Transportation Glossary

The following is a listing of transportation-related terminology and phraseology developed by CCMPO.
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Term	Acronym	Definition
Paratransit		Flexibly-scheduled transportation services catering to special needs populations such as the elderly and disabled.
Park & Ride Facility	P&R	A parking lot designated by the state or a municipality for the purpose of commuter travel, allowing for a mode shift from automobile to transit or carpool. According to the 2004 CCMPO Park & Ride Prioritization Plan, there is a distinction between an "Intercept" (or "Satellite") lot and a "Park & Ride" lot. A Park & Ride lot's purpose is for car and vanpooling with potential for low frequency shuttle or transit service. It may serve multiple trip destinations. It is characterized by its suburban or rural location, a surface lot (v.s. parking structure), and low to medium capacity. The private car is the dominant method of trip collection and distribution. These facilities are implemented through public funding. The purpose of an "Intercept Lot" 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.
Parking Accumulation		Total number of vehicles parked within a parking facility at a given time, usually during peak use.
Partial Zero Emission Vehicle	PZEV	A vehicle that has zero evaporative emissions from its fuel system, has a 15 year (or at least 150,000 mile) warranty, and meets SULEV tailpipe emission standards.
Particulate Matter	PM	An indicator used in the description of Air Quality assessment. PM is a term describing a mixture of solid particles and liquid droplets monitored in the air. PM originates from fuel combustion from automobiles, power plants, industrial facilities, and residential fireplaces and wood stoves. Fine particles (PM 2.5 = 2.5 microns or smaller) are closely associated with health effects, such as; increased hospital admissions and emergency room visits for heart and lung disease, increased respiratory symptoms and disease, decreased lung function, and premature death. Larger particles (PM10 = 2.5 - 10 microns) generally occur as smoke, dust, pollen, etc., which settle relatively quickly when compared to fine particles.
Parts per Million	PPM	A measure of air pollutant concentrations.
Passenger Car Equivalents	PCE	Traffic engineering/modelling practice of converting Trucks, Buses and RV's to cars for the purpose of Capacity or Level of Service (LOS) analyses. More information on this topic may be found in the Highway Capacity Manual (HCM).
Passenger Facility Charge	PFC	A surcharge added to the price of an airfare and used for capital improvements at airports.
Passenger Miles Traveled	PMT	1. AIR MODE: One passenger transported 1 mile; passenger-miles for one inter-airport flight are calculated by multiplying aircraft miles flow by the number of passengers carried on the flight. The total passenger-miles for all flights is the sum of passenger-miles for all inter-airport flights... 2. AUTO MODE: One passenger traveling 1 mile; e.g., one car transporting two passengers 4 miles results in 8 passenger-miles... 3. TRANSIT MODE: The total number of miles traveled by transit passengers; e.g., one bus transporting five passengers 3 miles results in 15 passenger-miles.
Pavement Condition Index	PCI	A rating from 0-100 (with a corresponding qualitative rating from 'Failed' to 'Good'), reflecting the condition or level of wear of pavement along a road segment.
Peak Hour Factor	PHF	PHF is used to evaluate roadway capacity. It is the ratio of of total hourly volume to the maximum 15 minute rate of flow within the hour, that is; PHF = Hourly Volume / Peak Rate of Vehicle Flow (within the hour).
Peak Oil		A term refering to the "Peak" of global petroleum production (i.e. location, extraction, and refinement of oil). Though it does not refer to petroleum depletion per se, it does consider the reduction of its finite reserves. "Peak-Oil" alludes to the ever more difficult means for extraction and supply of inexpensive oil to which the staus-quo global economy relies. It further considers the time when it requires the energy of one barrel to extract a barrel of oil.
Peak Period/Peak Hour		The time period (or specific hour) during which the roadway carries the greatest number of vehicles. Traffic impacts are typically evaluated during the morning and afternoon peak hours when the greatest numbers of motorists are traveling to and from work. It may be specified as the morning peak period (traditionally 7-9 AM) or evening (4-6 PM) peak.
Peak Spreading		A Travel Demand Forcasting modeling concept where there is a calculation of a time-of-day shift in the peak period (i.e. when the maximum amount of traffic occurs). Where many travel demand models use only PM peak hour data (anywhere from 4-6 PM), a peak-spreading travel demand model uses an entire day of data (e.g. a "Day-based model" as opposed to a "PM peak model") to calculate this figure.
Pedestrian Environmental Factor	PEF	In traffic modeling, the PEF identifies the pedestrian and bicycle-friendly parts of the transportation network.
Perception, Identification, Emotion, and Volition	PIEV	According to the Institute of Transportation Engineers (ITE), PIEV times range from 2.5 sec. for general warning signs to 14.5 sec. for signs requiring a high degree of judgment from the driver. PIEV Distance may be expressed as: dp = 1.47 × V × t, where dp = Perception-reaction distance in feet, V = Speed in miles per hour (mph), t = Perception-reaction time in seconds, and 1.47 is a factor to convert speed from miles per hour (mph) to feet per second (fps).
Perception-Reaction Time	PRT	PRT outlines four distinct processes a driver must perform for roadway navigation; Detection, Identification, Decision, & Response. Where PRT varies widely among drivers, AASHTO suggests it to be 2.5 seconds (where 90% of drivers will have a PRT as fast as, or faster than 2.5 seconds). ITE suggests it is 1.0 seconds (where 85% of drivers would have as an aspect of reacting to signal timing, but it would be considerably higher for a braking response upon a highway). Other factors that influence a PRT are; age, fatigue, complexity of reaction, and alcohol.
Person Trip		The movement of a person from an origin to a destination. A carpool carrying three people from origin-to-destination make one vehicle trip, its occupants together have made three person trips.
Personal Rapid Transit	PRT	An energy-efficient, on-demand, guided route, mass-transit system, utilizing small, independent vehicles (e.g. Podcars).
Piggyback Service		A rail and truck combination service where a shipper loads a truck trailer, a truck delivers it to a rail terminal where it is loaded on a flatcar. The railroad then hauls the Trailer-on-Flatcar (TOFC) to a destination terminal, where it is offloaded and trucked to the consignee.
Planning Funds	PL	Funds intended for planning purposes only. Such funds are intended to be exclusive of design or engineering of transporation projects, as well as operations or right-of-way acquisitions. Planning funds may however, be used for project scoping.
Portland Cement Concrete	PCC	Portland Cement Concrete is a durable, but complex substance commonly refered to as "concrete".
Preliminary Engineering	PE	Project development phase in which project design is determined.
Project Definition Team	PDT	Comprised of various VTrans department heads who review transportation projects.
Project Development Process	PD	Otherwise known as "Scoping", the Project Development life-cycle of a transportation project generally has several steps: 1. Local Concerns Meeting. 2. Data Collection. 3. Alternatives Development. 4. Alternatives Presentation Meeting. 5. Alternatives Selection. 6. Report Preparation. 7. Report Acceptance by the State DOT (i.e. VTrans) Project Definition Team (PDT).
Property Damage Only	PDO	A reportable crash, which does not result in any fatalities or noteworthy injuries.
Public-Private Partnerships	PPP	Contractual arrangements between government agencies and private-sector entities to finance transportation projects.

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