Channelization (roads)

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Channelization is an engineering concept which employs the use of secondary roads to separate certain flows of traffic from the main traffic lanes. This method came into favor in the United States in the 1950s. One of the most effective and efficient methods of controlling the traffic on a highway is the adoption of high intersection geometric design standards. Channelization is an integral part of at grade intersections and is used to separate turning movements from through movements where this is considered advisable and hence helps reduce the intensity and frequency of loss of life and property due to accidents to a large extent. Proper Channelization increases capacity, improves safety, provides maximum convenience, and instils driver confidence. Improper Channelization has the opposite effect and may be worse than none at all. Over Channelization should be avoided because it could create confusion and worsen operations. Channelization of at-grade intersections is the separation or regulation of conflicting traffic movements into definite paths of travel by the use of pavement markings, raised islands, or other suitable means to facilitate the safe and orderly movement of both vehicles and pedestrians.

Traffic engineering (transportation) branch of civil engineering

Traffic engineering is a branch of civil engineering that uses engineering techniques to achieve the safe and efficient movement of people and goods on roadways. It focuses mainly on research for safe and efficient traffic flow, such as road geometry, sidewalks and crosswalks, cycling infrastructure, traffic signs, road surface markings and traffic lights. Traffic engineering deals with the functional part of transportation system, except the infrastructures provided.

Intersection (road) A road junction where two or more roads either meet or cross at grade

An intersection is an at-grade junction where two or more roads meet or cross. Intersections may be classified by number of road segments, traffic controls, and/or lane design.

Pedestrian person traveling on foot

A pedestrian is a person travelling on foot, whether walking or running. In some communities, those travelling using tiny wheels such as roller skates, skateboards, and scooters, as well as wheelchair users are also included as pedestrians. In modern times, the term usually refers to someone walking on a road or pavement, but this was not the case historically.

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Roundabout Traffic intersection

A roundabout 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.

Level of service (LOS) is a qualitative measure used to relate the quality of motor vehicle traffic service. LOS is used to analyze roadways and intersections by categorizing traffic flow and assigning quality levels of traffic based on performance measure like vehicle speed, density, congestion, etc.

The American Association of State Highway and Transportation Officials (AASHTO) is a standards setting body which publishes specifications, test protocols and guidelines which are used in highway design and construction throughout the United States. Despite its name, the association represents not only highways but air, rail, water, and public transportation as well.

Diamond interchange common type of road junction

A diamond interchange is a common type of road junction, used where a freeway crosses a minor road.

Federal Highway Administration government agency

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 and the Federal Lands Highway Program. Its role had previously been performed by the Office of Road Inquiry, Office of Public Roads and the Bureau of Public Roads.

Right-in/right-out

Right-in/right-out (RIRO) and left-in/left-out (LILO) refer to a type of three-way road intersection where turning movements of vehicles are restricted. A RIRO permits only right turns and a LILO permits only left turns. "Right-in" and "left-in" refer to turns from a main road into an intersection ; "right-out" and "left-out" refer to turns from an intersection to a main road. RIRO is typical when vehicles drive on the right, and LILO is usual where vehicles drive on the left. This is because minor roads usually connect to the outsides of two-way roads. However, on a divided highway, both RIRO and LILO intersections can occur.

A junction is where two or more roads meet.

Gilberts Corner, Virginia Unincorporated area in Virginia

Gilberts Corner is an unincorporated area at the intersection of U.S. Route 50 and U.S. Route 15 in Loudoun County, Virginia located in Aldie, east of the historic Village of Aldie.

Access management, when used in traffic and traffic engineering circles, generally refers to the regulation of interchanges, intersections, driveways and median openings to a roadway. Its objectives are to enable access to land uses while maintaining roadway safety and mobility through controlling access location, design, spacing and operation. This is particularly important for major roadways intended to provide efficient service to through-traffic movements.

Quadrant roadway intersection

A quadrant roadway intersection adds an additional "quadrant roadway" between two legs of an intersection. This roadway adds two three-way intersections in addition to the original four-way intersection moving all left turns or right turns from the main intersection. The design is intended to improve traffic flow by reducing signal timing phases from four to two in the main intersection. The design is intended for intersections where large artery routes meet in an area of dense development and high pedestrian volume.

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.

Highway Capacity Manual federal highway manual

The Highway Capacity Manual (HCM) is a publication of the Transportation Research Board of the National Academies of Science 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, signalized and unsignalized intersections, rural highways, and the effects of mass transit, pedestrians, and bicycles on the performance of these systems.

Geometric design of roads

The geometric design of roads is the branch of highway engineering concerned with the positioning of the physical elements of the roadway according to standards and constraints. The basic objectives in geometric design are to optimize efficiency and safety while minimizing cost and environmental damage. Geometric design also affects an emerging fifth objective called "livability," which is defined as designing roads to foster broader community goals, including providing access to employment, schools, businesses and residences, accommodate a range of travel modes such as walking, bicycling, transit, and automobiles, and minimizing fuel use, emissions and environmental damage.

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 (TRB), it is jointly supported by federal agencies, state departments of transportation, and other nonprofit organizations.

Sidra Intersection is a software package used for intersection (junction) and network capacity, level of service and performance analysis, and signalised intersection and network timing calculations by traffic design, operations and planning professionals.

Glossary of road transport terms Wikimedia list article

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.

Offset T-intersection

An offset T-intersection is an at-grade road intersection where a conventional four leg intersection is split into two three-leg T-intersections to reduce the number of conflicts and improve traffic flow. Building the offset T-intersections as continuous green T-intersections, there is a single stop on the arterial road, only. A higher volume of through traffic on the cross road, or on unsignalized intersections, a rebuild to a conventional four-leg intersection may be adequate, also when the offset is a few feet only like staggered junctions causing slower traffic for a longer time on the arterial road.

Split intersection

A split intersection is a rarely built at-grade variant of the diamond interchange. Compared to a conventional four-leg intersection or road crossing, the arterial road is split into separate carriageways by 200 to 300 feet, allowing a queue of left turning vehicles behind a completed turn into the crossroad without any conflict to oncoming traffic. On the crossroad, the four leg intersection is being replaced by two intersections. The beginning one-way traffic at the fourth leg makes the intersections reduce the number of conflicts similar to a three leg T-intersection to improve traffic flow.

References

The Transportation Research Board (TRB) is a division of the National Research Council of the United States which serves as an independent adviser to the President of the United States, the Congress and federal agencies on scientific and technical questions of national importance. It is jointly administered by the National Academy of Sciences, the National Academy of Engineering, and the National Academy of Medicine.

International Standard Book Number Unique numeric book identifier

The International Standard Book Number (ISBN) is a numeric commercial book identifier which is intended to be unique. Publishers purchase ISBNs from an affiliate of the International ISBN Agency.