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Intersection Capacity Utilization
Intersection Capacity Utilization (ICU) method is a tool for measuring a roadway intersection's capacity. It is ideal for transportation planning applications such as roadway design, congestion management programs and traffic impact studies. It is not intended for traffic operations or signal timing design. ICU is also defined as "the sum of the ratios of approach volume divided by approach capacity for each leg of intersection which controls overall traffic signal timing plus an allowance for clearance times." The ICU tells how much reserve capacity is available or how much the intersection is overcapacity. The ICU does not predict delay, but it can be used to predict how often an intersection will experience congestion. The method by which the ICU is used shows what the ICU is about. The ICU uses a grading system to rank the intersection that is being studied. This ranking system is known as the Level of Service (LOS) for the intersection. ICU is timing plan independent, yet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intersection (road)
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. Types Road segments One way to classify intersections is by the number of road segments (arms) that are involved. * A three-way intersection is a junction between three road segments (arms): a T junction when two arms form one road, or a Y junction, the latter also known as a fork if approached from the stem of the Y. * A four-way intersection, or crossroads, usually involves a crossing over of two streets or roads. In areas where there are blocks and in some other cases, the crossing streets or roads are perpendicular to each other. However, two roads may cross at a different angle. In a few cases, the junction of two road segments ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transportation
Transport (in British English), or transportation (in American English), is the intentional movement of humans, animals, and goods from one location to another. Modes of transport include air, land (rail and road), water, cable, pipeline, and space. The field can be divided into infrastructure, vehicles, and operations. Transport enables human trade, which is essential for the development of civilizations. Transport infrastructure consists of both fixed installations, including roads, railways, airways, waterways, canals, and pipelines, and terminals such as airports, railway stations, bus stations, warehouses, trucking terminals, refueling depots (including fueling docks and fuel stations), and seaports. Terminals may be used both for interchange of passengers and cargo and for maintenance. Means of transport are any of the different kinds of transport facilities used to carry people or cargo. They may include vehicles, riding animals, and pack animals. Vehicl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traffic Congestion
Traffic congestion is a condition in transport that is characterized by slower speeds, longer trip times, and increased vehicular queueing. Traffic congestion on urban road networks has increased substantially since the 1950s. When traffic demand is great enough that the interaction between vehicles slows the speed of the traffic stream, this results in some congestion. While congestion is a possibility for any mode of transportation, this article will focus on automobile congestion on public roads. As demand approaches the capacity of a road (or of the intersections along the road), extreme traffic congestion sets in. When vehicles are fully stopped for periods of time, this is known as a traffic jam or (informally) a traffic snarl-up. Traffic congestion can lead to drivers becoming frustrated and engaging in road rage. Mathematically, traffic is modeled as a flow through a fixed point on the route, analogously to fluid dynamics. Causes Traffic congestion occurs when ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signal Timing Design
Signal timing is the technique which traffic engineers use to distribute right-of-way at a signalized intersection. The process includes selecting appropriate values for timing, which are implemented in specialized traffic signal controllers. Signal timing involves deciding how much green time the traffic signal provides an intersection by movement or approach (depending on the lane configuration), how long the pedestrian WALK signal should be, whether trains or buses should be prioritized, and numerous other factors. Basic signal timing operation To understand basic signal timing fundamentals, one must also understand the different modes of operation of the signal controller which controls the signal. Traffic signals may be placed into two broad groups by their method of operation. They can be either pre-timed or actuated. Pre-timed signals provide each intersection approach a fixed amount of time on a predetermined basis, serving each approach consecutively, and repeating the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Level Of Service (SLA)
{{Disambiguation ...
Level of service may refer to: * Levels of service in asset management * Level of service (transportation) in transportation and traffic * Something agreed on in a Service-level agreement A service-level agreement (SLA) is a commitment between a service provider and a customer. Particular aspects of the service – quality, availability, responsibilities – are agreed between the service provider and the service user. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uncontrolled Intersections
An uncontrolled intersection is a road intersection where no traffic lights, road markings or signs are used to indicate the right-of-way. They are found in either residential neighborhoods or in rural areas. While the intersection itself is unmarked, warning signs or lights may be present to alert drivers to it. Uncontrolled T-intersection At an uncontrolled T-intersection (3-way intersection), right-of-way rules differ from country to country. In Australia, the United Kingdom, New Zealand and most of the United States, traffic on the terminating road must give way (yield) to traffic on the continuing road. In Germany, https://www.gesetze-im-internet.de/stvo/__8.html - in German - |
Highway Capacity Manual
The Highway Capacity Manual (HCM) is a publication of the Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine in the United States. It contains concepts, guidelines, and computational procedures for computing the capacity and quality of service of various highway facilities, including freeways, highways, arterial roads, roundabouts, traffic signal, signalized and uncontrolled intersection, unsignalized intersections, Interchange (road), interchanges, rural highways, and the effects of mass transit, pedestrians, and bicycles on the performance of these systems. There have been seven editions with improved and updated procedures from 1950 to 2022, and major updates to the HCM 1985 edition, in 1994, 1997 and 2015. Chapter 1 The HCM has been a worldwide reference for transportation and traffic engineering scholars and practitioners, and also the base of several country-specific capacity manuals. The most-recent version, the ''Highway Capa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methodology
In its most common sense, methodology is the study of research methods. However, the term can also refer to the methods themselves or to the philosophical discussion of associated background assumptions. A method is a structured procedure for bringing about a certain goal. In the context of research, this goal is usually to discover new knowledge or to verify pre-existing knowledge claims. This normally involves various steps, like choosing a sample, collecting data from this sample, and interpreting this data. The study of methods involves a detailed description and analysis of these processes. It includes evaluative aspects by comparing different methods to assess their advantages and disadvantages relative to different research goals and situations. This way, a methodology can help make the research process efficient and reliable by guiding researchers on which method to employ at each step. These descriptions and evaluations of methods often depend on philosophical background ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saturation (traffic)
In traffic engineering, saturation describes the maximum traffic flow which can be handled by a junction. The saturation flow is the rate at which a continuous flow of vehicles can pass through a constant green signal, typically expressed in vehicles per hour or PCUs per hour. A formula to calculate saturation flows based on lane geometry is given in Transport and Road Research Laboratory RR67. However, the formula can over-estimate saturation flows at congested locations. Degree of Saturation The degree of saturation (DoS) of an intersection (typically under traffic signal control) or a link measures the demand relative to the total capacity. A DoS value of 100% meaning that demand and capacity are equal and no further traffic is able to progress through the junction. The formula to calculate DoS is: *Degree of saturation = (demand x cycle time) / (saturation flow x effective green time) Values over 85%-90% typically indicate traffic congestion Traffic congestion is a con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
