Transportation Glossary

The following is a listing of transportation-related terminology and phraseology developed by CCMPO.
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Term	Acronym	Definition
Safe Routes To School	SRTS	Mandated by federal law (SAFETEA-LU), "Safe Routes To School" is intended to benefit children in primary and middle schools (K-8) by encouraging them to walk and bike to school regularly, routinely, and safely. SR2S integrates elements of transportation, economics, health, physical activity, environmental awareness and safety.
Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users	SAFETEA-LU	On 10 August 2005, the new Federal surface transportation act (SAFETEA-LU) was signed into law, authorizing a $286.4 billion transportation program for a 5-year period; FFY 2004-2009. This act covers all surface transportation programs, such as highways, highway safety, transit, freight, and transportation research.
Satellite Facility		Otherwise known as an "Intercept Facility", a Satellite "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.
Scenario Planning		A framework and participatory excercise for developing a shared vision for the future by analyzing various forces (e.g. health, transportation, economic, environmental, land use, etc.) which affect a region's growth. Scenario planning is a collaborative process that tests various future alternatives ability to meet regional and community needs.
Scenic Highway		On the recommendation of the scenery preservation council, the transportation board may designate or discontinue any state highway, or portion of a state highway, as a state scenic road. Such action by the legislative body may be petitioned by the registered voters of a municipality pursuant to the provisions of 24 V.S.A. § 1973.
Scoping		A phase in the project development process that moves a recognized problem from an idea through the development of alternatives and environmental screening (also See "Project Development Process").
Shared Use Path		A path separated from vehicle traffic by barrier or open space usually on its own right-of-way.
Sharrow		Otherwise known as a "Shared-Lane Arrow", sharrows are employed on roadways too narrow for striped bicycle lanes and help to provide guidance to bicyclists and warn motorists about the presence of bicyclists. The sharrow is a printed image of a bike symbol underneath two chevrons upon the roadway.
Short Ton		A measure of weight equalling 2,000 lbs. The Short Ton is distinguished from the Long Ton (or British Ton), which equals 2,240 lbs., as well as the Metric Ton, which equals 2,204.62 lbs.
Signal Optimization Analysis		This analysis maximizes roadway mobility and capacity (without undertaking expensive and inconvenient roadway widening projects) and can help to reduce pollution. More specifically, "Signal Optimization" is the efficient use of a municipality's or corridor's traffic signals by improving their timing parameters (Fixed-Cycle, Offset, and Split parameters) within the controller box located at an intersection to lessen acceleration and idle time of vehicles.
Signal Warrant Analysis		As defined by the Manual on Uniform Traffic Control Devices (MUTCD), a Traffic Signal Warrant Analysis is an engineering study of traffic conditions, pedestrian characteristics, and physical characteristics of the location shall be performed to determine whether installation of a traffic control signal is justified at a particular location.
Single Occupancy Vehicle	SOV	Vehicle carrying only a driver.
Single Point Urban Interchange	SPUI	A variation on a "Diamond Interchange", a SPUI can efficiently move large traffic volumes using a smaller footprint (i.e. less land area) than a standard diamond interchange. SPUI's essentially use a single set of signals to control all through and turning traffic. They are typified by a distinctive ‘hour-glass’ shape, giving the device an efficiency advantage that allows for two simultaneous left-hand turning movements at the signalized intersection.
Small Transit Intensive Cities	STIC	Federal program (or formula) intended to support public transportation in smaller urban areas that have transit systems that perform as well or better than systems in larger metropolitan areas (according to six performance categories; 1. Passenger miles traveled per vehicle revenue mile, 2. Passenger miles traveled per vehicle revenue hour 3. Vehicle revenue miles per capita, 4. Vehicle revenue hours per capita, 5. Passenger miles traveled per capita, and 6.Unlinked passenger trips per capita). Only MPOs with urban-area populations of less than 200,000 are eligible for this funding.
Smart Corridor		An area that uses advanced technology to maintain the flow of multimodal traffic at maximum efficiency.
Smart Growth		Programs and policies designed to maximize preservation of undeveloped land, natural, and cultural resources, whilst economically evolving the established developed communities.
Span		The distance a bridge extends between two supports, or a single piece of support frame, which spans the length of the bridge structure.
Special Services Transportation Agency	SSTA	Chittenden County non-profit organization providing paratransit services.
Special Trip Generators		In modeling context, special generators represent employers (or employer locations) with unique characteristics that are especially large and therefore need to be handled outside of the normal trip generation approach. Examples for the Chittenden County, VT model include; IBM (Essex and Williston), the University of Vermont, and Fletcher Allen Health Care.
Speed Bumps		A Speed Bump is also a raised pavement area across a roadway. Speed bumps are typically found on private roadways and parking lots and do not tend to exhibit consistent design parameters from one installation to another. Speed bumps generally have a height of 3 to 6 inches (76 to 152 mm) with a travel length of 1 to 3 feet (0.3 to 1 m). From an operational standpoint, speed bump impacts within typical residential operational speed ranges slow vehicles to about 5 mph or less at each bump. Speed bumps of varying design have been routinely installed on private roadways and parking lots without the benefit of proper engineering study regarding their design and placement.
Speed Humps		A Speed Hump is a raised area in the roadway pavement surface extending transversely across the travel way. Speed humps are sometimes referred to as "pavement undulations" or "sleeping policemen". Most agencies implement speed humps with a height of 3 to 3.5 inches (76 to 90 mm) and a travel length of 12 to 14 feet (3.7 to 4.3 m). Speed humps are generally used on residential local streets. From an operational standpoint, speed humps impact within typical residential operational speed ranges, slow vehicles to about 20 mph (32 km/h) on streets with properly spaced speed humps. Speed humps have evolved from extensive research and testing and have been designed to achieve a specific result on vehicle operations without imposing unreasonable or unacceptable safety risks.
Speed Tables		Speed Tables are essentially flat-topped speed humps, and may have a textured material on the flat section with asphalt or concrete for the approaches. Speed tables are sometimes referred to as "trapezoidal humps" or "speed platforms". If marked as a pedestrian crossing, speed tables may also be referred to as "raised crosswalks" or "raised crossings". Most agencies implement speed tables with a height of 3 to 3.5 inches (76 to 90 mm) and a travel length of 22 feet (6.7 m). Speed tables generally consist of 10 foot (3.1 m) plateau with 6 foot (1.8 m) approaches on either side that can be straight, parabolic or sinusoidal in profile. The longer lengths of speed tables provide a gentler ride than speed humps and generally result in vehicle operating speeds ranging from 25 to 30 mph (40 to 48 km/h) on streets depending on the spacing between speed tables. Speed tables are generally used on residential collectors, emergency routes or transit routes.
Splitter Islands		A dual-purpose component of a roundabout that serves to deflect traffic speed of entering and exiting vehicles, as well as provide a temporary refuge to pedestrians where crossing is permitted along roadway approaches.
Sprawl		See; "Urban/Sub-Urban Sprawl"
Standard Land Use Coding Manual	SLUCM	Developed by the Housing and Urban Development Agency in 1965, SLUCM was a predecessor to the more current LBCS (APA's Land-Based Classification Standards). The 1965 SLUCM provided a numeric coding schema using two, three, four, or more digits identifying land-use categories. An additional two to eight digits identified Ownership, Type of Structure an activity was housed, and Secondary Use Codes identifying additional land uses. SLUCM land uses categories were derived from Standard Industrial Classification (SIC) codes.
State Implementation Plan	SIP	Clean Air Act plan which identifies how the state will attain and/or maintain NAAQS standards.
State Planning and Research Funds	SPR	Funds intended for planning and research purposes. SPR funding requires that States allocate 2 percent of their apportionments received from federal programs (e.g. Interstate Maintenance, NHS, Surface Transportation, Highway Bridge, CMAQ, et al.) for State planning and research activities. From this 2 percent, States must then allocate 25 percent for research, development, and technology (RD&T).
Statewide Transportation Improvement Program	STIP	The State’s four-year list of fiscally constrained transportation projects planned for implementation statewide.
Stopping Sight Distance	SSD	The minimum distance a driver can see ahead in tandem with how long it takes for her/him to stop. According to the AASHTO "Green Book", this distance is comprised of two components; 1. Perception-Reaction Time, which covers the distance a vehicle travels from the moment the driver sees an object necessitating a stop, to the instant the brakes are applied, and -- 2. Braking Distance, which is the distance a vehicle travels during the braking maneuver.
Strategic Highway Network	STRAHNET	A network of highways which are important for U.S. strategic defense policy and which provide defense access, continuity and emergency capabilities for defense purposes.
Strategic Highway Safety Plan	SHSP	Required by federal law (SAFETEA-LU, 2005), An SHSP identifies a State's key safety needs, whilst guiding investment decisions to achieve significant reductions in highway fatalities and injuries on all public roads. The SHSP facilitates all State highway safety programs to work in concert to align all its resources to collectively address safety challenges on all its public roads.
Sub-base (of Road)		The load bearing and distribution layer of a road underneath the pavement and capping layer. The sub-base is often made of an aggregate such as gravel or crushed-concrete, which is spread and compacted in-place during construction. A Sub-base might also be made of a bound concrete slab in the case of a weak subgrade, or when heavy loads are expected upon the roadway.
Subgrade (of Road)		Classically known as the "Formation Level", the subgrade of a road is the underlying layer beneath the sub-base. The subgrade is at the lowest level of excavation for a road structure and is leveled off to serve as the foundation. A good subgrade should be at least compacted soil that has a low-permeability.
Substantial Regional Impact	SRI	In the context of the State of Vermont planning practice, a proposed development has a Substantial Regional Impact (SRI) if a policy of this Regional Plan that is relevant to the determination of an issue in an Act 250 or Section 248 proceeding makes recommendations that are more specific about one or more characteristics, features, standards, or conditions relating to the proposed development than the recommendations of the municipal plan.
Subsystem		Within context of the architecture of the National Intelligent Transportation Systems (ITS) Architecture, subsystems are individual pieces of the ITS. Subsystems are grouped into four classes: Centers, Field, Vehicles, and Travelers. Example subsystems are the Traffic Management Subsystem, the Vehicle Subsystem, and the Roadway Subsystem. These correspond to the physical world: respectively traffic operations centers, automobiles, and roadside signal controllers. Due to this close correspondence between the physical world and the subsystems, the subsystem interfaces are prime candidates for standardization.
Sufficiency Rating		A measure of road or bridge adequacy. A section of road that is completely adequate in every respect is rated at 100. Any deficiency in the road that affects the structural condition, efficient movement of traffic, or safety reduces the rating as far down as zero.
Sulfur Dioxide	SO2	Petroleum fuels contain traces of sulphur compounds and produce Sulfur Dioxide (SO2) during combustion. The majority of the SO2 pollution comes from power generation, which is a significant cause of "Acid Rain". Except for the shipping mode, transportion is not a major contributing source of SO2.
Super Ultra Low Emission Vehicle	SULEV	A vehicle producing 90 percent less pollutants than an average gasoline-powered vehicle for the year of manufacture.
Supply Chain Consortium	SCC	A private-sector consortium which collects data, develops indicators, advises on "Best Practices" optimizing performance and profitability of a supply chain.
Supply Chain Management	SCM	Planning and management of business activities involved in movement of freight. SCM seeks to equalize supply and demand across all tiers of the chain (e.g. Supplier -- Primary Manufacturer -- Secondary Manufacturer -- Regional Warehouse -- Distributor -- Retailer -- Consumer).
Surface Transportation Program	STP	Federal program providing flexible funding for projects on any Federal-aid highway, including the NHS, bridge projects on any public road, transit capital projects, and bus facilities.
Swept Path Width		Amount of roadway covered in negotiating a turn; equals the "offtracking" width (i.e. The difference between the front and rear wheelpaths when a bus or truck is negotiating a turn) plus the tractor unit or bus width.

OTHER TRANSPORT TERMINOLOGY REFERENCES: