Glossary terms

Active Demand Management (ADM)
The practice of proactively influencing facility demand based on a variety of approaches to encourage mode shift, trip changes, and to influence traveler behavior.
Active Parking Management (APM)
The dynamic management of parking facilities in a region to optimize performance and utilization of those facilities while influencing travel behavior at various stages long the trip making process: i.e., from origin to destination.
Active Traffic Management (ATM)
The ability to dynamically and proactively manage recurrent and nonrecurrent congestion on an entire facility based on prevailing traffic conditions.
Active Transportation and Demand Management (ATDM)
The dynamic management, control, and influence of travel demand, traffic demand, and traffic flow of transportation facilities.
Abbreviation for Active Demand Management.
Abbreviation for Active Parking Management.
Abbreviation for Active Transportation and Demand Management.
Abbreviation for Active Traffic Management.
Benefit/Cost Analysis
An analysis comparing all measureable consequences of a project by attributing them a monetary value.
Bus-bypass Shoulder
A shoulder exclusively accessible to transit busses either on a part-time or full-time basis.
The theoretical maximum amount of vehicles crossing a section of the highway in an hour.
Changeable Message Sign
See Dynamic Message Sign.
Abbreviation for changeable message sign.
The resources used to produce a good or service.
The increased travel time experienced due to circumstances that impede a desirable movement of traffic.
Abbreviation for dynamic message sign.
Dynamic Lane Use Control
An ATM measure consisting of opening a shoulder to traffic on a temporary basis to address capacity bottlenecks on the freeway network during times of congestion and reduced travel speeds. Also known as temporary shoulder use.
Dynamic Merge Control
An ATM measure consisting of allocating lane access on the general purpose lanes and ramps based on the traffic already present on the highway and merging traffic in order to provide priority to the facility with the higher volume and give a lane drop to the lesser volume roadway or approach.
Dynamic Message Sign
A permanently installed or portable electronic traffic sign used on roadways to give travelers information about roadway conditions. Often abbreviated as DMS.
Dynamic Parking Capacity
The practice of increasing the capacity of parking facilities through technology on a dynamic basis based on demand.
Dynamic Parking Reservation
The ability for travelers to utilize technology to reserve parking space at a destination facility on demand to ensure availability.
Dynamic Pavement Marking
An in-pavement traffic control device that can be activated to show alternative lane delineation.
Dynamic Pricing
The use of tolls that vary in response to changing congestion levels, as opposed to variable pricing that follows a fixed schedule.
Dynamic Rerouting
An ATM measure consisting of providing route information on overhead sign gantries along a roadway in response to recurrent and non-recurrent congestion.
Dynamic Ridesharing
The practice of offering a formal or informal service whereby travelers arrange one-time shared rides on very short notice by using advanced technologies, such as smartphones and social networks.
Dynamic Speed Limits
See Variable Speed Limits
Dynamic Traveler Information and Rerouting
The practice of utilizing real-time transportation information to convey current and impending traffic conditions to travelers as well as to proactively provide alternate route information to help minimize the impact of non-recurrent congestion.
Dynamic Truck Restrictions
An ATM measure that restricts trucks from using specific lanes on a facility, limiting their operating speed, and/or prohibiting their use of an entire facility during specific periods of the day.
Dynamic Wayfinding
Providing real-time parking-related information to travelers associated with space availability and location so as to optimize the use of parking facilities and minimize the time spend searching for available parking.
Dynamically Priced Parking
Parking fees that are dynamically varied based on demand and availability to influence trip timing choices and parking facility choice in an effort to maximize utilization and reduce the negative impacts of travelers searching for parking.
Emergency Refuge Area
The free space available beyond the shoulder to safely harbor vehicles in distress.
Function of maintaining the rules and regulations of a preferential treatment to maintain the integrity.
Feasibility Study
A study meant to assess whether a project is worth pursuing.
Federal Highway Administration.
Flow Profile
A figure showing the variation of traffic flow as a function of the time of the day.
General-Purpose Lanes
Lanes on a freeway or expressway which are open to all motor vehicles.
Hard Shoulder Running
See Temporary Shoulder Use or Dynamic Lane Use Control.
Highways Agency
Executive part of the Department of Transport responsible for operating, maintaining and improving the strategic road network in England on behalf of the Secretary of State for Transport.
The system of grade-separated ramps connecting two or more roadways.
Junction Control
See Dynamic Merge Control.
Lane Control Sign
A DMS placed on top of each lane on overhead gantry with the ability to show a green arrow (open lane), a yellow arrow (closing lane) or a red cross (closed lane).
Level of Service (LOS)
A qualitative measure that describes the operational conditions of a roadway or intersection.
Line Control
See Speed Harmonization.
Main Lane
A general purpose lane on a freeway that is open to all motor vehicles.
Motorway Incident Detection and Automatic Signaling (MIDAS)
A British incident detection and management program.
Motorway Traffic Management (MTM)
A Dutch incident detection and management program.
Any object or situation that might hinder the ability to use the roadway or shoulder safely.
On-Demand Transit
The practice of allowing a traveler to request a specific transit trip based on their individual trip origin and destination and their desired departure or arrival time.
Peak Hour
The hour in which the maximum demand occurs on a facility.
Peak Period
The period during which the highest volumes are observed daily on a regular basis.
Predictive Traveler Information
The practice of utilizing real-time and historical transportation data to develop algorithms to predict impending conditions and convey that information to travelers in advance of their trip in an effort to influence travel behavior.
Quality of Flow
See Level of Service (LOS)
A line of vehicles on a transportation facility.
Queue Warning
An ATM measure consisting of the display of warning signs and flashing lights along a roadway to alert drivers that congestion and queues are ahead.
Raised Pavement Markers
Traffic control devices, usually retroreflective, embedded in the pavement and meant to delineate lanes in addition to striping.
Ramp Metering
The procedures used to reduce congestion by managing vehicle flow from local-access on-ramps using a traffic signal at the entrance ramp that allows vehicles to enter the freeway at predetermined intervals.
Dutch ministry of transports and water management.
Rotating Sign
Sign that can show two or more messages by rotation of the panel is composed of.
An imaginary line delineating a disruption in vehicle speeds.
Speed Harmonization
An ATM measure consisting of using an expert system to monitor data coming from the field-deployed sensors on a roadway and automatically adjusting speed limits when congestion thresholds are exceeded and congestion and queue formation are impending; Sign gantries that span the facility provide speed limits and additional information depending on the roadway conditions.
Temporary Shoulder Use
An ATM measure consisting of opening a shoulder to traffic on a temporary basis to address capacity bottlenecks on the freeway network during times of congestion and reduced travel speeds. Also known as Dynamic Lane Use Control.
Traffic Management Center
A surveillance and control center for the road network in the area.
Traffic Volume
The amount of vehicles crossing a section of a road in a hour time.
Travel Time
The length of time it takes to travel between two points.
Travel Time Reliability (TTR)
A term referring to the variability in travel time that can be expected using different facilities.
Variable Message Sign (VMS)
See Dynamic Message Sign (DMS)
Variable Speed Limits (VSL)
Speed limits that change based on road, traffic, and weather conditions.
Vehicle Miles Traveled (VMT)
The total distance traveled in miles by all motor vehicles of a specific group in a given area at a given time.
Weaving Lane
A lane used for both merging on the highway and exiting the highway.