Transportation Glossary

The following is a listing of transportation-related terminology and phraseology developed by CCMPO.
Click here to view a list of Acronyms only...

ALL < A B C D E F G H I J K L M N O P Q R S T U V W X Y Z > NUMERIC

Term	Acronym	Definition
I-95 Corridor Coalition		The I-95 Corridor Coalition is an alliance of transportation agencies, toll authorities, and related organizations, including public safety, from the State of Maine to the State of Florida, with affiliate members in Canada. The Coalition provides a forum for key decision and policy makers to address transportation management and operations issues of common interest. This volunteer, consensus-driven organization enables its myriad state, local and regional member agencies to work together to improve transportation system performance far more than they could working individually. The Coalition has successfully served as a model for multi-state/jurisdictional interagency cooperation and coordination for over a decade. Vermont is considered to be a part of the I-95 region.
Impact Fee		A local government imposed fee upon developers, which in theory is used to finance infrastructure costs and improvements that handle increased service caused by new development.
Indirect Impacts		Impacts that are caused by an action (such as a transportation project) that occur later in time and farther removed in distance, but are still foreseeable. Also known as "Secondary Impacts."
Induced Travel		Formally known as the "Traffic Inducement Effect", it is a highly debated concept in transportation planning, which postulates that improvements intended to increase highway capacity are only a temporary solution. Simply stated, Induced Travel is any increase in daily travel (measured as Passenger Miles of Travel [PMT] or Vehicle Miles of Travel [VMT]) resulting from a change in the transportation system.
Ingress		A way of entering or travelling to a location. Ingress generally describes vehicle or pedestrian movements from the perspective of driveways and walkways which provide "ingress to a property", or more commonly "Ingress & Egress to a property" or "Access & Egress to a property".
Innovative Finance	IF	A broadly defined term that encompasses a combination of specially designed techniques to supplement traditional federal financing methods for transportation-related projects. Often in the form of "Public-Private Partnerships", locally authorized "Tax-Increment Financing", et al., Innovative Finance for transportation seeks to; 1. Maximize the ability of states and other project sponsors to leverage Federal capital for needed investment in the nation's transportation system; 2. More effectively utilize existing funds; 3. Move projects into construction more quickly than under traditional financing mechanisms; and 4. Make possible major transportation investments that might not otherwise receive financing.
Inscribed Circle Diameter	ICD	Diameter of a Rotary, Roundabout, or Circulator intersection. Generally speaking, a smaller ICD of a modern roundabout keeps the traffic speed lower, and hence safer than the larger ICD's commonly found with rotaries or traffic circles.
Intelligent Transportation Systems	ITS	Technology used to improve the efficiency of transportation systems.
Intercept Facility		Otherwise known as a "Satellite Facility", an Intercept "Park & Ride" facility's purpose is to provide a less expensive parking alternative to on-site locations within activity centers or the urban core area and reduce SOV use in activity centers. These facilities may capture outgoing as well as incoming activity center traffic and serve as a transfer point from car to shuttle or transit. Characteristics include an urban/activity area fringe location, high capacity, surface or structured parking, and high frequency shuttle/transit connections to activity centers. Implementation funding is likely to come from Congressional earmarks and/or public private ventures.
Intermodal		Planning that reflects a focus on connectivity between modes and emphasizes choices, coordination, and cooperation.
Intermodal Surface Transportation Efficiency Act of 1991	ISTEA	The purpose of this act was to develop a 'National Intermodal Transportation System that is economically efficient, environmentally sound, provides the foundation for the Nation to compete in the global economy and will move people and goods in an energy efficient manner.' This act established the provision that MPO's undertake development of a Transportation Improvement Program (TIP), a long-range plan, and an annual work program. It also required for states; a statewide planning process, a statewide transportation plan, and a statewide transportation improvement program (STIP).
Intermodal Transfer Facility		Involves moving containers between rail and truck, or other modal combinations, and can increase efficient transportation services and energy efficiency because a train loaded with containers can carry the same load as dozens of trucks. Such service can contribute to reduced truck traffic on congested highways, reduced damage to highways from heavy trucks, and improved air quality.
International Organization for Standardization	ISO	Based in Geneva, Switzerland, ISO is a non-governmental organization (NGO) coordinating the publication and development of a host of International Standards for government, private-sectors. Such standards apply to equipment specifications, data transfer standards, monitoring standards, et al. The acronym "ISO" is derived from the Greek 'isos' (meaning "equal"). Hence "ISO" is applicable to any country or language as a mark of an international standard.
International Roughness Index	IRI	A pavement condition profiling indicator (used by HPMS, et al.) reflecting ride smoothness. IRI data is captured by a device mounted on a vehicle measuring suspension motion per distance travelled, and may be expressed in inches/mile (in/mi) or meters/kilometer (m/km). An IRI of 0m/km means that a roadway is perfectly smooth. And where there is no maximum for this indicator, it is generally accepted that an IRI of 8m/km is almost impassible unless vehicle speeds are greatly reduced.
Intersection Sight Distance	ISD	The AASHTO "Green Book" reference to the "Line of Sight" distance between a vehicle travelling on a roadway and a vehicle attempting to enter the roadway from an intersection or driveway.
Interstate Highway System	IHS	A subsystem of the NHS, the Interstate Highway System is also named the "Dwight D. Eisenhower National System of Interstate and Defense Highways". The concept of the IHS was first formally studied under mandate by the Federal-Aid Highway Act of 1938, and was first authorized construction funds under the Federal-Aid Highway Act of 1952. It was not until the enactment of the Federal-Aid Highway Act of 1956, championed by President Eisenhower, that the Highway Trust Fund was established to finance construction of the entire network for the purpose of facilitating private and commercial transportation, and providing transportation routes for military supplies and troop deployments in case of an emergency or foreign invasion.
Interstate Maintenance Program		Federal program providing funding for resurfacing, restoring, rehabilitating and reconstructing (4R) most routes on the Interstate Highway System.

OTHER TRANSPORT TERMINOLOGY REFERENCES: