BTS | Dictionary

Daily Average Flow: The volume of gas that moves through a section of pipe determined by dividing the total annual volume of gas that moves through a section of pipe by 365 days. Volumes are expressed in million cubic feet per day measured at a pressure of 14.73 psia and a temperature of 60 degrees Fahrenheit. For pipes that operate with bidirectional flow, the volume used in computing the average daily flow rate is the volume associated with the direction of flowing gas on the peak day. (DOE1)

Daily Vehicle Travel: Is the amount of vehicle travel (in thousands) accumulated over a 24-hour day, midnight to midnight, traversed along a "public road" by motorized vehicles, excluding construction equipment or farm tractors. Vehicle travel not occurring on public roads, such as that occurring on private land roads (private roads in parking lots, shopping centers, etc.) must be also be excluded. (FHWA2)

DAIR: Direct Altitude and Identity Readout (FAA4)

DAL: Dallas Love Field (FAA11)

Dam: A barrier constructed across a watercourse to control the flow or raise the level of water. (DOI4)

Dam Bulletin Board: A bulletin board located at certain dams to give stage readings and indicate whether to use lock or go over the dam. "N.P." means use the lock. "P" means go over the dam. Largely obsolete in use since the advent of radio communications. (TNDOT1)

Dam Open: The situation when the gates are open so as to pass water unimpeded. (TNDOT1)

Dam Warning Buoys: Buoys placed above the face of a dam to warn traffic of danger. These buoys may be of peculiar shape and generally have the word "danger" posted on them. (TNDOT1)

Dam/Weir: A barrier constructed to control the flow or raise the level of water. (DOI3)

Danger Area: An airspace of defined dimensions within which activities dangerous to the flight of aircraft may exist at specified times. Note: The term "Danger Area" is not used in reference to areas within the United States or any of its possessions or territories. (FAA4)

Danger Signal: Four or more short blasts of the boat's or lockmaster's whistle to indicate danger or the need for special caution. (TNDOT1)

DAR: Dial-A-Ride (TRB1)

DARC: Direct Access Radar Channel (FAA19)

DART: Dallas Area Rapid Transit (FHWAII)

DASCAR: Data Acquisition System for Crash Avoidance Research (NHTSA5)

DASI: Digital Altimeter Setting Indicator (FAA19)

Datum: Reference point for elevations of structures and water level. (TNDOT1)

Day: From 6 a.m. to 5:59 p.m. (NHTSA3)

DAY: James M Cox Dayton International Airport (FAA11)

Daymark: An unlighted shore aid to navigation, either diamond, square, or triangle shaped. (TNDOT1)

DB: Decibel (BTS8)

DBN: Day Beacon (USCG5)

DBRITE: Digital Bright Radar Indicator Tower Equipment (FAA19) (FAA8)

DC: Direct Current (FAA19)

DCA: Washington National Airport (FAA11)

DCC: Display Channel Complex (FAA19)

DCM: Dangerous Cargo Manifest (RSPA1)

DDPS: Dual Driver Protective Service (MTMC1)

DDT: Deflagration-To-Detonation Transition (RSPA1)

Dead Axle: Non powered rear axle on tandem truck or tractor. (ATA1)

Dead Freight: The freight charges paid by the charterer of a vessel for contracted space which is left partially unoccupied. (TNDOT1)

Dead Heading: Running empty. (ATA1)

Dead Locomotive: A locomotive other than a control cab locomotive that does not have any traction device supplying tractive power; or a control cab locomotive that has a locked and unoccupied cab. (49CFR229)

Dead Reckoning: As applied to flying, the navigation of an airplane solely by means of computations based on airspeed, course, heading, wind direction, speed, groundspeed, and elapsed time. (FAA4)

Dead Section: A section of track, either within a track circuit or between two track circuits, the rails of which are not part of a track circuit. (49CFR236)

Deadhead: Miles and hours that a vehicle travels when out of revenue service. This includes leaving and returning to the garage, changing routes, etc., and when there is no reasonable expectation of carrying revenue passengers. However, it does not include charter service, school bus service, operator training, maintenance training, etc. For non-scheduled, non-fixed-route service (demand responsive), deadhead mileage also includes the travel between the dispatching point and passenger pick-up or drop-off. (FTA1)

Deadhead: 1) Any water-soaked wooden pile, tree, or log that is floating just awash in a nearly vertical position. A menace to small boats and to the propellers of vessels. 2) A tow returning from a trip without barges or with empty barges. (TNDOT1)

Deadhead Transportation: Occurs when an employee is traveling at the direction or authorization of the carrier to or from an assignment, or the employee is involved with a means of conveyance furnished by the carrier or compensated for by the carrier. (FRA2)

Deadman Control: A pedal, handle, or other form of switch, or combination thereof, that the operator must keep in a depressed or twisted position while a rail vehicle (or train) is moving. If the control is released, the power is cut off and the brakes are applied. (TRB1)

Deadweight Tons: The lifting capacity of a ship expressed in long tons (2,240 lbs.), including cargo, commodities, and crew. (DOE5)

DEC: Drug Evaluation and Classification (NHTSA6)

Decision Height (DH): With respect to the operation of aircraft, means the height at which a decision must be made, during an Instrument Landing System (ILS) or Precision Approach Radar (PAR) instrument approach, to either continue the approach or to execute a missed approach. (14CFR1)

Deck Plate: A horizontal surface designed to provide a person with stable footing for the performance of work such as the connection and disconnection of air and electrical lines, gaining access to permanently-mounted equipment or machinery or for similar needs. (49CFR399)

Decoder: (See also Code; Discrete Code) The device used to decipher signals received from Air Traffic Control Radar Beacon System (ATCRBS) transponders to effect their display as select codes. (FAA4)

Dedicated Funds: Any funds raised specifically for transit purposes and which are dedicated at their source (e.g., sales taxes, gasoline taxes, and property taxes), rather than through an allocation from the pool of general funds. (FTA1)

Dedicated Tow: A single commodity moved from origin to destination by the same towboat without picking up or dropping off other barges. Often used in the movement of grain, coal, and bulk liquid. (TNDOT1)

Deep Sea Domestic Transportation of Freight: Establishments primarily engaged in operating vessels for transportation of freight on the deep seas between ports of the United States, the Panama Canal Zone, Puerto Rico, and United States island possessions or protectorates. (BOC1)

Deep Sea Transportation of Passengers: Establishments primarily engaged in operating vessels for the transportation of passengers on the deep seas except by ferry. (BOC1)

Defect Notification System: A computerized system that enables the Coast Guard to monitor the efforts of boat and equipment manufacturers in complying with 46 U.S.C. 4310. (USCG1)

Defense Visual Flight Rules (DVFR): Rules applicable to flights within an Air Defense Identification Zone conducted under the visual flight rules in Federal Aviation Regulation, Part 91. (FAA2) (FAA4) (FAA13)

Deferred Credits: Items for which additional information or events are required to determine their ultimate disposition and accounting classification, including deferred taxes, deferred investment tax credits, and other suspense items. (BTS4)

Deferred Income Taxes: Tax effects which are deferred for allocation to income tax expense of future periods. (BTS4)

Deferred Investment Tax Credits: Investment tax credits deferred for amortization over the service life of the related equipment. (BTS4)

Defined Mandatory Use Service Area: That listed in the determination of each Fleet Management Center or Fleet Management Subcenter. (GSA2)

Degree of (Critical) Hazard: A situation in which collision avoidance was due to chance rather than an act on the part of the pilot. Less than 100 feet of aircraft separation would be considered critical. (FAA10)

Degree of (No Hazard) Hazard: A situation in which direction and altitude would have made a midair collision improbable regardless of evasive action taken. (FAA10)

Degree of (Potential) Hazard: An incident which would have resulted in a collision if no action had been taken by either pilot. Closest proximity of less than 500 feet would usually be required in this case. (FAA10)

Delay: Delays are incurred when any action is taken by a controller that prevents an aircraft from proceeding normally to its destination for an interval of 15 minutes or more. This includes actions to delay departing, enroute, or arriving aircraft as well as actions taken to delay aircraft at departing airports due to conditions en route or at destination airports. (FAA3)

Delay Indefinite (Reason If Known) Expect Further Clearance (Time): Used by Air Traffic Control (ATC) to inform a pilot when an accurate estimate of the delay time and the reason for the delay cannot immediately be determined; (e.g., a disabled aircraft on the runway, terminal or center area saturation, weather below landing minimums, etc). (FAA4)

Delay Time: As applied to an automatic train stop or train control system, the time which elapses after the onboard apparatus detects a more restrictive indication until the brakes start to apply. (49CFR236)

Delay Time: The amount of time that the arrival must lose to cross the meter fix at the assigned meter fix time. This is the difference between Actual Calculated Landing Time (ACLT) and Vertex Time of Arrival (VTA). (FAA4)

Deliverability: Represents the number of future years during which a pipeline company can meet its annual requirements for its presently certificated delivery capacity from presently committed sources of supply. The availability of gas from these sources of supply shall be governed by the physical capabilities of these sources to deliver gas by the terms of existing gas-purchase contracts, and by limitations imposed by State or Federal regulatory agencies. (DOE5)

Delivered: The physical transfer of natural, synthetic, and/or supplemental gas from facilities operated by the responding company to facilities operated by others or to consumers. (DOE5)

Delivered Energy: The amount of energy delivered to the site (building); no adjustment is made for the fuels consumed to produce electricity or district sources. This is also referred to as net energy. (DOE5)

Demand Air Taxi: Use of an aircraft operating under Federal Aviation Regulations, part 135, passenger and cargo operations, including charter and excluding commuter air carrier. (FAA9)

Demand Response: Non-fixed-route service utilizing vans or buses with passengers boarding and alighting at pre-arranged times at any location within the system's service area. Also called "Dial-a-Ride." (APTA1)

Demand Response: Passenger cars, vans or Class C motor buses operating in response to calls from passengers or their agents to the transit operator, who then dispatches a vehicle to pick the passengers up and transport them to their destinations. A demand response operation is characterized by the following: 1) the vehicles do not operate over a fixed route or on a fixed schedule except, perhaps, on a temporary basis to satisfy a special need; and 2) typically, the vehicle may be dispatched to pick up several passengers at different pick-up points before taking them to their respective destinations and may even be interrupted en route to these destinations to pick up other passengers. (FTA1)

Demand Response: Personal transit service operated on roadways to provide service on demand. Vehicles are normally dispatched and used exclusively for this service. (FTA2)

Demand Responsive System: Any system of transporting individuals, including the provision of designated public transportation service by public entities and the provision of transportation service by private entities, including but not limited to specified public transportation service, which is not a fixed route system. (49CFR37)

DEMSTAT: Deployment / Employment / Mobilization Status System (MTMC1)

Demurrage: In domestic U.S. transportation, a penalty charge against shippers or consignees for delaying the carrier's equipment beyond the allowed free time provision of the tariff at the rail ramp ; in international transportation, a storage charge to shippers which starts accruing after a container is discharged from a vessel. The charge varies according to rules of the appropriate tariff. (MARAD2)

DEN: Stapleton International Airport (FAA11)

Department of Transportation (DOT): Establishes the nation's overall transportation policy. Under its umbrella there are ten administrations whose jurisdictions include highway planning, development and construction; urban mass transit; railroads; aviation; and the safety of waterways, ports, highways, and oil and gas pipelines. The Department of Transportation (DOT) was established by act of October 15, 1966, as amended (49 U.S.C. 102 and 102 note), "to assure the coordinated, effective administration of the transportation programs of the Federal Government" and to develop "national transportation policies and programs conducive to the provision of fast, safe, efficient, and convenient transportation at the lowest cost consistent therewith." (OFR1)

Departure Angle: The smallest angle, in a plane side view of an automobile, formed by the level surface on which the automobile is standing and a line tangent to the rear tire static loaded radius arc and touching the underside of the automobile rearward of the rear tire. (49CFR523)

Departure Center: The air route traffic control center having jurisdiction for the airspace that generates a flight to the impacted airport. (FAA4)

Departure Control: A function of an approach control facility providing air traffic control service for departing Instrument Flight Rules (IFR) and, under certain conditions, Visual Flight Rules (VFR) aircraft. (FAA4)

Departure Time: The time an aircraft becomes airborne. (FAA4)

Depreciation and Amortization: All depreciation and amortization expenses applicable to owned or leased property and equipment including that categorized as flight equipment or ground property and equipment. (BTS4)

Derailment: See also Accident, Casualty, Collision, Crash, Event, Fatality, Incident, Injury.

Derailment: A derailment occurs when one or more than one unit of rolling stock equipment leaves the rails during train operations for a cause other than collision, explosion, or fire. (FRA3)

Derailment/Bus Going Off Road: A non-collision incident which occurs as a result of rolling equipment leaving the rail, or buses leaving the roadway, and for roll overs. Report all incidents regardless of severity. (FTA1)

Derailment/Left Roadway: A non-collision incident in which a transit vehicle leaves the rails or road on which it travels. This also includes rollovers. Reports are made for all occurrences. (FTA2)

Deregulation: Revisions or complete elimination of economic regulations controlling transportation. For example, the Motor Carrier Act of 1980 and the Staggers Act of 1980 revised the economic controls over motor carriers and railroads. (MARAD1)

Descent Speed Adjustments: Speed deceleration calculations made to determine an accurate vertex time of arrival (VTA). These calculations start at the transition point and use arrival speed segments to the vertex. (FAA4)

Design Capacity: (See also Certified Capacity) Is the capacity associated with the direction of the flow observed on the peak day. (DOE1)

Design Head: The achieved river, pondage, or reservoir surface height (forebay elevation) that provides the water level to produce the full flow at the gate of the turbine in order to attain the manufacturer's installed nameplate rating for generation capacity. (DOE5)

Design Live Road: The live road that the structure was designed to carry (85 psf, H-10, H-15, and HS-20). (DOI2)

Design Speed: Design speed determines the maximum degree of road curvature and minimum safe stopping, meeting, passing, or intersection sight distance. (DOI2)

Designated Area: The Fleet Management Center location as defined in the applicable determination. (GSA2)

Designated Associated Equipment: Inboard Engine, Outboard Engine, and Stern Drive Unit. Specific equipment, besides completed boats, which has been designated in 33 (CFR) 179.03 as being subject to the requirements of 46 (U.S.C.) 4310. Other items of associated equipment may be the cause for recall of boats, but the manufacturers of those items of associated equipment are not subject to the requirement for recall. (USCG1)

Designated Facility: A hazardous waste treatment, storage, or disposal facility that has been designated on the manifest by the generator. (49CFR171)

Designated Public Transportation: Transportation provided by a public entity (other than public school transportation) by bus, rail, or other conveyance (other than transportation by aircraft or intercity or commuter rail transportation) that provides the general public with general or special service, including charter service, on a regular and continuing basis. (49CFR37)

Designated Seating Capacity: The number of designated seating positions provided. (49CFR571)

Designated Seating Position: Any plan view location capable of accommodating a person at least as large as a 5th percentile adult female, if the overall seat configuration and design and vehicle design is such that the position is likely to be used as a seating position while the vehicle is in motion, except for auxiliary seating accommodations such as temporary or folding jump seats. Any bench or split-bench seat in a passenger car, truck or multipurpose passenger vehicle with a Gross Vehicle Weight Rating (GVWR) less than 10,000 pounds, having greater than 50 inches of hip room (measured in accordance with Society of Automotive Engineers (SAE) Standard J1100a) shall have not less than three designated seating positions, unless the seat design or vehicle design is such that the center position cannot be used for seating. (49CFR571)

Designated Service: Exclusive operation of a locomotive under the following conditions; 1) The locomotive is not used as an independent unit or the controlling unit is a consist of locomotives except when moving for the purpose of servicing or repair within a single yard area; 2) The locomotive is not occupied by operating or deadhead crews outside a single yard area; and 3) The locomotive is stenciled "Designated Service-DO NOT OCCUPY". (49CFR223)

Destination: For travel period trips, the destination is the farthest point of travel from the point of origin of a trip of 75 miles or more one-way. For travel day trips, the destination is the point at which there is a break in travel. (FHWA3)

Destination: The country in which the cargo was unloaded and/or the transit terminated. (SLSDC1)

Determination: A document signed by the Administrator of the General Services Administration, setting forth the decision to establish an Interagency Fleet Management Center at a specific location. (GSA2)

Detresfa (Distress Phase): The code word used to designate an emergency phase wherein there is reasonable certainty that an aircraft and its occupants are threatened by grave and imminent danger or require immediate assistance. (FAA4)

Devanning: The unloading of a container or cargo van. (MARAD2)

Deviation: 1) A departure from a current clearance, such as an off course maneuver to avoid weather or turbulence. 2) Where specifically authorized in the FARs and requested by the pilot, Air Traffic Control (ATC) may permit pilots to deviate from certain regulations. (FAA4)

DEWIZ: Distance Early Warning Identification Zone (FAA4) (FAA8)

DF: Direction Finder (FAA4) (FAA7) (FAA19) (FAA8)

DFRIF: Defense Freight Rail Interchange Fleet (MTMC1)

DFW: Dallas / Fort Worth International Airport (FAA11)

DGPS: Differential Global Positioning System (FAA17) (MARAD4)

DH: Decision Height (FAA4) (FAA17)

DHHS: Department of Health and Human Services (NHTSA6)

Dial Up Access Terminal (DUAT): The capability for direct user access terminals to file flight plans into the National Airspace System (NAS) and access weather information from the National Graphic Weather Display System. (FAA8)

Dial-A-Ride: Another name for "Demand Response." (APTA1)

DIAP: Drug Interdiction Assistance Program (FHWA10)

Diesel Fuel: (See also Diesel Fuel System) A fuel composed of distillates obtained in petroleum refining operation or blends of such distillates with residual oil used in motor vehicles. The boiling point and specific gravity are higher for diesel fuels than for gasoline. (DOE4)

Diesel Fuel System: (See also Carburetor, Diesel Fuel, Fuel Injection) Diesel engines are internal combustion engines that burn diesel oil rather than gasoline. Injectors are used to spray droplets of diesel oil into the combustion chambers, at or near the top of the compression stroke. Ignition follows due to the very high temperature of the compressed in-take air, or to the use of "glow plugs," which retain heat from previous ignitions (spark plugs are not used). Diesel engines are generally more fuel efficient than gasoline engines, but must be stronger and heavier due to high compression ratios. (DOE4)

Diesel Fuel, No 1.: A volatile distillate fuel oil with a boiling range between 300 and 575 degrees Fahrenheit and used in high-speed diesel engines generally operated under wide variations in speed and load. Includes type C-B diesel fuel used for city buses and similar operations. Properties are defined in American Society for Testing and Materials (ASTM) Specification D 975. (DOE2)

Diesel Fuel, No 2.: A gas oil type distillate of lower volatility with distillation temperatures at the 90-percent point between 540 and 640 degrees Fahrenheit for use in high speed diesel engines generally operated under uniform speed and load conditions. Includes Type R-R diesel fuel used for railroad locomotive engines, and Type T-T for diesel-engine trucks. Properties are defined in American Society for Testing and Materials (ASTM) Specification D 975. (DOE2)

Diesel-Electric Plant: A generating station that uses diesel engines to drive its electric generators. (DOE5)

Differential: An amount added or deducted from base rate to make a rate to or from some other point or via another route. (MARAD2)

Differential (Standard Type): The gear assembly on the drive axle that permits the wheels to turn at different speeds; no-slip or limited-slip type: a gear assembly on the drive axle that will not permit one wheel to spin while the other is motionless. (TII1) (TII2)

Digital Brite Radar Indicator Tower Equipment (DBRITE): Alphanumeric display systems for control towers using digital scan converter systems in a radar scope-type presentation. (FAA8)

Dike: (See also Hurdle) A construction, usually of piling or stone and usually at right angles to the current, for the purpose of diverting the river current away from the banks and toward the channel. A dike serves the same purpose as a wingdam. Dike pilings are usually visible at normal water stages but are often submerged in high water and constitute a navigational hazard. (TNDOT1)

Dike Light: A light installed on the end of a dike, normally a portable 90 mm battery-operated light. (TNDOT1)

DINK: Dual Income, No Kids

Dinner Bucket Boat: A boat operating without benefit of a cook house. (TNDOT1)

Direct: Straight line flight between two navigational aids, fixes, points, or any combination thereof. When used by pilots in describing off-airway routes, points defining direct route segments become compulsory reporting points unless the aircraft is under radar contact. (FAA4)

DIRECT: Driver Information Experimenting with Communication Technology (FHWA15)

Direct Altitude and Identity Readout System: System is a modification to the AN/TPX42 Interrogator System. The Navy has two adaptations of the DAIR System-Carrier Air Traffic Control Direct Altitude and Identification Readout System for Aircraft Carriers and Radar Air Traffic Control Facility Direct Altitude and Identity Readout System for land-based terminal operations. The DAIR detects, tracks, and predicts secondary radar aircraft targets. Targets are displayed by means of computer-generated symbols and alphanumeric characters depicting flight identification, altitude, ground speed, and Right plan data. The DAIR System is capable of interfacing with ARTCC's. (FAA4)

Direct Assistance: Transportation and other relief services provided by a motor carrier or its driver(s) incident to the immediate restoration of essential services (such as, electricity, medical care, sewer, water, telecommunications, and telecommunication transmissions) or essential supplies (such as, food and fuel). It does not include transportation related to long-term rehabilitation of damaged physical infrastructure or routine commercial deliveries after the initial threat to life and property has passed. (49CFR390)

Direct Transit Passengers: Passengers stopping temporarily at a designated airport and departing on an aircraft with the same flight number. They are counted only once. (ACI1)

Direct User Access Terminal System (DUATS): An automated pilot self-briefing and flight plan filing system. For pilots with access to a computer, modem, and touch telephone, the system provides direct access to a national weather data base and the ability to file flight plans without contact with a flight service station. (FAA14)

Direction Finder (DF): A radio receiver equipped with a directional sensing antenna used to take bearings on a radio transmitter. Specialized radio direction finders are used in aircraft as air navigation aids. Others are ground-based, primarily to obtain a "fix" on a pilot requesting orientation assistance or to locate downed aircraft. A location "fix" is established by the intersection of two or more bearing lines plotted on a navigational chart using either two separately located Direction Finders to obtain a fix on an aircraft or by a pilot plotting the bearing indications of his Direction Finder (DF) on two separately located ground-based transmitters both of which can be identified on his chart. (FAA4) (FAA8)

Direction Finder (DF) Approach Procedure: Used under emergency conditions where another instrument approach procedure cannot be executed. Direction Finder (DF) guidance for an instrument approach is given by Air Traffic Control (ATC) facilities with DF capability. (FAA4)

Direction Finder (DF) Fix: The geographical location of an aircraft obtained by one or more direction finders. (FAA4)

Direction Finder (DF) Guidance: Headings provided to aircraft by facilities equipped with direction finding equipment. These headings, if followed, will lead the aircraft to a predetermined point such as the Direction Finder (DF) station or an airport. DF guidance is given to aircraft in distress or to other aircraft which request the service. Practice DF guidance is provided when workload permits. (FAA4)

Directional Route Miles: The mileage in each direction over which public transportation vehicles travel while in revenue service. It is computed with regard to direction but without regard to the number of traffic lanes or rail tracks existing in the ROW. (FTA1)

Disabling Damage: Damage which precludes departure of a motor vehicle from the scene of the accident in its usual manner in daylight after simple repairs. (49CFR390)

Disabling Injury: An injury causing death, permanent disability or any degree of temporary total disability beyond the day of the injury. (NSC1)

Disc Brake: A brake used primarily on rail passenger cars that uses brake shoes clamped by calipers against flat steel discs. (TRB1)

Discontinued Operations Income (Loss): Gain or loss from disposal of investor controlled companies or nontransport ventures. Does not include earnings or losses from discontinued transport or transport-related operations. (BTS4)

Discrete Code: (See also Code; Decoder) As used in the Air Traffic Control Radar Beacon System (ATCRBS), any one of the 4096 selectable Mode 3/A aircraft transponder codes except those ending in zero ; e.g., discrete codes: 0010, 1201, 2317, 7777; nondiscrete codes: 0100, 1200, 7700. Nondiscrete codes are normally reserved for radar facilities that are not equipped with discrete decoding capability and for other purposes such as emergencies (7700), Visual Flight Rules (VFR) aircraft (1200), etc. (FAA4)

Discrete Frequency: A separate radio frequency for use in direct pilot-controller communications in air traffic control which reduces frequency congestion by controlling the number of aircraft operating on a particular frequency at one time. Discrete frequencies are normally designated for each control sector in en route/terminal Air Traffic Control (ATC) facilities. Discrete frequencies are listed in the Airport/Facility Directory and the Department of Defense (DOD) FLIP Instrument Flight Rules (IFR) En Route Supplement. (FAA4)

Dispatch Point: A location where arrangements may be made for the short term or trip rental use of an Interagency Fleet Management System (IFMS) vehicle. (GSA2)

Dispatch Vehicle: A vehicle provided to an individual or an organizational element of a government agency by GSA's Interagency Fleet Management System for short term use, usually on a day to day basis, not to exceed 30 consecutive days. (GSA1)

Displaced Threshold: A threshold located at a point on the runway other than at the beginning of the usable runway pavement. The displaced area is available for takeoff. (FAA12)

Displacement: The weight, in tons of 2,240 pounds, of the vessel and its contents. Calculated by dividing the volume of water displaced in cubic feet by 35, the average density of sea water. (MARAD2)

Disposable Income: Personal income less personal tax and non-tax payments. (DOE6)

Disposal Date: The date a vehicle is disposed of and no longer included in the inventory. (GSA2)

Disposal Storage: An inventory accountability category of vehicles not in use and scheduled for disposal. (GSA2)

Disposal Storage Date: The date a vehicle is taken out of service and placed in disposal storage. (GSA2)

Disqualification: 1) The suspension, revocation, cancellation, or any other withdrawal by a State of a person's privileges to drive a commercial motor vehicle or 2) A determination by the Federal Highway Administration (FHWA), under the rules of practice for motor carrier safety contained in 49 CFR 386, that a person is no longer qualified to operate a commercial motor vehicle under 49 CFR 391; or 3) The loss of qualification which automatically follows conviction of an offense listed in 49 CFR 383.51. (49CFR383)

Distance Measuring Equipment (DME): Airborne and ground equipment used to measure, in nautical miles, the slant range distance of an aircraft from the Distance Measuring Equipment (DME) navigational aid. (FAA4) (FAA6)

Distance Measuring Equipment (DME) Fix: A geographical position determined by reference to a navigational aid which provides distance and azimuth information. It is defined by a specific distance in nautical miles and a radial, azimuth, or course (i.e., localizer) in degrees magnetic from that aid. (FAA4)

Distance Measuring Equipment (DME) Separation: Spacing of aircraft in terms of distances (nautical miles) determined by reference to distance measuring equipment. (FAA4)

Distillate Fuel Oil: A general classification for one of the petroleum fractions produced in conventional distillation operations. It is used primarily for space heating, on and off highway diesel engine fuel (including railroad engine fuel and fuel for agricultural machinery), and electric power generation. Included are products known as No. 1, No. 2, and No. 4 fuel oils and No. 1, No. 2, and No. 4 diesel fuels. No. 1 distillate is a petroleum distillate which meets the specifications for No. 1 heating or fuel oil as defined in American Society for Testing and Materials (ASTM) D 396 and/or the specifications for No. 1 diesel fuel as defined in ASTM Specification D 975. No. 2 Distillate is a petroleum distillate which meets the specifications for No. 2 heating oil or fuel oil as defined in ASTM D 396 and/or the specifications for No. 2 diesel fuel as defined in ASTM Specification D 975. (DOE2) (DOE3)

Distress: A condition of being threatened by serious and/or imminent danger and of requiring immediate assistance. (FAA4)

Distress: The state of being in peril, to any degree, for a person and/or property. (USCG3)

Distressed Unit: A person and/or property in peril to any degree. (USCG3)

Distributary: A branch of a river that flows away from the main stream and does not return to it. (TNDOT1)

Distribution Main: Generally, mains, services, and equipment that carry or control the supply of gas from the point of local supply to and including the sales meters. (AGA1)

Distributor: A company primarily engaged in the sale and delivery of natural and/or supplemental gas directly to consumers through a system of mains. (DOE5)

District Commander: The District Commander of the Coast Guard or his authorized representative, who has jurisdiction in the particular geographical area. (49CFR171)

Ditch Light: Spotlight aimed at right side of road. (ATA1)

Diverse Vector Area: In a radar environment, that area in which a prescribed departure route is not required as the only suitable route to avoid obstacles. The area in which random radar vectors below the Minimum Vectoring Altitude/Minimum Instrument Flight Rules Altitude (MVA/MIA), established in accordance with the Terminal Instrument Procedures criteria for diverse departures obstacles and terrain avoidance, may be issued to departing aircraft. (FAA4)

Divided Highway: A multi-lane facility with a curbed or positive barrier median, or a median that is 4 feet (1.2 meters) or wider. (FHWA2)

Division: An established point where driver ends trip. (ATA1)

Dl: Deciliter (NHTSA3)

DLG: Digital Line Graphs (BTS2)

DLP: Data-Link Processor (FAA17) (FAA19)

DMC: Defense Movement Coordinator (MTMC1)

DME: Distance Measuring Equipment (FAA4) (FAA17) (FAA6) (FAA7) (FAA8)

DME/P: Precision Distance Measuring Equipment (FAA17) (FAA19)

DMN: Data Multiplexing Network (FAA19)

Dock: (See also Marina, Pier, Wharf) For ships, a cargo handling area parallel to the shoreline; for land transportation, a loading or unloading platform at an industrial location or carrier terminal. (MARAD2)

Dock It: Park truck at dock. (ATA1)

Dock Receipt: Written acknowledgment showing that goods have been delivered and received at dock or warehouse of ocean liner. (TNDOT1)

Dock Receipt: A receipt used to transfer accountability when the export item is moved by the domestic carrier to the port of embarkation and left with the international carrier for export. (USTTA1)

Dock Walloper: One who loads and unloads vehicles and handles freight on the dock. (ATA1)

Dockage: (See also Wharfage) Charge assessed against a vessel for berthing at a wharf, pier, bulkhead structure, or bank or for mooring to a vessel so berthed. (MARAD1)

Documented Yacht: A vessel of five or more net tons owned by a citizen of the United States and used exclusively for pleasure with a valid marine document issued by the Coast Guard. Documented vessels are not numbered. (USCG2)

Documents Against Acceptance: Instructions given by a shipper to a bank indicating that documents transferring title to goods should be delivered to the buyer (or drawee) only upon the buyer's payment of the attached draft. (USTTA1)

DOD: Department of Defense (BTS8) (FAA17) (FAA19)

DODX: Department of Defense-Owned Rail Cars (MTMC1)

DOE: Department of Energy (BTS2) (DOE3)

Dog: Truck with little power. (ATA1)

Dog Chart: (See also Locking Dog) [with respect to rail operations] A diagrammatic representation of the mechanical locking of an interlocking machine, used as a working plan in making up, assembling and fitting the locking. (49CFR236)

Dog Tracks: Unit or straight truck that runs out of line. (ATA1)

DOI: Department of Interior (RSPA1)

Dolly: An auxiliary axle assembly having a fifth wheel used for purpose of converting a semitrailer to a full trailer. (ATA2)

Dolphin: (See also Mooring Cell) An isolated cluster of piles used as a support for mooring devices or marker lights. (TNDOT1)

DOM ICE: Domestic Icebreaking (USCG5)

Domestic: Produced in the United States, including the Outer Continental Shelf (OCS). (DOE5)

Domestic: Traffic (passengers and freight) performed between airports located within the same country or territory. (ACI1)

Domestic Air Defense Identification Zone: An Air Defense Identification Zone (ADIZ) within the United States along an international boundary of the United States. (FAA4)

Domestic Air Operator: Commercial air transportation within and between the 50 States and the District of Columbia. Includes operations of certificated route air carriers, Pan American, local service, helicopter, intra-Alaska, intra-Hawaii, all-cargo carriers and other carriers. Also included are transborder operations conducted on the domestic route segments of U.S. air carriers. Domestic operators are classified based on their operating revenue as follows: Major (over $1 billion); National ($100-1,000 million); Large Regional ($10-99.9 million); Medium Regional ($0-9.99 million). (DOE6)

Domestic Airspace: Airspace which overlies the continental land mass of the United States plus Hawaii and U.S. possessions. Domestic airspace extends to 12 miles offshore. (FAA4)

Domestic Fleet: All reportable agency owned motor vehicles, operated in any State, Commonwealth, Territory or possession of the United States. (GSA1)

Domestic Freight: All waterborne commercial movements between points in the United States, Puerto Rico, and the Virgin Islands, excluding traffic with the Panama Canal Zone. Cargo moved for the military in commercial vessels is reported as ordinary commercial cargo; military cargo moved in military vessels is omitted. (TNDOT1)

Domestic Intercity Trucking: Trucking operations within the territory of the United States, including intra-Hawaiian and intra-Alaskan, which carry freight beyond the local areas and commercial zones. (ATA2)

Domestic Operation: In general, operations within and between the 50 States of the United States, the District of Columbia, American Samoa, Caroline Islands. Guam Island, Johnston Island, Marianna Islands, Midway Island, Puerto Rico, U.S. Virgin Islands and Wake Island. (FAA15)

Domestic Operations: All air carrier operations having destinations within the 50 United States, the District of Columbia, Puerto Rico, and the U.S. Virgin Islands. (DOE5) (FAA14)

Domestic Passenger: Any person traveling on a public conveyance by water between points in the United States, Puerto Rico, and the Virgin Islands. (TNDOT1)

Domestic Transportation: Transportation between places within the United States other than through a foreign country. (49CFR171)

Donut Area: The area outside of the Federal Highway Administration (FHWA) approved adjusted boundary of one or more urbanized areas but within the boundary of a National Ambient Air Quality Standards (NAAQ) non-attainment area. (FHWA2)

Donuts: Truck tires. (ATA1)

Doodle Bug: Small tractor used to pull two axle dollies in a warehouse. (ATA1)

Door Sill Step: Any step normally protected from the elements by the cab door when closed. (49CFR399)

DOT: Department of Transportation (BTS2) (FAA3) (FAA19) (FHWA7) (MTMC1)

DOTS: Dynamic Ocean Tracking System (FAA17) (FAA19)

Double: (See also Rocky Mountain Double; Turnpike Double) A combination of two trailers pulled by a power unit. Usually refers to a power unit pulling two 28 foot trailers. (ATA2)

Double: The maneuver whereby a towboat with barges in tow must break the tow and push half of it into the lock chamber, lock that part through, and then enter the remaining barges with the towboat. In other words, two distinct lockage must be made to pass the entire tow of barges and towboat. Also called "double lockage." (TNDOT1)

Double Bottom: Unit consisting of tractor, semitrailer and full trailer. Also called "twin trailers", "doubles." (ATA1)

Double Clutching: Shifting the gears of a truck transmission without clashing them. (ATA1)

Double Deck Bus: A bus with two separate passenger compartments, one above the other. (APTA1)

Double Decked Buses: High-capacity buses having two levels of seating, one over the other, connected by one or more stairways. Total bus height is usually 13 to 14.5 feet, and typical passenger seating capacity ranges from 40 to 80 people. (FTA1)

Double Heading Cock: A manually operated valve by means of which the control of brake operation is transferred to the leading locomotive. (49CFR236)

Double Lockage: See Double.

Double Trip: The maneuver necessary when a towboat has more barges in tow than the power of the boat can handle in certain areas of swift current or conditions at the lock will permit. A tow will tie off below the swift water a portion of his tow, push the others above the questionable area, tie them off to the bank, and go back for the remainder of the tow. This is also a necessary maneuver in ice at times. (TNDOT1)

Down Draft: The natural tendency for the river current to pull objects downstream. (TNDOT1)

Down In the Corner: "Creeper" gear. (ATA1)

Down Shape of (Revetment, Shore, Etc.): Running the shape of the shore, staying approximately the same distance off the shore at all times. (TNDOT1)

Downtime: The amount of time a vehicle or equipment is out of service for repair. (GSA2)

Downtown People Mover: A type of automated guideway transit vehicle operating on a loop or shuttle route within the central business district of a city. (APTA1)

DPM: Downtown People Mover (TRB1)

Draft: 1) Crosscurrent; tows will drift to the right or left depending on the draft (usually qualified as out draft, or left-or right-handed draft). 2) The depth of water a vessel draws, loaded or unloaded. (TNDOT1)

Drag Down: Shift too slowly to lower gears. (ATA1)

Drainage Basin: The land drained by a river system. (DOE5)

Draw Back: Repayment in whole or in part of duties or taxes paid on imported merchandise that is re-exported. (TNDOT1)

Draw Down: The procedure of spilling water through one dam prior to the arrival of excessive water from the upper reaches of the river. This maneuver is used when flash floods are expected or have occurred or where tributary streams are emptying excessive amounts of water into the main streams. (DOE5) (TNDOT1)

Draw Span: The movable portion of a bridge deck. (DOI3)

Drawbridge: A bridge that pivots or lifts so as to let a boat through. (TNDOT1)

Drayage: Charge made for local hauling by dray or truck. (MARAD2)

Dredge Material: Material that is excavated or dredged from waters of the United States. (TNDOT1)

Dredged Cut: 1) One pass made by a dredge in a channel within the confines of the riverbed for the purpose of maintaining the proper depth of water; 2) a dredged channel. (TNDOT1)

Dredged Shipping Lane: Lane that has been dug out to provide an adequate depth of water for navigation. (DOI3)

Dredging: To clean, deepen or widen with a machine equipped with scooping or suction devices used in deepening harbors and waterways and in underwater mining. (BOC2)

Dredging Spoil: The discharge from a dredge. (TNDOT1)

DRFS: Destination Rail Station (MARAD2)

Drift: 1) The motion of a boat floating with no mechanical aid. 2) Debris floating in the river or lodged along shore in a drift pile. 3) Colloquially used as a synonym for currents: "how does the drift set around this bridge pier?" Also referred to as "Current", "Set", or "Draft". (TNDOT1)

Drifting: Underway, but proceeding over the bottom without use of engines, oars or sails; being carried along only by the tide, current, or wind. (USCG2)

Drive: To use full power ahead. Also called Punch. (TNDOT1)

DRIVE: Dedicated Road Infrastructure for Vehicle Safety in Europe (FHWA15)

Drive Her Through: To proceed full speed ahead. (TNDOT1)

Driveaway-Towaway: Refers to a carrier operation, such as a fleet of tow trucks, used to transport other vehicles, when some or all wheels of the vehicles being transported touch the road surface. (FHWA4)

Driveaway-Towaway Operation: Any operation in which a motor vehicle constitutes the commodity being transported and one or more set of wheels of the vehicle being transported are on the surface of the roadway during transportation. (49CFR390)

Driver: See also Operator.

Driver: 1) A person who operates a motorized vehicle. If more than one person drives on a single trip, the person who drives the most miles is classified as the principal driver. 2) An occupant of a vehicle who is in physical control of a motor vehicle in transport or, for an out of-control vehicle, an occupant who was in control until control was lost. (FHWA3) (NHTSA3)

Driver Applicant: An individual who applies to a State to obtain, transfer, upgrade, or renew a commercial driver's license (CDL). (49CFR383)

Driver's License: A license issued by a State or other jurisdiction, to an individual which authorizes the individual to operate a motor vehicle on the highways. (49CFR383)

Drivers: Drive wheels. (ATA1)

Driving a Commercial Motor Vehicle While Under the Influence of Alcohol: Committing any one or more of the following acts in a commercial motor vehicle (CMV): driving a CMV while the person's alcohol concentration is 0.04 percent or more; driving under the influence of alcohol, as prescribed by State law; or refusal to undergo such testing as is required by any State or jurisdiction in the enforcement of 49 CFR 383.51b)2)(i)a) or b), or 49 CFR 392.5a)2). (49CFR383) (49CFR390)

Driving Piece: A crank secured to a locking shaft by means of which horizontal movement is imparted to a longitudinal locking bar. (49CFR236)

Driving Under the Influence (DUI): The driving or operating of any vehicle or common carrier while drunk or under the influence of liquor or narcotics. (FTA1)

DRL: Daytime Running Lights (NHTSA5)

Drop It On the Nose: Uncoupling a tractor from a semitrailer without lowering the landing gear to support the trailer's front end. (ATA1)

Drop the Body: Unhook and drive a tractor away from a parked semi. (ATA1)

Dropping Out Line: A line used in dropping a barge out of a tow. (TNDOT1)

Drum: A flat-ended or convex-ended cylindrical packaging made of metal, fiberboard, plastic, plywood, or other suitable materials. This definition also includes packagings of other shapes made of metal or plastic (e.g., round taper-necked packagings or pail-shaped packagings) but does not include cylinders, jerricans, wooden barrels or bulk packagings. (49CFR171)

Dry Bulk Cargo: Cargo which may be loose, granular, free-flowing or solid, such as grain, coal, and ore, and is shipped in bulk rather than in package form. Dry bulk cargo is usually handled by specialized mechanical handling equipment at specially designed dry bulk terminals. (MARAD1)

Dry Cargo: Cargo that does not require temperature control. (MARAD2)

Dry Gas: Natural gas from which the entrained liquids and nonhydrocarbon gases have been removed by lease facilities and/or plant processing. This is the gas that the interstate pipeline purchased, or expects to purchase, to serve its annual requirements. (DOE5)

Dry Hole: An exploratory or development well found to be incapable of producing either oil or gas in sufficient quantities to justify completion as an oil or gas well. (DOE5)

Dry-Bulk Container: A container constructed to carry grain, powder and other free-flowing solids in bulk. Used in conjunction with a tilt chassis or platform. (MARAD2)

Drydock: An artificial basin fitted with gate or caisson into which a vessel may be floated and from which the water may be pumped out to expose the bottom of the vessel. (DOI4)

Drydock Gate: Gate at the entrance to a drydock. (DOI3)

DSB: Double Sideband (FAA19)

DSEDM: Departure Sequencing Engineering Development Model (FAA7)

DSM: Des Moines International Airport (FAA11)

DSP: Departure Sequencing Program (FAA4) (FAA17) (FAA19)

DSR: Display System Replacement (FAA19)

DSS: Decision Support System (USCG5)

DSUA: Dynamic Special - Use Airspace (FAA17)

DT: Delay Time (FAA4)

DTDM: Deterministic Time Division Multiplexing (FAA19)

DTO: Division Transportation Officer (MTMC1)

DTPC: Defense Transportation Policy Council (MTMC1)

DTS: Defense Transportation System (MARAD4) (MTMC1)

DTW: Detroit Metropolitan Wayne County Airport (FAA11)

Dual Drive: (See also Tandem) Box axles have drive mechanisms and are connected to engine power output. 1) pusher tandem: only the rearmost axle is driving type and the forward unit is free rolling, also called "dead axle"; 2) tag axle: forward unit of tandem is driving type while rear unit is free rolling. (TII1) (TII2)

Duals: A pair of tires mounted together. (ATA1)

DUATS: Direct User Access Terminal System (FAA14)

Duck Water: Slack water. Smooth water generally found on the inside shore of a river bend, under a point, under a bar, etc. (TNDOT1)

DUI: Driving Under the Influence (NHTSA6)

Dumb Barge: Slang term for a barge that does not have its own power. (TNDOT1)

Dump Body: Truck body of any type which can be tilted to discharge its load. (ATA1)

Dusting: Driving with wheels on road shoulder, thereby causing a cloud of dust. (ATA1)

Duty: A tax imposed by a government on imports. (TNDOT1)

DVA: Diverse Vector Area (FAA4)

DVFR: Day Visual Flight Rules (FAA6) (FAA13)

DVFR: Defense Visual Flight Rules (FAA2) (FAA4) (FAA6)

DVIR: Driver Vehicle Inspection Report (FHWA10)

DVMT: Daily Vehicle-Miles of Travel (FHWA12) (FHWA8)

DVOR: Doppler Very High Frequency Omnidirectional Range (FAA17) (FAA19)

DWI: Driving While Intoxicated (NHTSA6)

DWT: Deadweight Tons (MARAD4)

Dynamic Routing: In demand-response transportation systems, the process of constantly modifying vehicle routes to accommodate service requests received after the vehicle began operations, as distinguished from predetermined routes assigned to a vehicle. (TRB1)

Dynamite the Brakes: Emergency stop using every brake on the unit. (ATA1)

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