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Roles of Transportation Management Centers in Incident Management on Managed Lanes

Glossary of Terms

The national 3-digit telephone number for traveler information used by most states to provide real-time traffic and transit information about current operation status, highway conditions, weather advisories, and emergency warnings.

Active Traffic Management (ATM)
Method used to manage the flow of traffic on busy major highways to increase mobility and safety, and reduce congestion. Strategies include: variable speed limits, hard-shoulder running and overhead variable message signs.

Adjustable/Variable Speed Limits
Speed limit signs located along the roadway that can change to direct motorists to reduce speed when necessary. These signs can be adjusted by TMC personnel.

Adjusting vehicle eligibility requirements
Strategy in which an existing vehicle occupancy requirement can be increased, an eligibility requirement could be implemented where none normally exists, or a HOT facility could suspend access for those paying tolls and restrict entry to HOVs only.

Automated Enforcement
Enforcement used on managed lanes that reduce the need for manual enforcement such as law enforcement patrols. Strategies including automatic license plate recognition are utilized.

Automatic License Plate Recognition (ALPR)
Surveillance method that uses optical character recognition on images to read license plates on vehicles.

Bus Lane
Lane that only buses are permitted to use.

A road, or section of a road, set apart exclusively for buses.

Closed Circuit Television (CCTV)
The use of video cameras to view traffic on roadways. TMC operators have the ability to control these cameras to pan, tilt, or zoom to show different views of the road.

Computer-Aided Dispatch (CAD)
Program used by TMC personnel to gather information about an incident and dispatch the appropriate emergency personnel by taking into account the type of incident and responder agency needed.

A contraflow lane uses a lane in the off-peak direction of travel for travel in the peak direction, and is typically created using a movable barrier to separate the two directions of travel.

Continuous Access Lane
Motorists may enter and exit the lane at any location. May operate as a typical freeway lane with some form of access restriction, can be closed or operated as an additional general purpose lane.

Department of Transportation (DOT)
A government department responsible for construction, operation, and maintenance of highways, railways, and other forms of transportation.

Implemented in one of two ways where general traffic can be diverted into the managed lanes, or managed lane traffic can be diverted into the general purpose lanes.

Dynamic Message Sign (DMS)/Variable Message Sign (VMS)
Message signs used on roadways to communicate different types of information including incidents and travel times. TMC operators are responsible for entering the real-time information into the system to transmit these messages.

Express Toll Lane (ETL)
A priced managed lane that charges a toll for access to the lane. The toll rate is variable in order to manage congestion. Rate adjustments may be on a set schedule or dynamically based on real-time traffic conditions.

Eligibility Requirements Suspension
Strategy used to open the managed lanes to all traffic.

Facility Closure
Changeable message signs, signals, or gates at the entrances to the managed lane facility that is controlled by the TMC to completely close the facility to traffic.

Federal Highway Administration (FHWA)
A division of the United States Department of Transportation which oversees the construction, maintenance and preservation of the nation's highways, bridges and tunnels.

High Occupancy Toll (HOT) Lane
A priced managed lane where an occupancy requirement is set and those vehicles meeting that requirement can travel for free, and vehicles not meeting the occupancy requirement must pay a toll to travel in the lane. The toll rate for vehicles not meeting the occupancy requirement is variable in order to manage congestion.

High Occupancy Vehicle (HOV) Lanes
Lane with a vehicle restriction for the exclusive use of vehicles with a driver and one or more passengers, including carpools, vanpools, and transit vehicles. May operate at all times or only during peak hours.

Highway Advisory Radio (HAR)
Radio used to broadcast information to motorists.

Incident Management (IM)
Strategies designed to restore normal service operation safely and as quickly as possible following an incident while minimizing impacts.

Intelligent Transportation System (ITS)
A broad range of wireless and wire line communications-based information and electronic technology applications used by different modes of transport and traffic management.

Lane Control Signals
Green arrow and red "X" signals that appear over lanes to indicate if a lane is open or closed. On certain managed lanes, TMC personnel are able to remotely close and re-open lanes.

Managed Lanes
Highway facilities or a set of lanes where operational strategies are proactively implemented and managed in response to changing conditions.

Manual Enforcement
This type of enforcement involves placing law enforcement personnel along the managed lane to monitor traffic and stop motorists who violate policies.

Painted Buffer
Double white line or a wider painted "buffer area" used to separate a managed lane from the general purpose lanes, with openings to allow legal entry/exit points.

Painted Buffer with Electronic "Invisible" Barrier
Same as the painted buffer with the addition of an electronic system. This system can include a series of cameras, license plate readers, and/or toll transponder readers to detect when a car enters or exits the managed lane between legal entry/exit points.

Permanent Physical Barrier
A physical barrier used to separate the managed and general purpose lanes permanently. Designed so that the managed lanes will operate as a completely separate roadway from the general purpose lanes.

Plastic Post Barrier
Flexible plastic posts placed inside a painted buffer area to separate managed lanes and general purpose lanes.

Ramp metering
Used to reduce the volume of traffic entering the roadway.

Regional Architectures (RA)
Describes what type of TIM systems and services will be deployed and the information that is exchanged between them. Also identifies data and communications standards that apply.

Reversible Roadway
Entire roadways that can reverse direction and are typically built to handle large directional peaks in traffic volumes.

Road Weather Information System (RWIS)
Used to obtain weather information.

Roadway Management
Use resources to effectively manage the affected roadway and arterials during incidents.

Safety Service Patrol
Motorist assistance safety/service patrol programs that help keep incident scenes safe, clear incidents more quickly, and assist other emergency responders at incident scenes.

Scene Management
Strategies that involve the establishment of a safe and effective area where responders can deal with the incident response and clearance.

Shoulder Lane
Right or left shoulder lane is used as a full-time or part-time managed lane.

Strategic Plan
Identifies vision, goals and objectives for the managed lane TIM activities as well as deployment strategies, benefits and costs, funding plans and high level performance measures.

Toll Rate Adjustment
Dynamically adjusting toll rates that can increase the price for use of the managed lanes in order to discourage all but the highest value trips from utilizing the facility.

Traffic Control
Implementing effective traffic control at and around the incident management scene can help increase the safety of the responders as well as reduce the potential for secondary vehicle accidents.

Traffic Incident Management (TIM)
The process of coordinating the resources of a number of different partner agencies and private sector companies to detect, respond to, and clear traffic incidents as quickly as possible to reduce the impacts of incidents on safety and congestion, while protecting the safety of on-scene responders and the traveling public.

Transportation Management Center (TMC)
Center that provides real-time monitoring of the highway, detecting incidents, coordinating/supporting response and distributing traveler information. Normally open 24 hours a day, 7 days a week but are at least open during peak periods.

Zipper Barrier
A semi-permanent physical barrier for lane separation that can be moved by a special mobile machine.

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