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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2016. Guidelines for Implementing Managed Lanes. Washington, DC: The National Academies Press. doi: 10.17226/23660.
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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.

128 Term Definition Source Acceleration Increase in velocity per unit time; in transit, usually measured in feet per second squared (meters per second squared) or, in the United States, sometimes in miles per hour per second. Kittelson & Associates et al. (119) Access The means of entering and exiting a designated roadway facility such as a managed lane or general-purpose lanes. Research Team Access, continuous See continuous access. Accessibility 1. A measure of the ability or ease of all people to travel among various origins and destinations. 2. In transportation modeling and planning, the sum of the travel times from one zone to all other zones in a region, weighted by the relative attractiveness of the destination zones involved. 3. In traffic assignment, a measure of the relative access of an area or zone to population, employment opportunities, community services, and utilities. Kittelson & Associates et al. (119) Accessibility, persons with disabilities (full accessibility) The extent to which facilities are free of barriers and usable by persons with disabilities, including wheelchair users. Kittelson & Associates et al. (119) Accessibility, station A measure of the ability of all people within a defined area to get to a specific transit station. Kittelson & Associates et al. (119) Accessibility, transit 1. A measure of the availability to all people of travel to and from various origins and destinations by transit. 2. A measure of the ability of all people to get to and from the nearest transit stop or station and their actual origin or destination. 3. In common usage, often used to mean the ability of persons with disabilities to use transit. Kittelson & Associates et al. (119) Advanced traffic management system Remotely operated traffic management system for monitoring and man- aging operations of a freeway system including HOV lanes and arterial streets. Major elements of the system include surveillance, communications, and controls. Kuhn et al. (4) Alignment In transportation, the horizontal and vertical layout of a roadway, rail- road, transit route, or other facility as it would appear in plan and profile. Usually described on the plans by the use of technical data, such as grades, coordinates, bearings, and horizontal and vertical curves. Kittelson & Associates et al. (119) Glossary

129 Alternative fuels Alternatives to conventional diesel fuel for urban transit buses, intended to reduce pollution. Includes methanol, propane, CNG (compressed natural gas), LNG (liquefied natural gas), hydrogen (for fuel cells), and biomass- derived fuels. All carry premium costs that trend in larger or more cost- conscious operators toward clean diesel solutions. Kittelson & Associates et al. (119) Americans with Disabilities Act of 1990 (ADA) Federal civil rights law that ensures people with disabilities equal oppor- tunity to fully participate in society, the ability to live independently, and the ability to be economically sufficient. Kittelson & Associates et al. (119) Arterial roadway A signalized street that primarily serves through traffic and secondarily provides access to abutting properties; signal spacing is typically 2 mi (3 km) or less. Kittelson & Associates et al. (119) Articulated bus or articulated trolleybus An extra-long, high-capacity bus or trolleybus that has the rear body section or sections flexibly but permanently connected to the forward section. The arrangement allows the vehicle to bend in curves and yet have no interior barrier to movement between the two parts. Typically, an articulated bus is 54–60 ft (16–18 m) long with a passenger seating capacity of 60 to 80 and a total capacity of 100 to 140. Kittelson & Associates et al. (119) Automated vehicles (AVs) Vehicles in which some aspects of a safety-critical control function (e.g., steering, throttle, or braking) occur without direct driver input. NHTSA (17) Automatic vehicle location The use of advanced technologies such as global positioning systems to monitor the location and movement of vehicles. Kuhn et al. (4) Auxiliary lane A short-distance travel lane typically striped between closely spaced ramps that facilitate weaving, merging, and diverging movements. Research Team Availability payment A form of compensation to private-sector concessionaires for design, construction, operations, and/or maintenance of managed lanes that are independent from project-related revenue generation. AASHTO (107) Average daily traffic The average 24-hour volume, being the total volume during a stated period divided by the number of days in that period. Would normally be periodic daily traffic volumes over several days, not adjusted for days of the week or seasons of the year. FHWA (1) Average trip length Passenger miles divided by unlinked passenger trips. Can be computed for pedestrian trips and vehicle trips, based on special surveys. Kittelson & Associates et al. (119) Average vehicle occupancy The number of people divided by the number of vehicles (including buses) traveling past a specific point over a given time period. Kuhn et al. (4) Barrier A physical separation employed between concurrent or opposing flows of traffic, often made of concrete and permanently affixed to the roadway. Research Team Barrier free Containing no obstacles that would prevent use by persons with disabilities or any other person. Research Team Barrier-separated lane A preferential lane or other special-purpose lane that is separated from the adjacent general-purpose lane(s) by a physical barrier. FHWA (1) Term Definition Source

130 Base period (off-peak period) In transit, the time of day during which vehicle requirements and schedules are not influenced by peak-period passenger volume demands (e.g., between morning and afternoon peak periods). At this time, transit riding is fairly constant and usually moderate in volume when compared with peak-period travel. See also off-peak. Kittelson & Associates et al. (119) Beacon Short-range roadside transceiver for communicating between vehicles and the traffic management infrastructure. Common transmission tech- nologies include microwave and infrared. Kittelson & Associates et al. (119) Beacon (signal) A highway traffic signal with one or more signal sections that operate in a flashing mode. FHWA (1) Benefit–cost ratio Estimate of the anticipated dollars of discounted benefits achievable to a given outlay of discounted costs. Kuhn et al. (4) Bidirectional HOV facility Preferential facility in which both directions of traffic flow are provided for. Kuhn et al. (4) Boarding island 1. A pedestrian refuge within the right-of-way and traffic lanes of a high- way or street. It is provided at designated transit stops for the protection of passengers from traffic while they wait for and board or alight from transit vehicles; also known as a pedestrian or loading island. 2. A protected spot for the loading and unloading of passengers. It may be located within a rail transit or bus station. 3. On streetcar and light rail systems, a passenger loading platform in the middle of the street, level with the street or more usually raised to curb height, often protected with a bollard facing traffic. Kittelson & Associates et al. (119) Bollard A short vertical post to prevent the unauthorized or unintended entry of vehicles into an area. Research Team Buffer The pavement space between the managed lane and general-purpose lanes designated by pavement markings, typically no more than 4 ft in width. Research Team Buffer-separated lane A preferential lane or other special-purpose lane that is separated from the adjacent general-purpose lane(s) by a pattern of standard longitudi- nal pavement markings that are wider than a normal or wide lane line marking. The buffer area might include rumble strips, textured pavement, or channelizing devices such as tubular markers or traversable curbs but does not include a physical barrier. FHWA (1) Bus A self-propelled, rubber-tired road vehicle designed to carry a substan- tial number of passengers (at least 16, various legal definitions may differ slightly as to minimum capacity), commonly operated on streets and high- ways. A bus has enough headroom to allow passengers to stand upright after entering. Propulsion may be by internal combustion engine, electric motors, or hybrid. Smaller-capacity road transit vehicles, often without full headroom, are termed vans. Kittelson & Associates et al. (119) Bus, articulated See articulated bus or articulated trolleybus. Term Definition Source

131 Bus, double-decker A high-capacity bus that has two levels of seating, one over the other, connected by one or two stairways. Total bus height is usually 13–14.5 ft (4.0–4.4 m), and typical passenger seating capacity ranges from 60 to 80 people. Kittelson & Associates et al. (119) Bus bay 1. A branch from or widening of a road that permits buses to stop, with- out obstructing traffic, while laying over or while passengers board and alight; also known as a blister, duckout, turnout, pullout, pull-off, or lay-by. As reentry of the bus into the traffic stream can be difficult, many transit agencies discourage bus bay construction. 2. A specially designed or des- ignated location at a transit stop, station, terminal, or transfer center at which a bus stops to allow passengers to board and alight; also known as a bus dock or bus berth. 3. A lane for parking or storing buses in a garage facility, often for maintenance purposes. Kittelson & Associates et al. (119) Bus bay, angle A bus bay design similar to an angled parking space that requires buses to back up to exit; allows more buses to stop in a given linear space. Typically used when buses will occupy the berth for a long period of time (for example, at an intercity bus terminal). Kittelson & Associates et al. (119) Bus bay, drive-through (pull-through) A bus bay design providing several adjacent loading islands, between which buses drive through, stop, and then exit. Allows bus stops to be located in a compact area. Sometimes used at intermodal transfer centers because all buses can wait with their front destination signs facing the direction passengers will arrive from (e.g., from a rail station exit). Kittelson & Associates et al. (119) Bus bay, linear A bus bay design where buses stop directly behind each other; requires the bus in front to leave its bus bay before the bus behind it can exit. Often used when buses will use the bus bay only for a short time (e.g., at an on-street bus stop). Also called on-line bus stop. Kittelson & Associates et al. (119) Bus bay, sawtooth A bus bay design where the curb is indented in a sawtooth pattern, allowing buses to enter and exit bus bays independently of other buses. Often used at transit centers. Kittelson & Associates et al. (119) Bus berth See bus bay. Bus bulb An extension of the sidewalk into the roadway for passenger loading without the bus pulling into the curb. Gives priority to buses and eases reentry into traffic. Often landscaped and fitted with bus shelter and other passenger amenities. Also called bus bulge, curb bulge, and curb extension. Kittelson & Associates et al. (119) Bus lane A lane dedicated for the exclusive or primary use of buses, typically located alongside other general-purpose lanes on a controlled-access roadway or street. Kittelson & Associates et al. (119) Bus priority system A system of traffic controls in which buses are given special treatment over general vehicular traffic (e.g., bus priority lanes, preemption of traffic signals, or adjustment of green times for buses). Kittelson & Associates et al. (119) Bus priority system, metered freeway A means of giving buses preferential access to enter a freeway by restraining the entrance of other vehicles through the use of ramp metering; see also freeway, metered. Kittelson & Associates et al. (119) Term Definition Source

132 Bus rapid transit (BRT) A bus operation that is generally characterized by operation on a separate right-of-way that permits high speeds. Kuhn et al. (4) Bus shelter See transit shelter. Bus stop See stop, transit. Bus transit See bus. Busway A roadway designed and dedicated for exclusive use by buses. May be constructed at, above, or below grade and may be located in separate rights-of-way or within highway corridors. Variations include grade- separated, at-grade, and median busways. Sometimes called a transitway. Adapted from Kittelson & Associates et al. (119) Bypass lane See queue jumper. Bypass, queue See queue jumper. Capacity, design For highways, the maximum number of vehicles that can pass over a given section of a lane or roadway in one or both directions during a given time period under prevailing environmental (e.g., weather and light), roadway, and traffic conditions. Kittelson & Associates et al. (119) Capacity, maximum The maximum number of persons or transit vehicles that can pass a given point in a given period of time, without regard to reliability or passenger comfort. This is a theoretical value that should not be used for planning in most cases. Kittelson & Associates et al. (119) Capacity, person The maximum number of persons that can be carried past a given location during a given time period under specified operating conditions without unreasonable delay, hazard, or restriction. Usually measured in terms of persons per hour. Kittelson & Associates et al. (119) Carpool An arrangement in which two or more people share the use, cost, or both of traveling in privately owned automobiles between fixed points on a regular basis; see also vanpool. Kittelson & Associates et al. (119) Carpool, casual An informal carpool where commuters gather at a location to be picked up at random by motorists who do not have sufficient passengers. Kittelson & Associates et al. (119) Carpool lane See lane, carpool and lane, exclusive carpool. Carrier A person or company in the business of transporting passengers or goods. Kittelson & Associates et al. (119) Carrier, common In urban transportation, a company or agency certified by a regulatory body to carry all passengers who fulfill the contract (e.g., pay the required fare). The service is open to the public. Kittelson & Associates et al. (119) Center platform A passenger platform located between two tracks or guideways so that it can serve them both. Kittelson & Associates et al. (119) Central business district Commonly referred to as downtown. Kuhn et al. (4) Change of mode Transfer from one type of transportation vehicle to another. Kuhn et al. (4) Term Definition Source

133 Channelizer (also called pylon or delineator) 1. Plastic tube permanently employed to provide a visual barrier between concurrent traffic streams, typically located in a painted buffer area between the managed lane and general-purpose lanes. 2. Portable plastic tube inserted into the pavement into predrilled holes to delineate a contraflow lane during its operating period. Kuhn et al. (4) Commute Regular travel between home and a fixed location (e.g., work, school). Often applied only to travel in the direction of the main flow of traffic, to distinguish from reverse commute. Kittelson & Associates et al. (119) Commute, reverse A commute in the direction opposite to the main flow of traffic, for example, from the central city to a suburb during the morning peak. Increasingly common with growth in suburban employment. Valuable to operator because it provides additional passengers and revenue at little or no marginal cost. Kittelson & Associates et al. (119) Commute trips Trips that are taken on a daily or regular basis to work. Kuhn et al. (4) Commuter A person who travels regularly between home and a fixed location (e.g., work, school). Kittelson & Associates et al. (119) Concept of operations A comprehensive description of system characteristics of a managed lanes facility, including organizational objectives, integrated systems descrip- tion, and high-level description of intended operations that inform the specification of functions and design. Research Team Concurrent-flow lane A preferential lane that is operated in the same direction as the adjacent general-purpose lanes, separated from the adjacent general-purpose freeway lanes by a standard lane stripe, painted buffer, or barrier. FHWA (1) Confidence level A statement of assurance of the accuracy of a statistical statement. For instance, if it is asserted that a population parameter is indeed within the computed confidence interval at confidence level a, then the risk of error is 1-a. For example, a 95-percent confidence level has a risk of 5 percent. Kittelson & Associates et al. (119) Confidence limit A boundary of the confidence interval, usually referred to as lower and upper confidence limits. Kittelson & Associates et al. (119) Congestion pricing The policy of charging drivers a fee that varies with the level of traffic on a congested roadway. Designed to allocate roadway space, a scarce resource, in a more economically feasible manner. Also called congestion-relief tolling. Kuhn et al. (4) Connected vehicle A vehicle containing an onboard unit or after-market safety device. May alternatively include a vehicle awareness device, which transmits the basic safety message but does not receive broadcasts from other devices and cannot directly support vehicle-based applications. FHWA (18) Connectivity The ability of a public transportation network to provide service to the maximum number of origin-and-destination trip pairs through the opti- mal integration of routes, schedules, fare structures, information systems, and modal transfer facilities. Kittelson & Associates et al. (119) Term Definition Source

134 Continuous access (also called open access) A managed lane that allows access anywhere along its length, typically separated from the general-purpose lanes of traffic by a painted stripe. Kuhn et al. (4) Contraflow Movement in a direction opposite to the normal flow of traffic. Usually refers to flow opposite to the heavier flow of traffic. See also commute, reverse. Kittelson & Associates et al. (119) Contraflow lane A managed lane operating in the opposite direction of the normal flow of traffic and designated for peak-direction travel; separated by pylons or moveable barrier. Kuhn et al. (4) Cost Resources used to produce a product or service. Research Team Deadheading Segment of a trip made by a transit vehicle not in revenue service. Kuhn et al. (4) Delay The increased travel time experienced due to circumstances that impede a desirable movement of traffic. Kuhn et al. (4) Demand 1. The quantity (of transportation) desired. 2. In an economic sense, a schedule of the quantities (of travel) consumed at various levels of price or levels of service offered (by the transportation system). Kittelson & Associates et al. (119) Demand, effective The number of people or vehicles prepared to travel in a given situation, at a given price. Kittelson & Associates et al. (119) Demand–response connector Provides demand-responsive service within a defined zone that has one or more scheduled transfer points to fixed-route transit. The transfer points may be a bus stop for peak-period express or other bus service, or a rail service. Kittelson & Associates et al. (119) Demand-side policies Aimed at reducing congestion by reducing the demand for travel, either overall or by targeted modes. Kuhn et al. (4) Design capacity See capacity, design. Design hourly volume The amount of traffic a transportation facility is designed to carry in 1 hour. Kittelson & Associates et al. (119) Design vehicle A vehicle with representative weight, dimensions, and operating charac- teristics used to establish highway design controls for accommodating designated vehicle classes. AASHTO (27) Destination 1. The point at which a trip terminates. 2. In planning, the zone in which a trip ends. Kittelson & Associates et al. (119) Differential pricing (variable pricing) Time-of-day pricing and tolls that vary by other factors like facility loca- tion, season, day of week, or air quality impact. Kuhn et al. (4) Direct ramp Grade-separated managed lane ramp dedicated to the use of eligible vehicles. Research Team Directional split The distribution of traffic flows on a two-way facility. Kuhn et al. (4) Dynamic pricing Tolls that vary in response to changing congestion and demand levels, as opposed to variable pricing that follows a fixed schedule. Research Team Term Definition Source

135 Dynamic shoulder lanes A strategy that enables the use of the shoulder as a travel lane—known as hard shoulder running or temporary shoulder use—based on congestion levels during peak periods and in response to incidents or other conditions as warranted during non-peak periods. In contrast to a static time-of-day schedule for using a shoulder lane, an active traffic and demand manage- ment approach continuously monitors conditions and uses real-time and anticipated congestion levels to determine the need for using a shoulder lane as a regular or special-purpose travel lane (e.g., transit only). FHWA (120) Effective operating speed See speed, overall trip. Electronic toll collection (ETC) A system for automated collection of tolls from moving or stopped vehicles through wireless technologies such as radio-frequency communication or optical scanning. ETC systems are classified as one of the following: (a) systems that require users to have registered toll accounts, with the use of equipment inside or outside vehicles, such as a transponder or barcode decal, that communicates with or is detected by roadside or overhead receiving equipment, or with the use of license plate optical scanning, to automatically deduct the toll from the registered user account; or (b) systems that do not require users to have registered toll accounts because vehicle license plates are optically scanned and invoices for the toll amount are sent through postal mail to the address of the vehicle owner. FHWA (1) Electronic toll collection account- only lane Non-attended toll lane that is restricted to use by only vehicles with a registered toll payment account. FHWA (1) Enforcement Function of maintaining the rules and regulations for a managed lane to maintain operational integrity. Research Team Enforcement area Designated space on which enforcement can be performed. Kuhn et al. (4) Envelope The width constituting a managed lane operation including the directional travel lane(s) and shoulder/buffer on each side. Research Team Environmental assessment Study to determine the potential impacts on the environment from a project. Kuhn et al. (4) Environmental impact statement Comprehensive study of all the potential impacts of a project funded with federal dollars. Kuhn et al. (4) Exclusive transit facilities Transportation system infrastructure elements that are set aside for the use of bus transit vehicles only. Examples include some freeway ramps, queue jumpers, bus lanes, off-street bus loading or unloading areas, and guideways that are separated and fully controlled for bus transit. Research Team Exclusive transit lane See lane, exclusive transit. Exclusive transitway See transitway. Express bus service Bus service with a limited number of stops, usually at a high speed. Kuhn et al. (4) Term Definition Source

136 Express lanes Lanes that restrict access (e.g., I-94 Dan Ryan in Chicago) or, according to the MUTCD definition, a managed lane that employs electronic tolling in a freeway right-of-way with or without access restrictions. Research Team Express service See service, express. Express toll lane or roadway Dedicated lanes that are typically access restricted and employ electronic toll collection to manage demand. Research Team Expressway A divided arterial highway for through traffic. Has full or partial control of access and generally has grade separations at major intersections. Kittelson & Associates et al. (119) Facilities, exclusive transit See exclusive transit facilities. Factor, peak-hour See peak-hour factor. Fees for entering Tolls charged to vehicles entering a particular facility or an area but that do not depend on the distance traveled on the facility or in the area. Kuhn et al. (4) Fixed guideway Transportation system composed of vehicles that can operate only on their own guideways. Kuhn et al. (4) Flyover ramp A moderately high-speed, grade-separated ramp that connects a managed lane to another freeway, street, or transit-supporting facility. Research Team Forecasting In planning, the process of determining the future conditions, magni- tudes, and patterns within the urban area, such as future population, demographic characteristics, and travel demand. Kittelson & Associates et al. (119) Freeway A high-speed divided highway with full control of access. FHWA (1) Freeway, metered A freeway to which access is controlled by entrance ramp signals that use fixed-time signal settings or are regulated by a computerized surveillance system that monitors demand. Used to prevent or forestall the onset of freeway congestion. Kittelson & Associates et al. (119) Freight or truck lane A facility or lane restricted to authorized truck types. Kuhn et al. (4) General-purpose lanes Lanes on a freeway or expressway that are open to all motor vehicles. Kuhn et al. (4) Geographic informa- tion system A computerized database management system in which geographic data- bases are related to one another via a common set of location coordinates. Can provide a spatial, interactive visual representation of transit operations and allow users to make queries and selections of database records based on geographic proximity and attributes such as bus stop activity levels and demographic data. Kittelson & Associates et al. (119) Global positioning system A system that determines the real-time position of vehicles using communi- cations with a satellite. Refers more specifically to a government-owned sys- tem of earth-orbiting satellites that transmit data to ground-based receivers and provide extremely accurate latitude/longitude ground positions. Kittelson & Associates et al. (119) Grade or gradient Rise in elevation within a specified distance. As an example, a 1-percent grade is a 1-ft rise in elevation in 100 ft of horizontal distance, in Britain expressed as 1/100 or 1 in 100, and in Europe 10°/1000. Kittelson & Associates et al. (119) Term Definition Source

137 Grade separation A vertical separation of intersecting facilities (road, rail, etc.) by the provi- sion of bridge structures. Kittelson & Associates et al. (119) Guide sign A sign that shows route designations, destinations, directions, distances, services, points of interest, or other geographical, recreational, or cultural information. FHWA (1) Headway The time interval between the passing of the front ends of successive tran- sit units (vehicles or trains) moving along the same lane or track (or other guideway) in the same direction, usually expressed in minutes; see also service frequency. Kittelson & Associates et al. (119) Headway, base The scheduled headway between transit unit (vehicle or train) trips, between peak periods. Kittelson & Associates et al. (119) Headway, clock The scheduled headway between transit unit (vehicle or train) trips, based on even times (i.e., 60, 30, 20, 15, 10, and 7½ minutes). Kittelson & Associates et al. (119) Headway management A technique for managing the operation of transit units (vehicles or trains) that focuses on maintaining a certain spacing between units on the same line instead of on adhering to a timetable. For example, if units become bunched, corrective measures might include delaying the units at the rear of the bunch to provide regular headways and hence load distri- bution, even at the expense of reducing timetable adherence. Kittelson & Associates et al. (119) High-occupancy toll (HOT) lanes HOV facilities that allow lower-occupancy vehicles, such as solo drivers, to use the facilities in return for toll payments, which could vary by time of day or level of congestion. May also charge lower-occupancy HOVs. Kuhn et al. (4) High-occupancy vehicle (HOV) A motor vehicle carrying at least two or more persons, including carpools, vanpools, and buses. FHWA (1) High-occupancy- vehicle lane See lane, high-occupancy-vehicle. High-occupancy- vehicle system Development and operation of a coordinated approach of physical improve- ments such as HOV lanes, park-and-ride lots, and supporting services and policies. Kuhn et al. (4) Highway Capacity Manual A standard reference used to calculate the capacity and quality of service of roadway facilities. Kittelson & Associates et al. (119) HOV lane management National ITS architecture market package that manages HOV lanes by coordinating freeway ramp meters and connector signals with HOV lane usage signals. Preferential treatment is given to HOV lanes using special bypasses and reserved lanes that may vary by time of day. Kittelson & Associates et al. (119) HOV/HOT freeway- to-freeway connectors Special freeway-to-freeway ramps restricted to HOV/HOT lane-eligible vehicles. Kuhn et al. (4) Incentive programs Policies and techniques aimed at a specific behavior. Kuhn et al. (4) Ingress The provision of access into a roadway. Kuhn et al. (4) Inherently low- emission vehicles Alternatively fueled clean air vehicles. Related terms include zero-emission vehicles, ultra-low-emission vehicles, and super-ultra-low-emission vehicles powered by alternative fuels. Kuhn et al. (4) Term Definition Source

138 Integrated corridor management The operational coordination of multiple transportation networks and cross-network connections comprising a corridor and the institutional coordination of those agencies and entities responsible for corridor mobility. Gonzalez et al. (121, p. 5) Intelligent Transpor- tation Society of America A non-profit, public/private scientific and educational corporation that works to advance a national program for safer, more economical, more energy efficient, and environmentally sound highway travel in the United States. Federal advisory committee used by U.S. DOT. Kittelson & Associates et al. (119) Intelligent transporta- tion system (ITS) The application of advanced technologies to enhance the operation and management of a transportation system. Kuhn et al. (4) Interchange 1. Facility for passenger transfers or connection between routes or modes. 2. The system of interconnecting ramps between two or more intersecting travel ways (highways, transit guideways, etc.) that are grade separated. Kittelson & Associates et al. (119) Intermediate access The provision for access along and between the managed lane and general- purpose lanes, other than at the termini. Research Team Intermodal Facility connections between transportation modes. Kuhn et al. (4) Interoperability Ability to toll and process toll transactions and accounts from multiple operators and projects, either on a regional, statewide, or national level. Research Team Intersection The point at which two or more roadways meet or cross. Kittelson & Associates et al. (119) Island, loading or pedestrian See loading island. Island platform See center platform. Jerk Time rate of change of acceleration or deceleration of a vehicle, measured in ft/s3 (m/s3). Research Team Jitney Privately owned vehicle operated on a fixed or semi-fixed schedule for a fare. Kuhn et al. (4) K Factor In vehicle operations, the ratio of the minimum operating separation between two vehicles to the maximum emergency stopping distance. Normally greater than 1 to provide a margin of safety. Kittelson & Associates et al. (119) Kiss-and-ride Function whereby transit riders are dropped off and picked up near a transit station. Kuhn et al. (4) Lane, bus (bus priority lane, preferential bus lane, priority bus lane) A highway or street lane reserved primarily for buses, either all day or during specified periods. May be used by other traffic under certain cir- cumstances, such as making a right or left turn, or by taxis, motorcycles, or carpools that meet specific requirements described in the traffic laws of the specific jurisdiction. Kittelson & Associates et al. (119) Lane, bypass See queue jumper. Term Definition Source

139 Lane, carpool A highway or street lane intended primarily for carpools, vanpools, and other high-occupancy vehicles, including buses, either all day or during specified periods. May be used by other traffic under certain circumstances, such as while making a right turn. Kittelson & Associates et al. (119) Lane, contraflow A highway or street lane on which vehicles operate in a direction opposite to what would be the normal flow of traffic in that lane. Operate only during certain hours of the day, borrowing an off-peak lane for peak- direction travel. Frequently, the use of a contraflow lane is restricted to public transit and (possibly) other HOVs. Research Team Lane, diamond A concurrent-flow HOV lane physically marked by diamonds painted on the pavement and often indicated by diamond-shaped signs as well. Often used synonymously with high-occupancy-vehicle lane. Research Team Lane, exclusive carpool A highway or street lane reserved for carpools and vanpools. Kittelson & Associates et al. (119) Lane, exclusive transit (reserved transit lane) A highway or street lane reserved for buses, light rail vehicles, or both. Kittelson & Associates et al. (119) Lane, high-occupancy- vehicle (HOV lane) A highway or street lane reserved for the use of high-occupancy vehicles; see lane, carpool. Kittelson & Associates et al. (119) Lane, priority A highway or street lane reserved (generally during specified hours) for one or more specified categories of vehicles, for example, buses, carpools, vanpools. Kittelson & Associates et al. (119) Lane, ramp meter bypass A form of preferential treatment in which a bypass lane on metered freeway on-ramps is provided for the exclusive use of high-occupancy vehicles. Kittelson & Associates et al. (119) Lane, reserved transit See lane, exclusive transit. Lane, reversible A highway or street lane on which the direction of traffic flow can be changed to match the peak direction to use maximum roadway capacity during peak-period demands. Typically operate inbound in the morning and outbound in the afternoon, and are barrier separated. Research Team Lane-use control signal A signal face displaying indications to permit, conditionally permit, or prohibit the use of the lane of a roadway or to indicate the impending prohibition of such use. Typically, the display is a green arrow, yellow arrow, and red X. Research Team Left shoulder Pavement located on the left side of the managed lane travelway or general- purpose mainlanes used for enforcement and emergency stopping. Research Team Level of service (LOS) 1. A designated range of values for a particular service measure (e.g., “A” through “F” or “1” through “8”), based on users’ perceptions (see quality of service) of the aspect of transportation performance being measured. 2. The amount of transit service provided. Kittelson & Associates et al. (119) Light rail transit Mode of transit that operates on steel rails and is powered by overhead electrical wires. Kuhn et al. (4) Term Definition Source

140 Limited access Access management used to restrict entry to a facility based on facility congestion levels or operational condition, such as the presence of a crash or maintenance activities. Typically, access is not restricted by type of user. Kuhn et al. (4) Line haul Portion of a commute trip that is nonstop between two points. Kuhn et al. (4) Loading island 1. A pedestrian refuge, within the right-of-way and traffic lanes of a high- way or street, provided at designated transit stops for the protection of passengers from traffic while they wait for and board or alight from transit vehicles; also known as a pedestrian or boarding island. 2. A protected location for the loading and unloading of passengers. It may be located within a rail transit or bus station. Kittelson & Associates et al. (119) Local bus service Bus routes and service characterized by frequent stops and slow operating speeds. Kuhn et al. (4) Main lane General-purpose lane on a freeway that is open to all motor vehicles. Kuhn et al. (4) Main-lane metering Regulation of the flow of vehicles on general-purpose lanes or on freeway- to-freeway connections through the use of traffic signals that allow vehicles to proceed at a predetermined rate. Kuhn et al. (4) Major investment study Detailed study and assessment of the various options available for the purpose of selecting one for implementation. Kuhn et al. (4) Managed lane A highway lane or set of lanes, or a highway facility, for which operational strategies such as managing access, restricting eligibility, or employing variable pricing are implemented and managed during peak periods and often in real time in response to changing conditions. Are typically buffer- or barrier-separated concurrent-flow lanes parallel to the general-purpose lanes of a freeway. Research Team Manual on Uniform Traffic Control Devices (MUTCD) Defines the standards used by road managers nationwide to install and maintain traffic control devices on all public streets, highways, bikeways, and private roads open to public traffic. The MUTCD is published by FHWA under 23 CFR Part 655, Subpart f. FHWA (1) Median (median strip) The portion of a divided highway that separates the opposing flows of traffic. Research Team Metered freeway See freeway, metered. Metered freeway bus priority system See bus priority system, metered freeway. Metering, ramp See ramp metering. Mileage-based fee The fee charged for using a vehicle based on the vehicle miles traveled in a jurisdiction. Kuhn et al. (4) Mobility The ability to satisfy the demand to move a person or good. Kittelson & Associates et al. (119) Mode Means of travel (e.g., automobile, bus, carpool, vanpool). Research Team Mode shift The change from one means of travel to another. Kuhn et al. (4) Term Definition Source

141 Model 1. A mathematical or conceptual presentation of relationships and actions within a system. Used for analysis of the system or its evaluation under various conditions; examples include land use, economic, socioeconomic, and transportation. 2. A mathematical description of a real-life situation that uses data on past and present conditions to make a projection about the future. Kittelson & Associates et al. (119) Motor vehicle fuel tax Pricing of gasoline and other fuels. Kuhn et al. (4) Moveable barrier A type of concrete barrier that can be moved by a machine rather quickly (about 5–8 mph) in order to create a separated lane or reverse the operation of lanes on a freeway. Research Team Multimodal Facilities serving more than one transportation mode. Kuhn et al. (4) National Committee on Uniform Traffic Control Devices (NCUTCD) A volunteer organization that assists in developing standards, guides, and warrants for traffic control devices. NCUTCD recommends changes to the MUTCD to FHWA. NCUTCD (122) National Cooperative Highway Research Program (NCHRP) A program established by the American Association of State Highway Officials (now American Association of State Highway and Transportation Officials) to provide a mechanism for a national coordinated program of cooperative research employing modern scientific techniques. NCHRP is administered by the Transportation Research Board. National Academies of Sciences, Engineer- ing, and Medicine (123) National Environmen- tal Policy Act (NEPA) Legislation enacted in 1969 that requires that federally funded projects conduct an environmental impact statement to evaluate potential impacts. Kuhn et al. (4) Network 1. In planning, a system of links and nodes that describes a transporta- tion system. 2. In highway engineering, the configuration of highways that constitutes the total system. 3. In transit operations, a system of transit lines or routes, usually designed for coordinated operation. Kittelson & Associates et al. (119) Non-attainment area A geographic area in which the level of air pollution is higher than the level allowed by nationally accepted standards for one or more pollutants. Kuhn et al. (4) Off-line station Mode transfer facility located near a managed lane but not within the freeway right-of-way. Is sometimes connected to the managed lane with a grade-separated ramp. Research Team Off-peak The periods of time outside the peak periods; see also base period. Kittelson & Associates et al. (119) Off-peak direction Direction of lower demand during the peak commuting period. Kuhn et al. (4) On-line station Mode transfer facility located along a managed lane or a fixed-guideway system. (Also called in-line station in some references.) Research Team Open-road ETC lane A non-attended lane that is designed to allow toll payments to be elec- tronically collected from vehicles traveling at normal highway speeds. Typically physically separated from the toll plaza, often following the alignment of the mainline lanes, with toll plaza lanes for cash toll payments being on a different alignment after diverging from the mainline lanes or a subset thereof. FHWA (1) Term Definition Source

142 Open-road tolling A system designed to allow ETC from vehicles traveling at normal high- way speeds. Might be used on toll roads or toll facilities in conjunction with toll plazas. Also typically used on managed lanes and on toll facilities that only accept payment by ETC. FHWA (1) Open-road tolling point The location along an open-road ETC lane at which roadside or overhead detection and receiving equipment are placed and vehicles are electroni- cally assessed a toll. FHWA (1) Origin–destination study Analysis of the starting and ending points or zones of people or vehicles. Kuhn et al. (4) Paratransit Forms of transportation services that are more flexible and personalized than conventional fixed-route, fixed-schedule service but not including such exclusory services as charter bus trips. The vehicles for paratransit service are usually low- or medium-capacity highway vehicles, and the service offered is adjustable in various degrees to individual needs. Kittelson & Associates et al. (119) Park-and-pool lot Facility where individuals can park their private vehicles and join a carpool or vanpool. Not normally served by public transportation. Kuhn et al. (4) Park-and-ride (park ‘n’ ride, P&R) An access mode to transit in which patrons drive private automobiles or ride bicycles to a transit station, stop, or carpool/vanpool waiting area and park the vehicle in the area provided for that purpose (park-and-ride lot, park-and-pool lot, commuter parking lot, bicycle rack or locker). They then ride the transit system or take a carpool or vanpool to their destinations. Kittelson & Associates et al. (119) Park-and-ride lot Facility where individuals can park their private vehicles and access public transportation. Kuhn et al. (4) Parking facility An area, which may be enclosed or open, attended or unattended, in which automobiles may be left, with or without payment of a fee, while the occupants of the automobiles are using other facilities or services. Kittelson & Associates et al. (119) Parking management Strategies aimed at making better use of available parking supply. Includes preferential parking or price discounts for carpools and/or short-term parkers, and disincentives for those contributing more to congestion. Kuhn et al. (4) Parking surcharges Users who park in congested areas during the most congested periods are charged fees higher than those normally associated with the facilities they use. Kuhn et al. (4) Parking turnover The ratio of the total number of parked vehicles accommodated during a given period in a specified area to the total number of parking spaces in that area. Kittelson & Associates et al. (119) Peak direction Direction of higher demand during a peak commuting time. Kuhn et al. (4) Peak hour The hour in which the maximum demand occurs on a facility. Kuhn et al. (4) Peak-hour factor (peak-hour conversion factor) 1. The ratio of the volume during the peak hour to the maximum rate of flow during a selected period within the peak hour, usually 15 or 20 minutes. 2. The ratio of the volume during the peak hour to the volume during the peak period, usually the peak 2 hours, typically 60 percent. Kittelson & Associates et al. (119) Term Definition Source

143 Peak period Period in which traffic levels rise from normal levels to maximum levels. Kuhn et al. (4) Pedestrian A person traveling on foot. Kittelson & Associates et al. (119) Persons with disabilities Persons who have physical or mental impairments that substantially limit one or more major life activities. In the context of transportation, the term usually refers to people for whom the use of conventional transit facilities would be impossible or would create a hardship. Kittelson & Associates et al. (119) Pictograph A pictorial representation used to identify a governmental jurisdiction, an area of jurisdiction, a governmental agency, a military base or branch of service, a governmental-approved university or college, a toll payment system, or a government-approved institution. FHWA (1, Section 1A.13, Definition 146) Platform 1. The front portion of a bus or streetcar where passengers board. 2. The waiting area next to where passengers board and alight from buses or rail transit vehicles at a transit station. Research Team Preferential lane A highway lane reserved for the exclusive use of one or more specific types of vehicles or vehicles with at least a specific number of occupants. FHWA (1) Preferential parking Incentive to encourage ridesharing. Usually located closer to the destination. Kuhn et al. (4) Price 1. A fee charged for use of a road or lane. 2. The direct costs borne by users for consuming a good or service. Research Team Price elasticity of demand A measure of the sensitivity of demand for a commodity to a change in its price. It equals the percentage change in consumption of the commodity that results from a 1-percent change in its price. The greater the elasticity, the more price sensitive the demand for the commodity. Kuhn et al. (4) Pricing 1. To charge a price (or toll) for the use of a road. 2. Method used by an agency to set the price (or toll) for the use of a road. Research Team Priority lane Lane providing preferential treatment to eligible users. Research Team Priority lane pricing Concept of using congestion pricing on a managed lane. Research Team Public transit Passenger transportation service, usually local in scope, that is available to any person who pays a prescribed fare. Operates on established schedules along designated routes or lines with specific stops and is designed to move relatively large numbers of people at one time. Examples include bus, light rail, and rapid transit. Kittelson & Associates et al. (119) Public transportation Transportation service provided to the public on a regular basis using vehicles that transport more than one person for compensation, usually but not exclusively over a set route or routes from one fixed point to another. Routes and schedules of this service may be predetermined by the operator or may be determined through a cooperative arrangement. Kittelson & Associates et al. (119) Pullout A short section of pavement oriented to the left or right of the managed lane travelway or mainlanes that can serve a variety of operational purposes including enforcement and emergency refuge. Research Team Pylon See channelizer. Term Definition Source

144 Quality of service The overall measured or perceived quality of transportation service from the user’s or passenger’s point of view, rather than from the operating agency’s point of view. Defined for transit systems, route segments, and stops by level of service. Kittelson & Associates et al. (119) Queue A line of vehicles or people waiting to be served by the system in which the rate of flow from the front of the line determines the average speed within the line. Slow-moving vehicles or people joining the rear of the queue are usually considered a part of the queue. Kittelson & Associates et al. (119) Queue bypass A managed lane facility that provides a bypass around a queue of vehicles delayed at a ramp or mainline traffic meter or other bottleneck location. Research Team Queue jumper 1. A short section of exclusive or preferential lane that enables specified vehicles to bypass an automobile queue or a congested section of traffic. Often used at signal-controlled metered freeway on-ramps in congested urban areas to allow high-occupancy vehicles preference. Also known as a bypass lane or queue bypass. 2. A person who violates passenger controls. Kittelson & Associates et al. (119) Ramp control signal A highway traffic signal installed to control the flow of traffic onto a free- way at an entrance ramp or at a freeway-to-freeway ramp connection. FHWA (1) Ramp meter See ramp control signal. Ramp meter bypass Preferential treatment at a ramp meter in which a lane is provided for the exclusive use of eligible vehicles such as HOVs to bypass the queue. Kuhn et al. (4) Ramp metering Procedure used to reduce congestion by managing vehicle flow from local-access on-ramps. The entrance ramp is equipped with a traffic signal that allows vehicles to enter the freeway at predetermined intervals. Kuhn et al. (4) Rapid transit Generic term introduced in the 1890s to denote any transit that was faster than its predecessor, most particularly for the replacement of horse cars with electric streetcars; now generally used for rail systems on exclusive right-of-way (e.g., heavy rail or metro). Kittelson & Associates et al. (119) Revenue-neutral Pricing strategies that involve rebating some or all of the revenue generated by pricing to toll payers; raising money is not an objective of congestion pricing. Kuhn et al. (4) Reverse commute Travel time between work/school and home in the opposite direction of the peak direction of travel. Kuhn et al. (4) Reversible lane Facility in which the direction of traffic flow can be changed at different times of the day to match the peak direction of travel, typically inbound in the morning and outbound in the afternoon. Research Team Ridesharing A mode of travel in which two or more people share a ride using a common vehicle. Research Team Right-of-way 1. A general term denoting land, property, or interest therein, usually in a strip, acquired for or devoted to transportation purposes. For transit, rights-of-way may be categorized by degree of their separation: fully con- trolled without grade crossings, also known as grade-separated, exclusive, or private right-of-way; longitudinally physically separated from other traffic (by curbs, barriers, grade separation, etc.) but with grade crossings; or surface streets with mixed traffic, although transit may have preferential treatment. 2. The precedence accorded to one vehicle or person over another. Kittelson & Associates et al. (119) Term Definition Source

145 Right shoulder Pavement located on the right side of the managed lane travelway or general-purpose mainlanes used for enforcement and emergency stopping. Research Team Road pricing An umbrella phrase that covers all charges imposed on those who use roadways. Includes such traditional revenue sources as fuel taxes and license fees as well as charges that vary with time of day, specific road used, and vehicle size and weight. Kuhn et al. (4) Separation 1. The width between a managed lane and adjacent general-purpose lane for facilities located within a freeway. 2. The physical treatment (i.e., paint stripe, barrier, channelizers, etc.) between a managed lane and general- purpose lanes. Research Team Service, express Service that has fewer stops and a higher operating speed than regular service. Often used as an alternative term for limited-stop service; when agencies provide both types of service, the express service tends to have much longer sections of nonstop running. Kittelson & Associates et al. (119) Service, express bus Bus service with a limited number of stops, either from a collector area directly to a specific destination or in a particular corridor with stops en route at major transfer points or activity centers. Usually uses freeways or busways where they are available. Kittelson & Associates et al. (119) Service frequency The number of transit units (vehicles or trains) on a given route or line, moving in the same direction, that pass a given point within a specified interval of time, usually 1 hour; see also headway. Kittelson & Associates et al. (119) Signal preemption An interruption of the normal operation of a signal in order to immediately serve a particular movement. Kuhn et al. (4) Signal priority Technique of altering the sequence or timing of traffic signal phases using special detection in order to provide preferential treatment. Kuhn et al. (4) Simulation 1. A mathematical or conceptual presentation of traffic operational relationships and actions within a system. Used for analysis of the system or its evaluation under various conditions; an example includes traffic flow into and out of a managed lane. 2. A mathematical description of a real-life situation that uses data on past and present conditions to make a projection about future conditions. Research Team Slip ramp A designated at-grade access provided between the managed lane and general-purpose lanes. May be channelized through striping or barriers, or may be an open weave zone represented as breaks in pavement markings. Research Team Special-use lane Lane restricted for specific uses only. Kuhn et al. (4) Speed limit The maximum (or minimum) speed applicable to a section of highway as established by law or regulation. FHWA (1) Speed, advisory A recommended speed for vehicles operating on a section of highway or a specific lane based on the highway design, operating characteristics, and prevailing conditions if displayed dynamically. FHWA (1) Speed, operating The speed at which drivers are observed operating their vehicles during free-flow conditions. The 85th percentile of the distribution of observed speeds is the most frequently used measure of the operating speed. AASHTO (27) Term Definition Source

146 Speed, overall trip (effective operating speed, cycle speed) In transit operations, the average speed achieved per round trip, including layover and recovery time but excluding deadheading time. Calculated by individual trips, by running time periods, or for the entire schedule. Kittelson & Associates et al. (119) Speed, running The speed at which an individual vehicle travels over a highway section. AASHTO (27) Speed–flow relationship The relationship between the flow (volume) of units on a transportation facility and the speed of those units. As flow increases, speed tends to decrease. Kittelson & Associates et al. (119) Station An off-street facility (typically) where passengers wait for, board, alight, or transfer between transit units (vehicles or trains). Usually provides information and a waiting area and may have boarding and alighting plat- forms, ticket or farecard sales, fare collection, and other related facilities; also known as a passenger station. Kittelson & Associates et al. (119) Station, accessible A public transportation passenger facility that provides ready access, is usable, and does not have physical barriers that prohibit and/or restrict access by individuals with disabilities, including individuals who use wheelchairs. Kittelson & Associates et al. (119) Stop, far-side A stop located immediately after an intersection. Fitzpatrick et al. (124) Stop, midblock A stop within a block. Fitzpatrick et al. (124) Stop, near-side A stop located immediately before an intersection. Fitzpatrick et al. (124) Stop, transit An area where passengers wait for, board, alight, and transfer between transit units (vehicles or trains). Usually indicated by distinctive signs and by curb or pavement markings and may provide service information, shelter, seating, or any combination of these. Stops are often designated by the mode offering service, for example, bus stop or car stop. Kittelson & Associates et al. (119) Superelevation 1. In track construction, the vertical distance that the outer rail is set above the inner rail on a curve, expressed as the vertical distance of the outer rail over the inner rail or as the transverse grade percent. Permits increased operating speed on curves, cannot exceed a maximum, typically 10 percent, to allow for trains that may stop or operate at below design speed on the curve. 2. In highway construction, the banking of the roadway on a curve. Kittelson & Associates et al. (119) Support facility A physical improvement that enhances managed lane operations, usually for a specific mode (i.e., a park-and-ride lot for transit services using a managed lane). Kuhn et al. (4) Symbol The approved design of a pictorial representation of a specific traffic con- trol message for signs, pavement markings, traffic control signals, or other traffic control devices. FHWA (1, Definition 227, p. 21) Throughput The volume of vehicle or passengers passing a specific point during a pre- determined period of time. Kuhn et al. (4) Time-of-day pricing Facility tolls that vary by time of day in response to varying congestion levels. Typically, such tolls are higher during peak periods when the congestion is most severe. Kuhn et al. (4) Toll A fee charged for use of a road or lane. Research Team Term Definition Source

147 Toll lane or road A section of road where motorists are charged a usage fee that is usually collected at a specific point for a given lane or section of road. Adapted from Kuhn et al. (4) Toll zone A defined length of lane or roadway in which a specific toll is being levied, often in real time on managed lanes based on changing traffic conditions. Research Team Tolling To charge a toll (or price) for the use of a road. Research Team Traffic assignment The planning and modeling process of allocating trips by different modes and to different origins and destination and routes. Kuhn et al. (4) Traffic assignment zone The division of a study area into subunits or zones, allowing for a more detailed level of analysis. Kuhn et al. (4) Traffic control device A sign, signal, marking, or other device used to regulate, warn, or guide traffic, placed on, over, or adjacent to a street, highway, private road open to public travel, pedestrian facility, or shared-use path by authority of a public agency or official having jurisdiction, or, in the case of a private road open to public travel, by authority of the private owner or private official having jurisdiction. FHWA (1) Traffic volume The number of vehicles on a roadway. Kuhn et al. (4) Transit center Mode transfer facility serving buses or other modes such as pedestrians, kiss-and-ride patrons, rail transit, or bicyclists. Research Team Transit shelter A building or other structure constructed at a transit stop. May be des- ignated by the mode offering service, for example, bus shelter. Provides protection from the weather and may provide seating or schedule infor- mation or both for the convenience of waiting passengers. Kittelson & Associates et al. (119) Transit system, bus rapid (bus rapid transit, BRT) An inexact term describing a bus operation providing service similar to rail transit, often at a lower cost. BRT systems are characterized by several of the following components: exclusive transitways, enhanced stations, easily identified vehicles, high-frequency all-day service, simple route structures, simplified fare collection, and ITS technologies. Integrating these compo- nents is intended to improve bus speed, reliability, and identity. Kittelson & Associates et al. (119) Transitway A dedicated right-of-way or roadway used by transit vehicles (buses or trains). Kittelson & Associates et al. (119) Transponder An ETC tag mounted on a windshield or license plate, built into a vehicle, or placed on the dashboard. The tag is read electronically by an electronic tolling device that automatically assesses the amount of the user fee. The transponder function may also be provided from a smartphone or other portable device through a mobile account or application. Research Team Transportation control measure Series of vehicle trip-reduction measures focusing on reducing travel by single-occupancy vehicles and increasing alternative modes. Kuhn et al. (4) Transportation system management Actions that improve the operation and coordination of transportation services and facilities. Kuhn et al. (4) Transportation/travel demand management A variety of strategies, techniques, or incentives aimed at providing the most efficient and effective use of existing transportation services and facilities (e.g., rideshare and telecommuting promotion, managed lanes, preferential parking, road pricing, etc.). Kuhn et al. (4) Term Definition Source

148 Travel time The length of time it takes to travel between two points. Kuhn et al. (4) Travel time reliability The lack of variability in travel time that can be expected using different facilities. Kuhn et al. (4) Travel time savings Time saved by using one facility instead of another (e.g., using an HOV facility rather than the general-purpose lanes). Kuhn et al. (4) Travelway The main lane or roadway of a managed lane. Research Team Trip 1. A one-way movement of a person or vehicle between two points for a specific purpose; sometimes called a one-way trip to distinguish it from a round trip. 2. The movement of a transit unit (vehicle or train) in one direction from the beginning of a route to the end of it; also known as a run. Kittelson & Associates et al. (119) Trip generation rates Number of vehicular trips to and from a development. Are used to identify the potential impacts of new projects. Kuhn et al. (4) Truck lanes Dedicated lanes restricted or primarily dedicated to the movement of large commercial trucks. Kuhn et al. (4) User management The types of users who can utilize a facility. HOV lanes are prime examples of user-managed facilities. Restrictions may vary by time of day or day of the week. Kuhn et al. (4) Value pricing A system of fees or tolls paid by drivers to gain access to dedicated roadway facilities providing a superior level of service compared to the competitive free facilities. Permits anyone to access the managed lanes, and the value of the toll is used to ensure that the management goals of the facility are maintained. Kuhn et al. (4) Van Vehicles having a typical seating capacity of 5 to 15 passengers and classi- fied as a van by vehicle manufacturers. A modified van is a standard van that has undergone some structural changes, usually made to increase its size and particularly its height. The seating capacity of modified vans is approximately 9 to 18 passengers. Kittelson & Associates et al. (119) Vanpool Vans and/or buses seating fewer than 25 persons operating as a voluntary commuter ridesharing arrangement, which provides transportation to a group of individuals traveling directly between their homes and their regular places of work within the same geographical area. The vans should have a seating capacity greater than seven persons, including the driver. A mass transit service operated by a public entity, or in which a public entity owns, purchases, or leases the vehicles. Kittelson & Associates et al. (119) Variable pricing Tolls that are collected to manage demand, either dynamically in response to changing traffic conditions or in accordance with a daily schedule that reflects changing traffic conditions (in some references also called value pricing). Research Team Vehicle miles traveled The total distance traveled in miles by all motor vehicles of a specific group in a given area at a given time. Kuhn et al. (4) Vehicle occupancy The number of people aboard a vehicle at a given time; also known as auto or automobile occupancy when the reference is to automobile travel only. Kittelson & Associates et al. (119) Term Definition Source

149 Vehicle-to- infrastructure communications A system designed to transmit information between vehicles and the road infrastructure to enable a variety of safety, mobility, and environmental applications. FHWA (18) Vehicle-to-vehicle communications A system designed to transmit basic safety information between vehicles to facilitate warnings to drivers concerning impending crashes. FHWA (18) Vertical clearance The distance between the surface of the roadway and an overhead structure that provides the basis for meeting different design vehicle requirements. Research Team Violation An infraction by users against formal rules and restrictions associated with a managed lane. Research Team Violation rate (occupancy) Number of vehicles that do not meet the minimum occupancy require- ments on an HOV lane divided by total vehicles passing a given point or section of roadway. Research Team Violation rate (toll) Number of vehicles who are subject to tolling that are not paying or are evading the toll divided by the total passing a given point or section of roadway. Research Team Volume In transportation, the number of units (passengers or vehicles) that pass a point on a transportation facility during a specified interval of time, usually 1 hour. Kittelson & Associates et al. (119) Volume-to-capacity ratio The ratio of demand flow rates to capacity for a given type of transportation facility. Kuhn et al. (4) Term Definition Source

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Guidelines for Implementing Managed Lanes Get This Book
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TRB's National Cooperative Highway Research Program (NCHRP) Report 835: Guidelines for Implementing Managed Lanes provides guidance for transportation agencies interested in designing, implementing, operating, and maintaining managed lanes. Guidance includes ways to define initial objectives, outline the necessary decision-making process, and address safety concerns, through the process of detailed design configuration and operation.

The contractor’s final report, NCHRP Web-Only Document 224: Research Supporting the Development of Guidelines for Implementing Managed Lanes, includes detailed background material, gap analysis, design elements, safety performance parameters, and additional related information that emerged through the case studies.

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