen, a green wave on the arterial street Nørrebrogade facilitates 30,000 cyclists to maintain a speed of 20 km/h (12 mph) for 2.5 km (1.6 mi). In Amsterdam, cyclists riding at a speed of 15 to 18 km/h (9.3 to 11.2 mph) will be able to travel without being stopped by a red signal. Tests show that public transport can benefit as well and cars may travel slightly slower.
In Vienna, Austria a stretch of cycle path on Lassallestraße in the 2nd district has a display that tells cyclists their speed and the speed they must maintain to make the next green light.
Frederiksberg, a part of Copenhagen, the capital of Denmark, has implemented a green wave for emergency vehicles to improve the public services.
In the UK, in 2009, it was revealed that the Department for Transport had previously discouraged green waves as they reduced fuel usage, and thus less revenue was raised from fuel taxes. [7] [8] Despite this government Webtag documents were only updated in 2011. It is still unclear if the economic appraisal software used to apply these guidelines has also been updated and if the new guidelines are being applied to new projects.
In a more limited sense, the term Green wave has also been applied to railroad travel. For several years starting in the 1960s, the German Federal Railway maintained an advertising campaign featuring the slogan German: garantiert grüne Welle, lit. 'Guaranteed Green Wave', which communicated the notion of speed, limited delays and open track blocks to potential customers choosing between train and automobile travel, and was featured prominently in promotional materials ranging from posters to radio jingles.
Traffic comprises pedestrians, vehicles, ridden or herded animals, trains, and other conveyances that use public ways (roads) for travel and transportation.
A roundabout, also known as a rotary or traffic circle or rotunda, is a type of circular intersection or junction in which road traffic is permitted to flow in one direction around a central island, and priority is typically given to traffic already in the junction.
An intersection or an at-grade junction is a junction where two or more roads converge, diverge, meet or cross at the same height, as opposed to an interchange, which uses bridges or tunnels to separate different roads. Major intersections are often delineated by gores and may be classified by road segments, traffic controls and lane design.
Traffic lights, traffic signals, or stoplights – also known as robots in South Africa – are signalling devices positioned at road intersections, pedestrian crossings, and other locations in order to control the flow of traffic.
A hook turn or two-stage turn, also known as a Copenhagen Left, is a road cycling manoeuvre or a motor vehicle traffic-control mechanism in which vehicles that would normally turn from the innermost lane of an intersection instead turn from the outermost lane, across all other lanes of traffic.
Road signs in the United Kingdom and in its associated Crown dependencies and overseas territories conform broadly to European design norms, though a number of signs are unique: direction signs omit European route numbers and road signs generally use the Imperial System of units, unlike the rest of Europe. Signs in Wales and parts of Scotland are bilingual.
Road signs in Sweden are regulated in Vägmärkesförordningen, VMF (2007:90), and are to be placed 2 metres from the road with the sign 1.6 m from the base for motorized roads. Except for route numbers, there are a maximum of three signs on a pole, with the most important sign at the top. All signs have a reflective layer added on selected parts of the sign as is custom in European countries; most larger signs also have their own illumination.
In traffic engineering, there are regional and national variations in traffic light operation. This may be in the standard traffic light sequence or by the use of special signals.
An all-way stop – also known as a four-way stop – is a traffic management system which requires vehicles on all the approaches to a road intersection to stop at the intersection before proceeding through it. Designed for use at low traffic-volume locations, the arrangement is common in the United States, Canada, Mexico, South Africa, and Liberia, as well as in a number of, usually rural, locations in Australia where visibility on the junction approaches is particularly poor. The stop signs at such intersections may be supplemented with additional plates stating the number of approaches.
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 from simple clockwork mechanisms to sophisticated computerized control and coordination systems that self-adjust to minimize delay to people using the junction.
Cycling infrastructure is all infrastructure cyclists are allowed to use. Bikeways include bike paths, bike lanes, cycle tracks, rail trails and, where permitted, sidewalks. Roads used by motorists are also cycling infrastructure, except where cyclists are barred such as many freeways/motorways. It includes amenities such as bike racks for parking, shelters, service centers and specialized traffic signs and signals. The more cycling infrastructure, the more people get about by bicycle.
Road signs in Switzerland and Liechtenstein generally conform to the 1968 Vienna Convention on Road Signs and Signals.
Road signs in Hong Kong are standardised by the Transport Department. Due to being a former British territory, the road signage in Hong Kong is similar to road signs in the United Kingdom, with the addition of Traditional Chinese characters.
A protected intersection or protected junction, also known as a Dutch-style junction, is a type of at-grade road junction in which cyclists and pedestrians are separated from cars. The primary aim of junction protection is to help pedestrians and cyclists be and feel safer at road junctions.
Terminology related to road transport—the transport of passengers or goods on paved routes between places—is diverse, with variation between dialects of English. There may also be regional differences within a single country, and some terms differ based on the side of the road traffic drives on. This glossary is an alphabetical listing of road transport terms.
Road signs in Lithuania ensure that transport vehicles move safely and orderly, as well as to inform the participants of traffic built-in graphic icons. These icons are governed by the Vienna Convention on Road Traffic and Vienna Convention on Road Signs and Signals.
Road signs in Russia ensure that transport vehicles move safely and orderly, as well as to inform the participants of traffic built-in graphic icons. These icons are governed by the Vienna Convention on Road Traffic and Vienna Convention on Road Signs and Signals. Similar road signs are also used in other post-Soviet countries.
This page lists the traffic signs used in Belgium, as included in the traffic code.
The United Kingdom has specific types of pedestrian crossing.
Road signs in Latvia ensure that transport vehicles move safely and orderly, as well as to inform the participants of traffic built-in graphic icons. These icons are governed by the Vienna Convention on Road Traffic and Vienna Convention on Road Signs and Signals. The system is covered in Ceļu satiksmes noteikumi and the standards documents LVS 77–1:2016 "Ceļa zīmes. 1. daļa: Ceļa zīmes", LVS 77-2:2016 "Ceļa zīmes. 2. daļa: Uzstādīšanas noteikumi" and LVS 77-3:2016 "Ceļa zīmes. 3. daļa: Tehniskās prasības".
Recently the first 'green wave' bike route has been inaugurated to the satisfaction of 30,000 cyclists, who use the bike lane on one of Copenhagen's busiest streets, Nørrebrogade.