Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
72 GLOSSARY acceleration lane: A speed-change lane, including tapered areas, that enables a vehicle entering a roadway to increase its speed to a rate that enables it to safely merge with through traffic. access category: A classification system for regulating access that is used to assign sets of access management standards to road- ways or roadway segments. access classification: See access category. access connection: See connection. access management: The systematic control of the location, spacing, design, and operation of driveways, median openings, inter- changes, and street connections to a roadway, as well as roadway design applications that affect access, such as median treatments and auxiliary lanes, and the appropriate separation of traffic signals. access management plan: A plan showing the location, and in some cases the design, of access for every parcel on a major road- way segment or within an interchange area that is often jointly developed and adopted by the state (if the road is a state high- way) and local agencies having jurisdiction over land develop- ment in the affected area. access operation: Use of an access for its intended purpose, in terms of access volume, type of access traffic, access safety, time of the access activity, and the effect of such access on the road- way system. access permit: A permit issued by a governmental agency for the construction, maintenance, and use of a driveway or public street connecting to a highway. access point: See connection. alternative access: The ability of any vehicle to enter a roadway indirectly through a roadway of lower functional classification. approach: The set of lanes making up one leg of an intersection. arterial: A major roadway intended primarily to serve through traf- fic, where access is carefully controlled. These are roadways of regional importance, intended to serve moderate to high volumes of traffic traveling relatively long distances and at higher speeds. auxiliary lane: A lane striped for use, but not for through traffic. average annual daily traffic or AADT: The total two-way yearly traffic volume on a section of roadway, divided by 365. This is often referred to as average daily traffic (ADT). bandwidth: The time in elapsed seconds between the passing of the first and last possible vehicle in a group of vehicles moving at the design speed through a progressive traffic signal system. It is a quantitative measurement of the through traffic capacity of a sig- nal progression system; the greater the percentage of bandwidth, the higher the roadway capacity. capacity: The maximum rate of flow at which vehicles reasonably can be expected to traverse a point on a lane or road during a specified period under prevailing traffic, roadway, and signal- ization conditions, usually expressed as vehicles per hour. Capacity is most often considered the maximum amount of traf- fic that can be accommodated by a roadway during the peak hours of demand. channelization: The separation or regulation of conflicting traffic movements into definite paths of travel by traffic islands or pave- ment markings to facilitate safe and orderly movement of both vehicles and pedestrians. collector: Roads intended to move traffic from local roads to secondary arterials. condemnation: The process by which property is acquired for high- way purposes through legal proceedings based on the power of eminent domain. conflict: A traffic event that causes evasive action by a driver to avoid collision with another vehicle, usually designated by a braking application or evasive lane change. conflict point: An area where intersecting traffic merges, diverges, or crosses. connection: Any driveway, street, turnout, or other means of providing for the movement of vehicles to or from the public roadway system. connection spacing: The distance between connections, measured from the closest edge of pavement of the first connection to the closest edge of pavement of the second connection along the edge of the traveled way. control of access: The condition in which the right of access of owners or occupants of land abutting a roadway is controlled by a public authority. controlled access roadway: A roadway to which abutting proper- ties have no legal right of access except in accordance with the requirements of the public authority having jurisdiction over that roadway. corner clearance: The distance from an intersection of a public or private road to the nearest access connection, measured from the closest edge of the pavement of the intersecting road to the closest edge of the pavement of the connection along the trav- eled way. corridor management: The coordinated application of multiple strategies to achieve specific land development and transporta- tion objectives along segments of a transportation corridor. corridor management planning: The process for identifying and addressing issues of strategic importance to the long-term func- tioning and character of a transportation corridor. Typical elements of the process include corridor designation, partnering agreements, visioning, corridor analysis, alternatives develop- ment and selection, and an implementation plan and agreements. corridor overlay zone: Special requirements added onto existing land development requirements along a designated portion of a public thoroughfare. corridor preservation: The coordinated application of various measures to obtain control or protection of the right-of-way for a planned transportation facility, as well as measures to preserve the capacity of existing roadways through access management. cross access: An easement or service drive providing vehicular access between two or more contiguous sites so that the driver does not need to reenter the public street system. crossover: See median opening. crossroad: The lower-functioning roadway that crosses the main higher-functioning roadway.
curb cut: An opening along the curb line where vehicles may enter or leave the roadway. deceleration lane: A speed-change lane, including tapered areas, that enables a turning vehicle to exit a through lane and slow to a safe speed to complete its turn. dedication: A conveyance of property by a private owner to the public. directional median opening: An opening in a restrictive median that provides for specific movements and physically restricts other movements. diverging: The dividing of a single stream of traffic into separate streams. diverted trip: A trip not new to a study area, but that uses a segment of the transportation system that previously had not been used to access a development site. divided roadway: A roadway on which traffic traveling in opposite directions is physically separated by a median. driveway: The physical connection for vehicular traffic between a roadway and abutting land. driveway flare: A triangular pavement surface at the entrance of a driveway that facilitates turning movements and is used to repli- cate turning radius in areas with curb and gutter construction. driveway return radius: A circular pavement transition at the entrance of a driveway that facilitates turning movements. easement: A right-of-way granted, but not dedicated, for specific and limited use of private land and within which the owner of the property shall not erect any permanent structures. egress: The act of leaving a place or exiting; the exit of vehicular traffic from abutting properties to a roadway. eminent domain: The authority to acquire or take, or to authorize the taking of, private property, with just compensation, for pub- lic use or public purpose. exception: Permission to depart from design standards in an ordi- nance due to unique circumstances of the site or project. expressway: A principal arterial roadway designed for relatively uninterrupted, high-volume mobility between areas, access to which is limited and may include a mixture of intersections (at grade) and interchanges (grade separated). freeway: A principal arterial roadway designed for relatively unin- terrupted, high-volume mobility between areas, access to which is limited to grade-separated interchanges only. Interstate high- ways are freeways. frontage road: An access road that generally parallels a major public roadway between the right-of-way of the major roadway and the front building setback line. The frontage road provides access to private properties while separating them from the principal roadway. functional area: That area beyond the physical intersection of two controlled access facilities that comprises decision and maneu- ver distance, plus any required vehicle storage length, and is protected through corner clearance standards and connection spacing standards. See also intersection. functional classification: A system used to group public roadways into classes according to their purpose in moving vehicles and providing access. grade separation: A crossing of two roadways, or a roadway and a railroad, or a roadway and a pedestrian walkway at different elevations. gradient or grade: The rate or percent change in slope, either ascending or descending from or along the highway. It is to be measured along the centerline of the roadway or access point. 73 impact analysis: A study to determine the potential direct or indi- rect effects of a proposed development on activities, utilities, cir- culation, surrounding land uses, community facilities, environ- ment, and other factors. impact fee: A fee imposed on a development to finance the cost of improvements or services. improvement: The original work on a road and subsequent repairs. Improvement consists of location, grading, and surface and subsurface drainage provisions, including curbs, gutters, catch basins, foundations, shoulders and slopes, wearing sur- face, bridges, culverts, retaining walls, intersections, private entrances, guard rails, shade trees, illumination, guideposts and signs, ornamentation, and monumenting. Improvement also may consist of alterations to driveways and local streets, acquisition of right-of-way, construction of service roads, and other actions designed to enhance the functional integrity of a roadway. ingress: Entry into a place; the entrance of vehicular traffic into abutting properties from a roadway. interchange: A grade-separated system of access to and from high- ways that includes directional ramps for access to and from crossroads. interchange management plan: A plan similar in nature to an access control plan but limited to the immediate influence area of an interchange for the protection of its functional integrity. interparcel circulation: The ability of vehicular traffic to circulate between adjacent parcels without reentering a public roadway. interrupted flow: A category of traffic flow that occurs on road- ways having traffic signals, stop or yield signs, or other fixed causes of periodic delay or interruption to the traffic stream. intersection: Any at-grade connection with a roadway, including two roads or a driveway and a road. intersection (roadway): The location where two roadways cross at grade. inverse condemnation: The taking or reduction in value of private property as a result of governmental activity, without any formal direct exercise of eminent domain. joint use connection: A single access point connecting two or more contiguous sites to a public roadway that serves more than one property or development, including those in different ownership or in which access rights are provided in legal descriptions. landlocked: A lot or parcel of land without access to a public road. level of service or LOS: A qualitative measure describing the opera- tional conditions within a stream of traffic. The measure uses factors including speed, travel time, ability to maneuver, traffic interrup- tions, safety, waiting time periods (delay), and driver comfort and convenience. Level of service is represented by one of the letters A through FâA for the freest flow and F for the least free flow. limited access roadway: A roadway especially designed for through traffic and where owners or occupants of abutting land (or other persons) have no right or easement of access. local road: A roadway with the primary function of providing access to adjacent properties and to roadways of a higher func- tional classification. lot: A designated parcel, tract, or area of land established by plat, subdivision, or as otherwise permitted by law, to be separately owned, used, developed, or built upon. major traffic generator: A land use that generates a high traffic volume to and from the site, usually defined in terms of vehicles per hour or vehicles per day. Volumes used to differentiate major versus minor vary widely.
74 median: That portion of a highway separating opposing traffic flows, not including center two-way left-turn lanes. Medians can be traversable or nontraversable. median, nontraversable, or restrictive median: A physical barrier in the roadway, such as a concrete barrier or landscaped island, that separates traffic traveling in opposite directions. median opening: An opening in a nontraversable median that pro- vides for crossing and turning traffic. median, traversable, or nonrestrictive median: A median that, by its design, does not physically discourage or prevent vehicles from entering upon or crossing over it, including painted medians. merge: The process by which two separate traffic streams moving in the same direction combine or unite to form a single stream. minor traffic generator: A land use that generates a low traffic volume to and from the site, usually defined in terms of vehicles per hour or vehicles per day. Volumes used to differentiate minor versus major vary widely. non-use: The absence or lack of any significant and ongoing eco- nomic activity on a property or use of the access by the owner or authorized persons, in terms of the zoning and past use of the property or access. Non-use includes the occasional and incon- sequential presence upon such property or access. outparcel: A lot, adjacent to a roadway, which interrupts the frontage of another lot. parkway: A type of limited access roadway that typically includes a landscaped median and landscaping or open space on either side. peak hour: The largest number of vehicles passing over a desig- nated section of a street during the busiest 60-minute period dur- ing a 24-hour period. phase: That portion of a traffic signal cycle allocated to a specific traffic movement or combination of movements. plat: An exact and detailed map of the subdivision of land. protected turns: Left or right turns allowed by a signal at an inter- section, where the signal simultaneously prohibits opposing or conflicting traffic movement. rational nexus: A clear, direct, and substantial relationship between a particular development and the public improvement needs generated by the development. reverse frontage: Frontage on an access road constructed at the rear of lots fronting on a major roadway. right-of-way or ROW: A strip of land occupied or intended to be occupied by a road, sidewalk, crosswalk, railroad, electric trans- mission line, oil or gas pipeline, water line, sanitary storm sewer, and other similar uses. Generally meaning the right of one to pass over the property of another. right-of-way line: The line that forms the boundaries of a right-of- way. service road: A public or private road, auxiliary to an arterial road- way, that provides access to parcels surrounding an arterial road- way and that typically serves nonresidential development. shared access: A single connection serving two or more adjoining lots or parcels. shoulder: The portion of the roadway that lies between the edge of the traveled way and the curb line, excluding auxiliary lanes. sight distance: The distance visible to the driver of a passenger vehicle measured along the normal travel path of a roadway from a designated location and to a specified height above the roadway when the view is unobstructed by traffic. sight triangle: An area of unobstructed sight distance along both approaches of an access connection. signal progression: The progressive movement of traffic, at a planned rate of speed without stopping, through adjacent signal- ized locations within a traffic control system. signal spacing: The distance between traffic signals along a road- way. speed-change lane: A separate lane for the purpose of enabling a vehicle entering or leaving a roadway to increase or decrease its speed to a rate at which it can more safely merge or diverge with through traffic. Acceleration and deceleration lanes are speed- change lanes. See also auxiliary lane. stopping sight distance: The distance required by a driver of a vehicle traveling at a given speed to bring the vehicle to a stop after an object on the roadway becomes visible. It includes the distance traveled during driver perception and reaction times and the vehicle braking distance. storage length: Additional lane footage added to a deceleration lane to store the maximum number of vehicles likely to accumu- late during a peak period so as not to interfere with the through travel lanes. strategic arterial: A designation for arterial roadways having strategic importance to the statewide transportation network that is used for planning purposes. stub-out or stub-street: A portion of a roadway or cross-access drive used as an extension to an abutting property that may be developed or redeveloped in the future. taper: The widening of pavement to allow the redirection and transition of vehicles around or into an auxiliary lane. There are two different types of tapers: (1) redirect tapers necessary for the redirection of vehicles along the traveled way, and (2) tran- sition tapers for auxiliary lanes that allow the turning vehicle to transition from or to the traveled way, to or from an auxiliary lane. temporary access or conditional access: Access that is permitted for use until alternative access becomes available. throat length: The distance parallel to the centerline of a driveway to the first on-site location at which a driver can make a right turn or a left turn. On roadways with curb and gutter, the throat length shall be measured from the face of the curb. On roadways with- out a curb and gutter, the throat length shall be measured from the edge of the shoulder. throat width: The distance edge to edge of a driveway measured at the right-of-way line. through movement: The predominant direction of traffic flow through an intersection; although the predominant flow of traffic occasionally is in a right- or left-turning direction, it is straight on most major roads. time-space diagram: A chart on which the distance between sig- nals and signal timing is plotted against time. The chart indicates signal progression, efficiency, bandwidth, and speed of traffic. Efficiency is the width of the through band expressed as a frac- tion of the entire signal cycle. A 50 percent efficiency means that 30 seconds of a 60-second signal cycle is devoted to the move- ment of through traffic. traffic characteristics: Parameters describing the distribution of vehicles in a traffic stream, such as planning analysis hour factor, direction distribution factor, peak hour factor, adjusted saturation flow rate, and percent turns from exclusive turn lanes. traffic control device: Any sign, signal, marking, or device placed or erected for the purpose of regulating, warning, or guiding vehicular traffic and/or pedestrians.
traffic count: A tabulation of the number of vehicles or pedestrians passing a certain point during a specified period of time. traffic impact study: A report analyzing anticipated roadway conditions with and without an applicantâs development. The report includes an analysis of mitigation measures and a calcula- tion of fair-share financial contributions. traveled way: The portion of the roadway provided for the move- ment of vehicles, exclusive of shoulders and auxiliary lanes. trip: A single or one-directional vehicle movement with either the origin or the destination inside a study area. A vehicle leaving the highway and entering a property is one trip. When the vehi- cle leaves the property, it is a second trip. trip distribution: The measure of the number of vehicles or pas- senger movements that are or will be made between geographic areas. two-way left-turn lane, continuous, or TWLTL: A continuous lane located between opposing traffic flows that provides a refuge area for vehicles to complete a left turn from a roadway. undivided roadway: A roadway having no directional separator, nat- ural or structural, to separate traffic moving in opposite directions. 75 uninterrupted flow: The category of traffic flow that occurs on roadways having no fixed cause of delay; examples of such roadways include freeways and non-signalized sections of rural highways. unprotected turns: At an intersection, left or right turns through an opposing flow of vehicles or pedestrians not under the direction of a signal phase for protected turns. vehicles per hour or VPH: The number of vehicles per hour, usually referring to vehicles in a peak hour. waiver: Permission to depart from a regulatory standard where required conditions are satisfied. warrant: The criteria by which the need for a safety treatment or roadway improvement can be determined. weaving: The crossing of two or more traffic streams traveling in the same general direction along a significant length of highway without the aid of traffic-control devices. Weaving areas are formed where a merge area is closely followed by a divergent area or where an entrance ramp is closely followed by an exit ramp and the two ramps are joined by an auxiliary lane.
