APPENDIX A

Glossary

Adjusted flow rates—The maximum rate of flow adjusted for traffic conditions, traffic composition, roadway geometry, and other factors.

Airfield licenses—Licenses or permits required to operate a vehicle on an airfield at major airports.

Airport curbside—The one-way roadways located immediately in front of the terminal buildings where vehicles stop to pick up and drop off airline passengers and their baggage.

Air taxi—A for-hire passenger or cargo aircraft that operates on an unscheduled basis.

Automatic traffic recorder machines—Equipment, often portable, that records the traffic volume crossing a tube or detector.

Automatic vehicle identification (AVI)—A system or Radio-Frequency-Identification equipment (i.e., vehicle-mounted tags or transponders) commonly used on roadways and bridges to collect tolls.

Auxiliary lane—A supplementary lane intended to facilitate weaving or merging vehicle movements.

Bypass lanes—Curbside lanes intended for use by vehicles bypassing or not stopping at a curbside section or zone.

Bypass vehicles—Vehicles traveling past, but not stopping in, a curbside section or zone including vehicles recirculating past the curbside, vehicles traveling to/from adjacent curbside zones, or service/delivery vehicles using the curbside roadway.

Cell phone lots or call-and-wait lots—Free parking lots, typically located away from the terminal area, provided for use by motorists waiting to pick up deplaning airline passengers.

Commercial vehicles—Vehicles transporting airline passengers (including taxicabs, limousines, courtesy vehicles, buses, and vans), driven by professional drivers, for which passengers pay a fee or for which the transportation is incidental to the service provided (e.g., a hotel courtesy vehicle).

Cost paths—A person’s perception of the cost that would be incurred while traveling along a defined path or route, typically including their value of time.

Courtesy vehicle—Door-to-door, shared-ride transportation provided by the operators of hotels/motels, rental car companies, parking lots, and other services solely for their customers.

Critical movement analysis—Calculation of the lanes or movements requiring the most “green” time at a signalized intersection and, therefore, a method of estimating intersection capacity.

Critical volumes—The volume or combination of volumes (e.g., conflicting movements) that produces the highest demand for an intersection lane or signal phase.

Curbside geometries—The horizontal and vertical alignment features of a curbside roadway including lane widths, grades, curvature, and crosswalks.

Customs and Border Protection (CBP)—The U.S. government agency responsible, among other duties, for inspection of international arriving passengers and goods to collect import duties and prevent importation of illegal goods.

Decision-making distance—The physical distance between successive decision points.

Decision points—The physical location where a driver must select between alternative paths or roadways.

Deplaned passengers—Passengers alighting from an aircraft at an airport including both connecting and terminating airline passengers.

Discount factor—An adjustment applied to reduce the effective capacity of curbsides having an unusual configuration, location, or operation.

Double-parking—Two or more parallel parked or standing vehicles.

Driver population factor—A factor applied to roadway capacities to reflect driver behavior and operating characteristics including familiarity with roadways, intersections, and traffic patterns.

Electronic ticketing kiosks—A self-serve machine used by airline passengers to print boarding passes and other documents.

Enplaned passengers—Passengers boarding an aircraft at an airport including both connecting and originating airline passengers.

Equivalent passenger-car volumes—A hypothetical passenger-car volume representing an actual volume composed of a mix of trucks, buses, and other vehicle sizes in the traffic stream.

Fixed-base operator—An aviation business that serves general aviation aircraft owners and operators with services including fueling, catering, aircraft maintenance, and storage.

Flattening the peak—A reduction in the proportion of demand occurring in a 15-minute or hourly interval due to demand management, changes in schedules, demands approaching capacity, or other causes.

Flow rate—As used in this Guide, the volume of vehicles or people passing a point per unit of time such as vehicles per hour.

Free-flow speed—The mean speed of traffic under very light flow conditions.

General aviation—All flights (or aircraft operations) other than scheduled/commercial-service or military flights.

Green time—The portion of a traffic control signal phase during which vehicles are permitted to flow (i.e., the green signal is displayed).

Growth factor—A factor applied to passenger or traffic volumes, for example, to adjust for anticipated future growth.

Heavy vehicle factor—A factor applied to roadway capacities to reflect the proportion of large vehicles (e.g., large trucks and buses) in the traffic stream.

Highway capacity analysis procedures—Analysis conducted using the procedures described in the Highway Capacity Manual.

Highway Capacity Manual (HCM)—The HCM, published by the Transportation Research Board (7th edition published in 2022).

Immigration and Customs Enforcement—The U.S. government agency responsible for, among other duties, inspection of international arriving passengers and crew prior to their entering the country.

Intelligent transportation system (ITS)—Information and communication technologies applied to transportation infrastructure and vehicles to improve operations, safety, and efficiency.

Lag time—The length of time after their flight’s scheduled arrival time that a passenger gets to the airport curbside.

Landside circulation system—The airport roadway network providing for inbound and outbound traffic and the internal circulation of traffic between airport land uses.

Lane balance—The number of lanes entering and exiting a roadway merge or diverge point.

Lane geometry—The horizontal and vertical alignment features of a roadway or roadway lane including lane widths, grades, lengths, curvatures, tapers, and other physical features.

Lateness distribution—The distribution of passengers leaving an airport after the scheduled arrival time of their aircraft (i.e., a distribution of passenger lag times).

Lead time—The length of time in advance of their flight’s scheduled departure time that a passenger arrives at the airport curbside (as used in this Guide).

Macroscopic models—Models or analytical procedures that consider the flow of vehicle streams (or other objects) rather than the flow of individual vehicles.

Manual on Uniform Traffic Control Devices (MUTCD)—The principal standard governing the application, design, and placement of traffic control devices, published by the FHWA. See http://Mutcd.fhwa.dot.gov.

Maximum service flow—A maximum rate at which vehicles can transverse a point or short segment during a specified time period.

Merging capacity—Maximum service rate at a merge point.

Metropolitan planning organization (MPO)—A policy-making organization responsible for planning, analyses, and development of multimodal transportation facilities in a region or community.

Microsimulation—Models or analytical procedures that simulate the operation of individual vehicles (or other objects) on simulated roadway (or other) networks.

Mixed flow traffic volumes—A traffic flow consisting of multiple types of vehicles.

Operational characteristics—Traffic flow characteristics including speed, density, vehicle mix, and volumes.

Passenger load factor—A measure of the historical proportion of the available aircraft seats that are occupied.

Peak-hour factor—The relationship between the hourly volume and the maximum 15-minute flow rate within the hour.

Performance capabilities—As used in this Guide, refers to the performance capabilities of an individual vehicle or group of vehicles including acceleration, maneuverability, and turning radii.

Poisson distribution—A discrete probability distribution that expresses the probability of a number of events occurring in a fixed period of time.

Remote curbside—A curbside located outside of the immediate area of the passenger terminal building such as in a parking structure, surface lot, or multimodal facility.

Rental car ready/return—The parking or storage area(s) to which rental car customers return “dirty” vehicles or pick up “ready” vehicles.

Signal phasing—The part of a traffic control signal time cycle allocated to any traffic movement receiving the right-of-way.

Skycap—A porter employed by an airline or airport to provide baggage service to passengers.

Steady-state performance—The traffic flow rates occurring on a roadway or intersection when there are no disruptions or interruptions to the traffic stream.

Terminal area roadway—The roadways serving the terminal building and surrounding areas including access, curbside, and circulation roadways.

Through vehicles—As used in this Guide, vehicles bypassing the curbside area or zone. (See bypass vehicles.)

Time path—A person’s perception of the time that would be incurred while traveling along a defined path or route including time in motion, delays due to congestion, and waiting time.

Traffic controls—Devices directing vehicular and pedestrian traffic flows, particularly at conflict areas, including signals, signs, and pavement markings.

Transportation demand management—The application of policies and strategies to reduce travel demand or redistribute this demand in space or time.

Transportation network company (TNC)—A company providing pre-arranged transportation services for compensation using an online application or platform (such as smartphone applications) to connect drivers using their personal vehicles with passengers.

Trip generation rate—The number of vehicle or person trips generated by a household, zone, land use, or other facility generally during a daily or peak-period basis.

Triple-parking—Three or more parallel parked or standing vehicles.

Waybill—A list of passengers or goods being carried on a vehicle, often containing details about the arrival time, destination, and other information about the passengers or goods.

Weaving areas—The roadway segment in which two or more traffic streams traveling in the same general direction along a significant length of roadway cross without the aid of traffic control devices.

Weaving distance—The length of a weaving area or segment.

Weaving intensity factor—A measure of the influence of weaving activity on the average speed of both weaving and non-weaving vehicles.

Vehicle mix—The proportion of each type of vehicle (i.e., bus, car, van, truck) in a traffic stream.

Vehicle occupancy—The number of passengers (including the driver) in a vehicle.

Vehicle stall length—The length of curb space occupied by a standing vehicle including the distance required to maneuver into and out of the space.