Frequently Asked Questions

Glossary

• At-Grade - Describes a roadway that will be relatively close to the existing ground elevation and not elevated on a bridge structure.
• At-Grade Intersection - A point where two roadways meet and traffic is controlled by a traffic signal or stop sign.
• Auxiliary Lanes - Describes a lane that provides a driver the ability to speed up or slow down as needed to merge with traffic.
• Average Daily Traffic (ADT) - The average traffic volume in a 24-hour period on a particular roadway.
• Collector Distributor Roadway - a one-way road next to a highway that is used for some or all of the ramps that would otherwise merge into or split from the main lanes of the highway. It is similar to a frontage road, but is built to freeway standards. It is used to eliminate or move weaving from the main lanes of the highway.
• Collector Roadways - These roadways provide service to any county seat, large towns, or other major traffic generators not served by the arterial system. They provide links to the higher classified routes and serve as important intra-county travel corridors.
• Corridor - A corridor is a broad geographical band with no predefined size or scale that follows a general directional flow connecting major sources of trips. It involves a nominally linear transportation service area that may contain a number of streets, highways, and transit route alignments.
• Express Lanes (Managed Lanes) -Highway facilities or a set of lanes in which operational strategies are implemented and managed (in real time) in response to changing conditions. Managed lanes are proactively implemented, managed, and may involve using more than one operational strategy; Possible examples of managed lanes may include the following: High Occupancy Toll (HOT) lanes with tolls that vary based on demand; exclusive bus- and truck-only lanes; High Occupancy Vehicle (HOV) and clean air and/or energy-efficient vehicle lanes; and HOV lanes that could be changed into HOT lanes in response to changing levels of traffic and roadway conditions.
• Grade Separated Intersection - A point where two highways or a highway and railroad meet, and the through traffic/train from each facility is separated by an overpass/underpass.
• Higher Class Roads - Facilities that are mostly free-flowing with controlled or limited access and higher speeds. Examples are Interstate Highways/Freeways and Principal Arterials.
• Level of Service - Operating conditions within a stream of traffic describing safety, traffic interruptions, speed, freedom to maneuver, comfort, and convenience. Six levels of service are defined, designated A through F, with A representing the best conditions and F the worst.
• Lower Class Roads - Facilities with multiple at-grade intersections, minimal access management, and lower speeds. Examples are minor arterials and collector roadways.
• Managed Lanes (Express Lanes) -Highway facilities or a set of lanes in which operational strategies are implemented and managed (in real time) in response to changing conditions. Managed lanes are proactively implemented, managed, and may involve using more than one operational strategy; Possible examples of managed lanes may include the following: High Occupancy Toll (HOT) lanes with tolls that vary based on demand; exclusive bus- and truck-only lanes; High Occupancy Vehicle (HOV) and clean air and/or energy-efficient vehicle lanes; and HOV lanes that could be changed into HOT lanes in response to changing levels of traffic and roadway conditions.
• Minor Arterials - These roadways interconnect and supplement the principal arterial system with a greater emphasis on land access and a lower level of traffic mobility. They provide intra-community service and connect rural collector roadways to the urban highway system.
• Principal Arterials - These roadways provide an integrated network of roads that connect principal metropolitan areas and serve virtually all urban areas with a population greater than 25,000. They serve long distance travel demands such as statewide and interstate travel. Principal arterials can be grouped into freeway principal arterials and non-freeway principal arterials.
• Right of Way - A strip of land that is granted through an easement or other mechanism for transportation purposes such as a highway.
• Transportation Demand Management - Behavioral changes to commuters' travel habits that result in fewer vehicles during peak hours. Examples would be carpooling/vanpooling, employee trip reduction programs, compressed work weeks, telecommuting, flex-time, and employer incentives.
• Transportation System Management - Management to make the existing transportation system as efficient as possible. Examples would be park-and-ride lots, ridesharing, HOV facilities, traffic signal coordination, and intersection improvements.
• Travel Demand - The number of users desiring to travel the highway system based on the available roadway network.
• Volume to Capacity (V/C) - The ratio of current traffic flow rate to capacity of a specified roadway or section of roadway.
• Vehicle Hours Traveled (VHT) - The time (in hours) that users spend on the roadway system during a specific time period.
• Vehicle Miles Traveled - The measurement of the total miles traveled by all vehicles in a specified area during a specified time.