Traffic comprises pedestrians, vehicles, ridden or herded animals, trains, and other conveyances that use public ways (roads/sidewalks) for travel and transportation.
A roundabout, also known as a rotary or traffic circle, 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.
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. In a more general sense, levels of service can apply to all services in asset management domain.
A Michigan left or P-turn is an at-grade intersection design that replaces each left (farside) turn at an intersection between a (major) divided roadway and a secondary (minor) roadway with the combination of a right (nearside) turn followed by a U-turn, or a U-turn followed by a right (nearside) turn, depending on the situation. It is in use in numerous countries.
In road transport, a lane is part of a roadway that is designated to be used by a single line of vehicles to control and guide drivers and reduce traffic conflicts. Most public roads (highways) have at least two lanes, one for traffic in each direction, separated by lane markings. On multilane roadways and busier two-lane roads, lanes are designated with road surface markings. Major highways often have two multi-lane roadways separated by a median.
A single-point urban interchange, also called a single-point interchange (SPI) or single-point diamond interchange (SPDI), is a type of highway interchange. The design was created in order to help move large volumes of traffic through limited amounts of space safely and efficiently.
A superstreet, also known as a restricted crossing U-turn (RCUT), J-turn, or reduced conflict intersection (RCI), is a type of road intersection that is a variation of the Michigan left. In this configuration, in contrast to the Michigan left, traffic on the minor road is not permitted to proceed straight across the major road or highway. Drivers on the minor road wishing to turn left or go straight must turn right onto the major road, then, a short distance away, queue (wait) into a designated U-turn lane in the median. When traffic clears, they complete the U-turn and then either go straight or make a right turn when they intersect the other half of the minor road.
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 diverging diamond interchange (DDI), also called a double crossover diamond interchange (DCD), is a subset of diamond interchange in which the opposing directions of travel on the non-freeway road cross each other on either side of the interchange so that traffic crossing the freeway on the overpass or underpass is operating on the opposite driving side from that which is customary for the jurisdiction. The crossovers may employ one-side overpasses or be at-grade and controlled by traffic light.
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, how long the pedestrian WALK signal should be, whether trains or buses should be prioritized, and numerous other factors.
A junction is where two or more roads meet.
A road is a thoroughfare, route, or way on land between two places that has been surfaced or otherwise improved to allow travel by foot or some form of conveyance, including a motor vehicle, cart, bicycle, or horse. Roads have been adapted to a large range of structures and types in order to achieve a common goal of transportation under a large and wide range of conditions. The specific purpose, mode of transport, material and location of a road determine the characteristics it must have in order to maximize its usefulness. Following is one classification scheme.
Vehicle infrastructure integration (VII) is an initiative fostering research and application development for a series of technologies directly linking road vehicles to their physical surroundings, first and foremost to improve road safety. The technology draws on several disciplines, including transport engineering, electrical engineering, automotive engineering, and computer science. VII specifically covers road transport, although similar technologies are in place or under development for other modes of transport. Planes, for example, use ground-based beacons for automated guidance, allowing the autopilot to fly the plane without human intervention. In highway engineering, improving the safety of a roadway can enhance overall efficiency. VII targets improvements in both safety and efficiency.
A seagull intersection or continuous green T-intersection is a type of three-way road intersection, usually used on high traffic volume roads and dual carriageways. This form of intersection is popular in Australia and New Zealand, and sometimes used in the United States and other countries.
Channelization is a traffic engineering concept that 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 crashes 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.
Urban freight distribution is the system and process by which goods are collected, transported, and distributed within urban environments. The urban freight system can include seaports, airports, manufacturing facilities, and warehouse/distribution centers that are connected by a network of railroads, rail yards, pipelines, highways, and roadways that enable goods to get to their destinations.
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.
A managed lane is a type of highway lane that is operated with a management scheme, such as lane use restrictions or variable tolling, to optimize traffic flow, vehicle throughput, or both. Definitions and goals vary among transport agencies, but managed lanes are generally implemented to achieve an improved operational condition on a highway, such as improving traffic speed and throughput, reducing air pollution, and improving safety. Types of managed lanes include high-occupancy vehicle (HOV) lanes, high-occupancy toll lanes, express toll lanes, reversible lanes, and bus lanes. Most managed lane facilities are located in the United States and Canada, although HOV and bus lanes can be found in many other countries; outside of the US and Canada, many countries use active traffic management that manage all lanes of a highway.
A stroad is a type of thoroughfare that is a mix between a street and a road. Common in the United States and Canada, stroads are wide arterials that often provide access to strip malls, drive-throughs, and other automobile-oriented businesses. Urban planners have criticized stroads for their safety issues and poor efficiency. While streets provide access to shops and residences at safe traffic speeds, and roads can efficiently move traffic at high speed and volume, stroads pose dangers to drivers and pedestrians and are also prone to congestion.
