Transportation Glossary

The following is a listing of transportation-related terminology and phraseology developed by CCMPO.
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Term	Acronym	Definition
Rail Diesel Car	RDC	A self-propelled, diesel-powered rail passenger car originally built by the Budd Company of Philadelphia between 1949 and 1956 (also termed the "Budd Car"). This vehicle was the original "DMU". A remanufactured, Federal Railroad Administration-approved version is available to date.
Rail Sidings		Sidings increase the capacity of a single track. A single-track line has auxiliary tracks known as sidings. Sidings are located along the line, which allows trains moving in opposite directions to pass each other and allows faster trains to overtake slower trains. The capacity of the rail line and the reliability of operation are affected by the time required to move between sidings.
Rail-with-Trail	RWT	Also termed a "Rail-Trail", a RWT is a shared-use path located on, or abutting an abandoned or converted railroad line.
Recission		A congressional budgetary term refering to reduction or cancellation of previously granted funding.
Reclaimed Asphalt Pavement	RAP	Removed and/or reprocessed pavement materials containing asphalt and aggregate produced from pavement materials removed for resurfacing or reconstruction. When crushed and graded, RAP provides a high quality aggregate coated in asphalt that can be blended with conventional aggregates to create aggregate base and surface layer materials that produce roadways with good drainage characteristics and durability. Care must be taken when blending the RAP material with conventional aggregates as it has been found that above 20% to 25% RAP content decreases the strength of the roadway because less compaction of the blended material can be achieved. There are also unresolved environmental concerns regarding the leachability characteristics of RAP where it may be in contact with groundwater.
Record of Decision	ROD	A record of agreement that a proposed project meets all applicable requirements of an EIS. An ROD is issued by the designated lead agency in the study.
Regional Planning Commission	RPC	Enabled by state law, RPCs assist communities within their region to develop local and invoke regional comprehensive land use, transportation and economic development plans which have regulatory recognition in Vermont Act 250 land use proceedings and state agency planning efforts.
Request for Proposal	RFP	A formal invitation to organizations to bid on a scope of work for an outlined project.
Request for Qualifications	RFQ	A formal invitation to organizations to submit their qualifications and merits to undertake a scope of work for an outlined project.
Retroreflective		A type of material on signage or pavement markings used to optimize brightness for the nighttime driver. Retroreflective material make signage legible at further distances by reflecting most all of the light striking it from a light source directly back towards it. This reflection is contained in a narrow cone that spreads out wide enough to include the driver (almost directly behind a vehicle's headlamps). Hence, this special type of "back to the source" reflection is called “retroreflection”. A sign may be reflective, but without this engineered cone of retroreflection, it would be considered "diffuse reflection". When the viewer is not near a light source, many diffuse-reflecting materials will usually be brighter than retroreflective materials.
Ridership		Total number of "rides" taken by people using a public transportation system during a specified time period.
Ridesharing		Any form of shared commuting, which is not Public Transportation (e.g. carpooling, vanpooling, shuttle, etc.).
Right-of-Way	ROW	A pathway or road with a specific description (e.g. 'Access and egress 22 feet wide from the centerline of Main Road in Huntington'). ROW may also entail rights to cross property to go to and from another parcel, to pass across another's land, or right to cross without a specific description (e.g. a floating easement). Railroads own title to a right of way upon which to build permanent tracks.
Riparian Buffer		Riparian buffers are vegetated areas next to water resources that protect water resources from nonpoint source pollution (e.g. vehicles and other traffic) and provide bank stabilization as well as aquatic and wildlife habitat. Buffers can be a strip of grass, shrubs, and/or trees along the bank of a river or stream, which filters pollution and runoff, providing a transition zone between water and human land use.
Road Diet		A term used to convey phenomena of increased safety and reduced traffic congestion via a reduction in the number of travel lanes on a roadway, usually (but not always) from four lanes to three.
Road Surface Management System	RSMS	A program which assists local governments in identifying maintenance and repair strategies for roads.
Roadrailer		Type of equipment involving the use of rubber-tired track trailers fitted on to rail wheelsets, combined with other units to form a train.
Roadway Safety Audit Review	RSAR	A formal safety performance examination of a road or intersection by an multi-disciplinary team. An RSAR reports on potential safety concerns and investigates strategies to improve safety at the specified location. Issues that should be addressed in the report ought to include; 1. Aspects of a safety concern in or around the roadway, and 2. Opportunities to mitigate or eliminate identified safety concerns.
Rolling Stock		Total number of vehicles comprising a transit system (e.g. rail cars, busses, vans, etc.).
Rotary		A large, circular, one-way, multi-lane, and often higher-speed (above 30 MPH) intersection that commonly serves as an access and exit point to interstates, freeways, limited-access highways, or major arterials. Rotaries are NOT roundabouts. Most commonly found in the northeastern U.S., rotaries large size (> 600' width) and low deflection around their center island allow for high speeds (in some cases as high as 45 MPH). Because of this, and Right-of-Way often being given to entering vehicles, rotaries have much higher crash and injury rates than do the more modern Roundabouts.
Roundabout		Non-signalized circular intersection with specific design and traffic control features to ensure low travel speeds and efficient traffic movement.
Route Choice		The process of simulating the sequence of roadways an individual will choose for a trip, given the trip’s origin, destination, and mode.
Route-Miles		Total number of miles within a fixed-route transit system.
Rumble Strips		Rumble strips are raised or grooved patterns constructed on, or in travel lane and shoulder pavements. The texture of rumble strips is different from the road surface. Vehicle tires passing over them produce a sudden rumbling sound and cause the vehicle to vibrate. Road agencies use rumble strips to warn motorists of an upcoming change that may require them to act. For example, the need to slow down for a toll plaza ahead, change lanes for a work zone around the curve, stop for a traffic signal, or steer back onto the roadway. Rumble strips in travel lanes often precede intersections, especially dangerous ones. They are used primarily on expressways, interstate highways, and parkways, although some States install them on 2-lane rural roads that have high numbers of single-vehicle crashes.
Rutting		Surface depression along the wheelpath of a road caused by excessive wear. When rutting occurs, rainwater can collect in the wheelpath, which can lead to increased probability of hydroplaning.

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