Transportation Glossary

The following is a listing of transportation-related terminology and phraseology developed by CCMPO.
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Term	Acronym	Definition
Tax Increment Finance District	TIF	Locally designated area receiving targeted investments from increased property tax revenue.
Technical Assistance	TA	The CCMPO technical assistance program provides technical support relating to transportation issues for member municipalities and agencies. Services typically provided through this program include: Traffic Counts, Speed Limit Recommendations, Traffic Signal Optimization, Traffic Control Warrant Analysis, Roadway Surface Management Studies, Small Area Transportation Studies, and Safety Studies.
Telecommunications Display Device	TDD	Apparatus that converts telephoned information to visual form on a computer screen. Useful to hearing or speech-impaired individuals.
Telecommuting		Telecommuting or telework enable potential commuters to work outside the traditional office or workplace, usually at home or in a mobile situation, communicating electronically (by telephone, internet, or teleconference, etc.) with an office from home instead of traveling to it physically.
Throughput		Total amount of freight imported or exported via a freight facility measured in TEUs or tons over a given period of time.
Ton-Mile		The movement of 1 ton of cargo the distance of 1 mile. Ton-miles are calculated by multiplying the weight in tons of each shipment transported by the miles hauled.
Traffic Analysis Zone	TAZ	Chittenden County is divided into 335 small areas. Each area has relatively similar characteristics within its boundaries. Often derived from Census Blocks, or Block Groups, TAZs represent land use data on housing and employment in the Travel Demand modeling process.
Traffic Assignment		In the four step practice of Travel Demand Modeling, Traffic Assignment is the process of predicting the specific path travelers take from their Origin to their Destination.
Traffic Calming		The use of education, enforcement, and engineering to change the behavior of drivers and increase safety.
Traffic Circle		Traffic circles (or rotaries) are intersections designed for high speed entry and multi-lane maneuvering. Historically, many have given driver Right-of-Way to entering vehicles, causing gridlock and traffic congestion. Because traffic circles suffered high crash rates and operational problems, they fell out of favor in the US during the 1950s and 1960s. Traffic circles are NOT Roundabouts.
Traffic Impact Study	TIS	Also known as Traffic Impact Analysis (TIA), these are studies which collect and analyze information to determine need, impact, and impact mitigation for major roadway improvements. Some activities of a TIS include; Traffic counts, Crash evaluation, Capacity & Level Of Service calculation, Signal Warrant analysis, Development of condition diagrams, Forecasting future traffic volumes with new development and/or alternatives.
Trailblazers		Directional signs placed at strategic locations along high-volume roads, indicating direction to convenient routes or points of access to facilities.
Trailer-on-Flatcar	TOFC	A shipping container capable of transport upon a rail flat car or truck flat bed trailer. Same as COFC.
Train-Mile		The movement of a train, which can consist of many cars, the distance of one mile. A train-mile differs from a vehicle-mile, which is the movement of one car (vehicle) the distance of one mile. A 10-car (vehicle) train traveling 1 mile is measured as 1 train-mile and 10 vehicle-miles. Caution should be used when comparing train-miles to vehicle-miles.
TransCAD		A computer software “platform” used for the CCMPO transportation model.
Transit		Generally refers to urban passenger transportation service, (private or public) along established routes with fixed or variable schedules at published fares.
Transit Options		Infrastructural refinements which assist commuters with intermodal intermodal transitions. Examples of Transit Options are; Trail connection to bus, rail or ferry station, Bike racks on buses, Bike parking/rental/sharing at transit stations, Improved pedestrian access to transit, Long-term bike storage at Park & Rides or transit centers, et al.
Transit-Oriented Design	TOD	High density and mixed use land development around transit system stops.
Transit-Oriented Development	TOD	Mixed-use (residential, commercial, and industrial) development and zoning designed around commuter rail or bus facilities and infrastructure.
Transit-Ready Development	TRD	Similar to TOD, TRD prepares a neighbourhood, corridor, or area for future transit expansion with neighbourhood densities, road networks, pedestrian infrastructure, and public facilities designed as transit destinations.
Transload		Transload facilities provide shippers/receivers with access to rail transportation and storage capacities that otherwise would be unavailable. This enables a local business to purchase a rail car load of product at a lower price per unit, and provides opportunities for several shippers/receivers to consolidate their freight to take advantage of the economies offered by rail. This translates into lower costs and reduced dependence on trucks. Facility features may include; cranes, forklifts, undertrack unloading equipment, conveyors, truck and rail car scales, and rail moving equipment to expedite placement of rail cars for loading and unloading.
Transportation Action Grant	TAG	A CCMPO sponsored competitive planning grant program designed to encourage innovative, action-oriented transportation planning initiatives in Chittenden County.
Transportation Advisory Committee	TAC	A committee that recommends plans and programs to the CCMPO Board (formerly know as the Technical Advisory Committee).
Transportation Capital Program		The annual program devised by the State of Vermont to determine and prioritize transportation capital investments statewide. These needs and cost estimates are updated annually in the program. This process is coordinated with the CCMPO through the TIP development process.
Transportation Control Measures	TCM	Actions, which are usually found in a State Implementation Plan (SIP), that improves traffic flow, reduce vehicle use, or decrease congestion with the objective of lessening air pollutant emissions.
Transportation Demand Management	TDM	Low-cost programs that focus on decreasing travel and the use of SOVs, and increasing the use of other modes.
Transportation Enhancement Program	TE	Federal funding program for projects designed to enhance transportation related quality of life. Such projects and programs generally relate to such activities as; Bicycle and pedestrian infrastructure and safety programs, Scenic and historic highway programs, Landscaping and scenic beautification, Historic preservation, and Environmental mitigation.
Transportation Equity Act for the 21st Century	TEA-21	Enacted in July 1998, TEA-21 calls for integrating all modes of transportation - cars, trains, trucks, buses, ferries, walking and biking - into a single, efficient and 'seamless' transportation system. It mandates greater local control over transportation funding decisions through MPOs, such as the CCMPO.
Transportation Improvement Program	TIP	A list of federally funded projects planned for a four-year period and consistent with the goals of the MTP.
Transportation Management Area	TMA	An area designated by the US Secretary of Transportation, having an urbanized area population of over 200,000, or upon special request from the Governor and the MPO, or under special circumstances designated for the area.
Transportation Management Association	TMA	A voluntary association of public organizations, private agencies, and businesses joined to develop cooperative transportation programs in a given area.
Transportation Planning Initiative	TPI	An effort by VTrans to ensure that the public plays a significant role in determining which transportation problems to be addressed and the scale of those improvements.
Transportation Research Board	TRB	TRB is one of six major divisions of the National Research Council, advising the President and Congress specifically on the development of transportation. TRB is a forum engaging engineers, scientists, and other transportation researchers and practitioners from the public, private, and academic sectors to promote progress and innovation through interdisciplinary research.
Transportation Systems Management	TSM	Low-cost projects that focus on how the transportation system responds to people’s needs. Most examples are in intersection and signal improvements, such as; signal timing optimization, controller/cabinet and signal head upgrades, vehicle detectors repair/replacement, turning lanes, grade separations, pavement striping, lane assignment changes, signage and lighting.
Transportation for Livable Communities	TLC	A CCMPO grant program that supports development that strengthens the link between transportation investments and community livability.
Transportation, Community and System Preservation Program	TCSP	Federal program that provides funding for planning grants, implementation grants, and research to investigate and address the relationships between transportation, community and system preservation.
Travel Demand Forecasting (Modelling)	TDF	A four-step (some consider it a five-step) process used to predict future traffic on a transportation network. The five steps, in order, are; 1. Trip Generation, 2. Trip Distribution, 3. Mode Split/Mode Choice, 4. Traffic Assignment, and 5. Model Validation and Reasonableness Checks.
Trigger		The value of a measurable indicator (e.g. average daily traffic, volume-to-capacity ratio, population density) that, when reached, will cause a set of agreed-upon actions to be taken (e.g. conduct traffic study).
Trip Attraction		The process of attracting trips to a zone. It is generally a function of the land uses in a zone.
Trip Distribution		The process of determining trip exchanges; the number of trips between each pair of zones.
Trip Generation		The first step in the four-step Travel Demand Modeling process, which estimates the number and types of trips types taken by travelers (e.g. Home-To-Work, Nonwork-To-Home, etc.).
Trip Generation Manual		Published by the Institute of Transportation Engineers (ITE), the Trip Generation Manual is intended to advise planners and engineers on trip generation rates based on land use category, building type, and other site plan related information. Trip generation rates have been developed from compiled traffic data collected from thousands of traffic studies. The Vermont Agency of Transportation (VTrans) released its own version of the Trip Generation Manual in 2010 in answer to the challenge that ITE trip generation rates are not representative of small urban and rural areas in Vermont.
Trip Reduction Ordinance	TRO	Local regulations requiring employers, developers, or housing managers to provide incentives for workers or residents to use alternative modes of transport.
Truck Apron		Component of a roundabout central island, which accommodates the "Offtracking" of large trucks or buses, but is not intended to be driven by automobiles. Truck aprons generally are a raised and widened concrete or brick pad constructed along the perimeter of the central island.
Truck Load	TL	"Truckload", or "Full Truckload" carriers (FTL or TL) usually haul freight in single moves from shipper to receiver (See FTL for a more detailed description).
Truck Network		Road network designated for freight truck travel. The national network has no overall vehicle length limits, nor permit requirements (e.g. I-9, I-89, I-189, and parts of US 7 & US 4). The Vermont network requires permits for any vehicles longer than 72'. The remainder of state highways (not on the truck network) require a permit for trucks and have a 68' vehicle length limit.
Truss		A framed structure of a bridge, comprised of a series of triangles or other stable shapes (made from a network of connected beams). A "plane truss" example is where all members and joints lie within a 2-dimensional plane, while a "space truss" has members and joints extending into 3 dimensions.
Twenty-Foot Equivalent Unit	TEU	A Twenty-Foot Equivalent Unit is used to express shipping or capacity volume of freight. Using the ISO standard of a 20-foot shipping container as a means of measurement, TEUs further summarise a general sense of freight traffic moving through major shipping ports commonly reported by government or industry. A TEU is an approximate measure of containerized cargo capacity (20 ft. long * 8 ft. wide container), which does not account for container height.
Typical Day		A weekday exhibiting travel patterns which occur on a regular basis. Generally, there is standard practice for collecting traffic-related data on Mondays through Thursdays of weeks without holidays or other occurrences that arguably influence travel patterns.

OTHER TRANSPORT TERMINOLOGY REFERENCES: