Growth Management- A longer-term tool for action against traffic problems through comprehensive
land-use planning and policies.
GSM– Global System for Mobile Communications
HAR-- Highway Advisory Radio
HCM– Highway Capacity Manual
HCS– Highway Capacity Software
Headway- Time interval between vehicles moving in the same direction on a particular route.
Heavy Rail- See "Rail, Heavy".
High Speed Rail- See "Rail, High Speed".
Highway- A rural and suburban thoroughfare of high vehicular speed and capacity. This type is allocated
to the more rural transect zones (T1, T2, and T3).
Highway Trust Fund- The federal trust fund established by the Highway Revenue Act of 1956; this fund
has two accounts — the Highway Account and the Mass Transit Account. Trust fund revenues are
derived from federal highway-user taxes and fees such as motor fuel taxes; trust fund uses and
expenditures are determined by law.
Horizontal Alignment- The horizontal alignment of a highway, railway, or transit guideway represents
the projection of the facility on a horizontal plane.
High Occupancy Toll Lane (HOT Lane)- A lane of freeway reserved for the use of vehicles with more than
one passenger, including buses, taxis, carpools, motorcycles, electric vehicles, as well as single-occupant
vehicles that pay a predetermined toll.
HOV - High-Occupancy-Vehicle Lane- The technical term for a carpool lane, commuter lane or diamond
lane.
Impact Fee- A cost imposed on new development to fund public facility improvements required by new
development and ease fiscal burdens on localities.
Infrastructure- The basic facilities, such as roads, public buildings (schools, libraries, fire stations),
utilities (water, sewer, electric, gas), and communications systems on which the continuance and growth
of a community depends. Infrastructure is needed to sustain industrial residential, commercial, and all
other land use activities.
ICC – Intelligent Cruise Control- (See AVCS)
Incident Management- Systematical monitoring of traffic flow on transportation systems that provides
useful information for identifying and responding to traffic incidents.
IS - Initial Study- A preliminary analysis prepared by the Lead Agency to determine whether an EIR or a
Negative Declaration must be prepared, or to identify the significant environmental effects to be
analyzed in an EIR. Use of the Initial Study is discussed in Article 5, commencing with Section 15060 of
the California Code.
Intermodal- Those issues or activities which involve or affect more than one mode of transportation
including transportation connections, choices, cooperation, and coordination of various modes. Also
known as "multimodal." The term "mode" is used to refer to and to distinguish from each other the
various forms of transportation such as automobile, transit, ship, bicycle, and walking. Intermodal refers
specifically to the connections between modes, whereas multimodal may refer to a system or corridor
that supports various travel modes.
Intermodal facility- This type of facility is designed for more than one type of
transportation, such as the
loading and unloading of containers from trucks to trains, and from trains to trucks.
ISTEA - Intermodal Surface Transportation Efficiency Act- Pronounced "Ice Tea," this landmark $155
billion federal legislation, signed into law in December 1991, calls for broad changes in the way
transportation decisions are made. ISTEA emphasizes diversity and balance of modes, as well as the
preservation of existing systems before construction of new facilities.
Interregional Transportation Improvements Program (ITIP)- One of the State funding programs also
known as “State Choice.” It is a statewide discretionary program which utilizes 25% of the State
transportation improvement funds and is authorized by the California Transportation Commission (CTC).
Fifteen percent of the funds are used for two programs: 1) Intercity rail (minimum 2.25%); and 2)
Interregional roads outside urban areas (12.75% maximum). Ten percent of the funds are subject to the
California North/South split and can be used in each of those areas as determined by the CTC.
Intersection Capacity Utilization (ICU)- A method for calculating the level of traffic congestion (see Level
of Service) at an intersection.
ITE– Institute of Transportation Engineers
ITS- (1) Intelligent Transportation Systems: The term refers to a wide range of advanced electronics and
communications technology applied to roads and vehicles designed to improve safety and productivity.
(2) Institute of Transportation Studies, University of California. The stated goal of this multicampus
research unit is to "improve the way transportation is organized, managed, and maintained." Projects
cover transportation policy, new technology (see PATH), safety, traffic management, infrastructure, and
freight and logistics.
IVHS - Intelligent Vehicle-Highway System
IVRG – In-vehicle Route Guidance
Jitney- Privately owned, small or medium-sized vehicle usually operated on a fixed route but not on a
fixed schedule.
Joint Development- Ventures undertaken by the public and private sectors for development of land.
Joint ventures are commonly used around transit stations or stops.
Kiss and Ride- A place where commuters are driven and dropped off at a station to board a public
transportation vehicle.
Layover Time- Time built into a schedule between arrival at the end of a route and the departure for the
return trip, used for the recovery of delays and preparation for the return trip.
Lead Agency (CEQA Term)- The public agency which has the principal responsibility for carrying out or
approving a project. The Lead Agency will decide whether an EIR or Negative Declaration will be
required for the project and will cause the document to be prepared. Criteria for determining which
agency will be the Lead Agency per CEQA are contained in Section 15051 of the California Code.
Life-Cycle Maintenance Costs- The concept that transportation infrastructure maintenance occurs
throughout its useful life; for example, a street rebuilt every 15 years will still need regular maintenance
during that time.
Light Rail- See LRT.