Green wave

Green Wave may refer to: *Green wave, a series of traffic lights coordinated to allow continuous traffic flow in one main direction *The Green Wave, a 2010 documentary film directed by Iranian-German Ali Samadi Ahadi *Green Wave (radio show), a Vietnamese music chart programme *The Green Wave, an 1866 painting by Claude Monet *Green Wave (abortion rights), a group of abortion-rights activists in the Americas *"Green Wave", a cultivar of the polypodium fern *Green Wave, a preservationist group, organized by Russian singer and actor Mikhail Novitsky *Greenwave, a mass science experiment involving primary schools across Ireland *GreenWave, an aquaculture non-profit in North America *Green Wave (Malaysia), a political phenomenon in Malaysia

A green wave or platoon effect 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. t_{ideal} = \frac{L}{S} where: t_{ideal} = ideal offset L = distance between two signalized intersections S = average platoon speed However, the ideal situation assumes no downstream queues, which may occur when not all vehicles from the previous platoon clear through the red signal ("stragglers"), and when vehicles from outside the subject road enter the traffic. As a result, an adjustment to the offset is made: t_{adjust} = t_{ideal} - (Qh + l_{1}) = \frac{L}{S} - (Qh + l_{1}) where: t_{adjust} = adjusted ideal offset, in seconds Q = number of vehicles queued per lane h = discharge headway of queued vehicles, in seconds per vehicle l_{1} = start-up lost time, in seconds As a result of this adjustment, the signal's "green wave" is progressing faster than the vehicles' arriving platoon to pick up queued vehicles. Bandwidth, defined as time difference between the first vehicle can pass through the entire system nonstop and the last vehicle can do the same, is essentially a "green window" that follows the platoon. Bandwidth efficiency, defined as the ratio of bandwidth to the system's cycle length, is calculated as such: EFF_{BW} = \frac{BW}{C} where: EFF_{BW} = bandwidth efficiency, in percentage (%) BW = bandwidth, in seconds C = cycle length, in seconds A good bandwidth efficiency is between 40 - 55%. Bandwidth capacity, defined as vehicles that can pass through signals without stopping, is calculated as such: c_{BW} = \frac{3600 (sec/hr) \times BW \times L}{C \times h} where: c_{BW} = bandwidth capacity, in vehicle per hour BW = bandwidth, in seconds L = number of through lanes in the subject direction C = cycle length, in seconds h = saturation headway, time difference between two adjacent vehicles in a queue passing through green lights, in seconds per vehicle n \times C = t_{12} + t_{21} where: n = an integer ≥ 1 C = cycle length, in seconds t_{12} = offset for the traffic direction traveling from intersection 1 to intersection 2, in seconds t_{21} = offset for the traffic direction traveling from intersection 2 to intersection 1, in seconds For a grid of a one-way streets, such as a simple square-shaped grid going from intersection 1, to intersection 2, to intersection 3, to intersection 4, and back to intersection 1, the formula may be expressed as such: n \times C = t_{12} + g_{2}+t_{23} + g_{3}+t_{34} + g_{4}+t_{41} + g_{1} where: n = an integer ≥ 1 C = cycle length, in seconds t_{ij} = offset for the traffic direction traveling from intersection i to intersection j , in seconds g_{i} = green time at intersection i , in seconds

Further reading

Text derived from https://en.wikipedia.org/w/index.php?oldid=1177602579 under CC BY-SA 4.0; modifications have been made.