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 according to current traffic conditions. Ramp meters are used at freeway on-ramps to manage the rate of automobiles entering the freeway. Ramp metering systems have proved to be successful in decreasing traffic congestion and improving driver safety.
Ramp meters are claimed to reduce congestion (increase speed and volume) on freeways by reducing demand and by breaking up platoons of cars. Two variations of demand reduction are commonly cited; one being access rate, the other diversion. Some ramp meters are designed and programmed to operate only at times of peak travel demand; during off-peak times, such meters are either showing a steady green, flashing yellow (Maryland), or are turned off altogether. This allows traffic to merge onto the freeway without stopping. Other ramp meters are designed to operate continuously, only being turned off for maintenance or repairs.
Some metered ramps have bypass lanes for high-occupancy vehicles, allowing carpoolers, buses, and other eligible vehicles to skip the queue and get directly on the highway. In other places such as Northern California, carpool lanes are still metered, but the queue is typically shorter in comparison to regular lanes. Meters often only operate in rush hour periods. Some ramp meters have only one lane of traffic at the signal; others may have two or more lanes of traffic. Generally, meters with multiple lanes only give one lane the green light at a time. In one common configuration, each entrance lane has two signals; a red-yellow-green signal perched overhead over each lane (or mounted high on a pole for a single lane), and a two-phase lamp mounted low on a pole next to the stop line.
The overhead lights are for cars approaching the metering point; the low-mounted two-phase lights are intended to be used by the vehicle at the front of the queue.
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Introduce the major elements of transportation systems and traffic engineering-Develop analytical and technical skills in applying the fundamentals of the transport field-Understand the key concepts a
The objectives of this course are to present the major elements of traffic operations and to develop basic skills in applying the fundamentals of traffic analysis and control. Students should be able
Learn how to describe, model and control urban traffic congestion in simple ways and gain insight into advanced traffic management schemes that improve mobility in cities and highways.
Learn how to describe, model and control urban traffic congestion in simple ways and gain insight into advanced traffic management schemes that improve mobility in cities and highways.
vignette|alt=Une autoroute en Allemagne|L’autoroute allemande caractérisée par une vitesse libre sur les deux tiers de son kilomètrage (A20), dotée d'un terre-plein central enherbé à deux glissières de sécurité, de deux bandes d’arrêt d’urgence, et de larges talus enherbés limités par une clôture limitant le risque de collisions accidentelles avec de grands animaux. vignette|Autoroute en Autriche permettant un passage rapide des Alpes, par des ponts et tunnels.
vignette|Embouteillage à Los Angeles en 1953. Un embouteillage (« bouchon » ou « file » en Europe, « congestion » au Canada) est un encombrement de la circulation, généralement automobile, réduisant fortement la vitesse de circulation des véhicules sur la voie. right|thumb|Les départs ou les retours de vacances sont une des sources d'embouteillage (Algarve, Portugal, été 2005). Les mots embouteillage, bouchon et congestion (également utilisé en anglais) sont utilisés par analogie, tous ces mots étant auparavant employés dans d'autres domaines.
vignette|Le BHNS d'Aix, circulant en site propre (ici sa voie propre) à Aix-en-Provence Site (transports en commun) thumb|Contre-exemple de site partagé entre bus, taxis et deux-roues, véhicules d'urgence à Mannheim, en Allemagne. Un transport collectif en site propre (TCSP) est un transport en commun qui emprunte une voie ou un espace qui lui est réservé, de telle manière que ce mode de transport dispose de sa propre voie, son propre site, de façon à garantir une priorité sur le trafic automobile et permettre ainsi un gain de temps.
The pNEUMA dataset is the result of a unique field experiment using a swarm of ten drones flying over the central district of Athens, Greece. Using this newly available dataset, this paper focuses on two directly related topics: i) lane changing and ii) la ...
The goal of this thesis is to analyze lane changes and lane choice in a congested urban envi- ronment. This is possible thanks to the pNEUMA dataset, a new trac dataset resulting from a eld experiment with 10 drones ying over the central district of Athen ...
Pedestrians, like drivers, generally dislike congestion. This is true for most pedestrian environments: trains stations, airports, or shopping malls. Furthermore, pedestrian congestion also influences the attractiveness of public transportation networks. T ...