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Traffic Control Terminology

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Tab Sign
A sign smaller than the primary sign with which it is associated, and mounted below it. There are two types of tab signs:

(1) Supplementary Tab Sign - contains additional, related information:

(2) Educational Tab Sign - conveys the meaning of symbols during their introductory period.

TAC
Transportation Association of Canada.

Tangent
In Temporary Conditions, the distance between the end of one taper and the beginning of the next taper, where more than one lane is being closed.

Taper
The gradual narrowing of a lane which is intended to safely guide drivers into the adjacent lane. The taper length is the length of the section of roadway required to achieve full lane closure (e.g., construction zone) or full lane transition.

TDM
Travel Demand Management.

Temporary Bridge
A modular steel truss bridge often used on construction sites due to its ease and speed of installation and removal, often having a single, narrow lane.

Temporary Conditions
Roadway and traffic control conditions related to nonpermanent construction, maintenance and utility work on any highway open to the public.

Temporary Pavement Marking
A Pavement Marking intended to be used for Temporary Conditions.

Temporary Sign
A Regulatory, Warning, or Guide Sign, intended to be used for Temporary Conditions.

Temporary Traffic Control Signal
A temporary traffic control signal installed to control traffic at a crossing, such as a temporary roadway, a truck access route, pedestrian crossing, etc., and must comply with Section 144(31) of the Highway Traffic Act. The design specifications for temporary signals, which require approval from the appropriate road authority, are those specifications which apply to permanent traffic control signals at signalized intersections.

Termination Area
The sixth and last component of a work zone, downstream of the work area, used for traffic to make the transition back to the normal path of the road. The termination area extends from the downstream end of the work area to the point where traffic is able to resume normal driving.

Textured Crosswalk
The use of textured material (coloured paving stones or paved concrete) that contrasts with the adjacent roadway, thereby visually demarcating the pedestrian crosswaIk area.

Thermoplastic
A class of pavement marking material whose main component is a plastic material that becomes pliable or liquid at high temperatures.

Third-party Sign
Commercial advertising on street furniture (such as bus shelters) or elsewhere on the highway right-of-way for commercial products or services available at a location other than where the sign is located.

Through Band (Traffic Signal)
The time period between the passing of the first and last possible vehicle in a group of vehicles moving in accordance with the designed speed of a signal progression.

Through Roadway
(1) The portion of the roadway used by through traffic as opposed to the parts used by traffic which is stopping or turning- or

(2) A road at which vehicular traffic from intersecting roads is required to stop before crossing or entering.

Through Traffic
(1) Traffic using a through roadway or

(2) Traffic proceeding through an area and not having an origin and destination therein.

Time Base Control (Traffic Signal)
A means for automatic selection of modes of operation of traffic control signals in a manner prescribed by a predetermined time schedule.

Time-based Coordination (Traffic Signal)
A means of providing traffic signal progression along a route based on pre-set timed intervals between sequential traffic signals, rather than on communications from a master controller or control computer.

Time of Day Control
The practice of using a different traffic signal system
timing plan for each defined time period in the day.

Time of Operation
The time period for which a traffic system is in operation, or during which a prohibition or restriction is in effect.

Time-separated Pedestrian Facility
A pedestrian facility where pedestrians are controlled and protected from other users by "time-sharing" the facility, such as by traffic signals or school-crossing guards.

Time Waiting Gap Reduction
See Gap Reduction (Traffic Signal).

Timing
When referring to traffic signals, timing describes the amount of time allotted to each Phase within each signal cycle.

TMA
Truck-mounted Attenuator.

TMC
Traffic Management Centre.

TOC
Traffic Operations Centre.

TOD
Time of Day.

Toll Highway
A highway, often built to freeway configuration, where a fee (toll) is charged for use of the highway.

Tourism Oriented Destination Signing (TODS)
A program of tourism signing developed for provincial highways with trailblazing continuity on other roads. Some municipalities have developed municipal tourism signing programs compatible with TODS.

Tourism Signing
Information signing for tourist-related attractions. Tourism signing includes TODS as well as non-TODS signing for local and municipal attractions.

TRACS
Traffic Adaptive Control Systems.

Traffic Accident
See Collision.

Traffic Adaptive Control System (TRACS)
A system that is responsive to traffic demands, which automatically adjusts itself to adopt optimum control parameters such as cycle length, split and offset, at very short intervals, to optimize operation at an intersection almost on a cycle by cycle basis. This means it can, at the microscopic level and at short term variation, provide the most efficient management of traffic signals, either at a single isolated junction or a network or group of junctions commonly known as sub-systems or sub-areas.

Traffic Calming
The combination of mainly physical measures that reduce the negative effects of motor vehicle use, alter driver behaviour and improve conditions for non-motorized street users.

Traffic Calming Measure
A physical device, regulation or other action which affects the movement of motor vehicles, bicycles, and/or pedestrians.

Traffic Circle
A confluence of three or more intersection legs at which traffic merges into and emerges from a one - way roadway in a counterclockwise direction around a central area. Traffic circles are typically used on local streets, and may have either no right-of-way control devices, or YIELD signs. See also Roundabout.

Traffic Control Device
Any sign, signal, marking, or device placed upon, over or adjacent to a roadway by a public authority or official having jurisdiction, for the purpose of regulating, warning, guiding or informing road users.

Traffic Control Installer
A person duly trained and authorized to install and remove Traffic Control Devices at a Work Zone.

Traffic Control Manual for Roadway Work Operations
The old MUTCD Temporary Conditions Field Edition, superseded by the portable, abbreviated Field Edition of Book 7, published March 2001.

Traffic Control Person (TCP)
A person duly trained and authorized to direct traffic at a work zone through the use of the Traffic Control Sign (STOP/SLOW Paddle).

Traffic Control Plan
A detailed plan for the control of traffic during construction, maintenance, or utility operations on a highway, taking into account the organized, systematic, safe conduct of the project, including, as applicable, detours, staging sequences, work vehicle access to and egress from work sites, temporary barriers, removal of old pavement markings and selection and planned implementation of appropriate typical layouts for traffic control.

Traffic Control Signal (Traffic Signal)
Any power-operated Traffic Control Device, whether manually, electrically or mechanically operated, by which traffic is alternately directed to stop and permitted to proceed. Traffic Signal-.

(1) When used in general discussion, a traffic signal is a complete installation including signal heads, wiring, controller, poles and other appurtenances.

(2) When used specifically, the term refers to the signal head which conveys a message to the observer.

(3) That part of a traffic control signal system that consists of one set of no less than three coloured lenses, red, amber and green, mounted on a frame and commonly referred to as a signal head.

Traffic Count
A record of the number of vehicles or people aboard vehicles, or both, and pedestrians that pass a given checkpoint during a given time period.

Traffic Island
A raised or painted island designed to separate streams of vehicular traffic.

Traffic Management
The management and control of traffic on traffic facilities, typically on major highway corridors and networks. See Book 19.

Traffic Offence
A violation of a traffic law, regulation or by-law which may result in a charge by police and a fine.

Traffic Operations Centre (TOC)
The centre comprising the main FTMS computer subsystem and operations centre.

Traffic Paint
A pavement marking material that consists mainly of a binder and a solvent. The material is kept in liquid form by the solvent, which evaporates upon application to the pavement, leaving the binder to form a hard film.

Traffic paints are classified by, among other things, drying time:

(1) instant dry - less than 30 seconds no track time,-

(2) quick dry - 30 to 120 seconds no track time:

(3) fast dry - 2 to 7 minutes no track time-,

(4) conventional - over 7 minutes no track time. See also Water-based Paint.

Traffic Protection Plan
A plan required by the OHSA and its regulations for the protection of workers in a work zone. The plan must contain a written description of the traffic hazards to which workers may be exposed and measures used to protect them.

Traffic Sign
A device (other than Markings, Delineators and Traffic Control Signals) which may be erected beside or above a roadway for the purpose of regulating, warning or guiding traffic.

Traffic Signal
See Traffic Control Signal.

Traffic Signal Control
The use of traffic signal control devices to control traffic on a road section or intersection.

Traffic Signal Controller
The general usage term for the controller unit, cabinet and associated appurtenances.

Traffic Signal Control System
An area or corridor signal system under centralized control.

Traffic Signal Timing
When referring to traffic signals, timing describes the amount of time allotted to each Phase within each signal cycle.

Trailblazer
A small identification sign which provides continuity and assurance for drivers wishing to follow a given route or to reach a given destination.

Trailer
A vehicle that is drawn upon a highway by a motor vehicle, except an implement of husbandry, a mobile home, or motorcycle side car.

Transceiver
A transmitter and receiver combined in one device,/,

Transit
Another term for public transportation.

Transition Area
The third component of a work zone, downstream from the approach area, and upstream of the longitudinal buffer area, where traffic is channelled from the normal path to a new path required to move traffic past the work space. The transition area contains the tapers and parallel tangent sections (if more than one lane closed) that are used to close the lanes effectively.

Transit Lane
A street or highway lane intended exclusively or primarily for transit vehicles, including buses, streetcars and trolleys, either all day, or during specified periods.

Transit Priority
A means by which transit vehicles are given an advantage over other traffic (e.g., pre-emption of traffic signals or bus priority lanes).

Transit Vehicle
A vehicle used by a public transportation authority for the transport of patrons.

Transitway
A dedicated right-of-way that is used by transit units (vehicles or trains).

Transponder
A small electronic device which, when mounted in or on a vehicle and interrogated electronically by a roadside reader, responds with its transponder identification and possibly additional information, enabling the reader to identify the passage of a specific vehicle. (Used in electronic toll collection systems and other applications.)

Travelled Roadway
See Roadway.

Travel Speed
Rate of motion. Ratio of travel distance and travel time.

Travel Time
The time of travel, including stops and delays except those off the travelled way.

TRL
Transport Research Laboratory.

Trolleycar
See Light Rail.

Truck
A commercial vehicle exceeding a specified weight or length as defined by the Highway Traffic Act, municipal by-law, or toll agency.

Truck-mounted Attenuator (TMA)
An energy-absorbing device mounted on the rear of a truck, to deform on impact in a controlled manner, thereby reducing.

(1) the rate of deceleration (and associated injury) for the occupants of a vehicle striking the TMA from the rear; and

(2) the rate of acceleration (and associated injury) for the driver of the truck.

TMAs must satisfy the requirements of NCHRP 350 Level TL-2 (70 km/h) or TL-3 (100 km/h), and should be selected for the appropriate posted speed. After January 1, 2006, all TMAs used on freeways must satisfy the TMA TL-3 requirement (100 km/h).

Turn Control Sign
A Traffic Sign, generally erected at an intersection, indicating by arrows and an Interdictory Symbol the movement or movements traffic on that approach must not take. These signs should not be confused with Lane Designation Signs.

Turning Movement Count
A traffic count at an intersection wherein the arriving and departing direction of travel is recorded.

Turn Lane
A lane designed to facilitate vehicular turn movements from the through roadway.

Turn Prohibition
A regulation prohibiting a straight-through movement or a left or right turn at an intersection. Turn prohibitions are sometimes used in association with barriers that physically prevent a turn from being made.

Turn Sign
A Warning Sign used to inform drivers of an upcoming change in roadway alignment. See also Curve Sign.

Turn Signal
A lamp on a motor vehicle used to indicate to other motorists a change in direction or change of lane by emitting a flashing light on the side of the vehicle towards which a turn will be made.

Two-lane Highway
An undivided two-way facility having one lane for traffic moving in each direction.

Two-way Left-turn Lane
The centre lane on some three, five or seven lane sections of undivided highway which is designed to facilitate left turns from each direction.

Uncontrolled Intersection
An intersection which does not have right-of-way control devices on any of the approaches.

Underpass
A grade separation where the travel way in question passes under another travel way.

Undivided Highway
A multi-lane highway with no continuous median, or with a paved flush dividing strip (including a Rumble Strip), or with a two-way left-turn lane.

Unidirectional Bikeway
A o n e-way bikeway.

Uniformity
Consistency in the design and application of traffic control devices and operations.

Unit Extension Time (Traffic Signal)
The timing period during the extendible portion of a right-of-way interval which is resettable by each detector actuation within the limits of the maximum period (extension limit).

Unposted Speed Zone
A section of highway upon which maximum speed signs are not erected and where a Statutory Speed Limit is in effect.

Upstream
The direction that traffic is coming from.

Upstream End (of an Island)
See Approach Nose.

Urban Area
An indefinite area of land used primarily for residential, commercial, and/or industrial purposes, usually associated with a given area size, population, and density.

Urban Bikeway
A Bikeway within an Urban Area.

Urban Highway
Any highway, road, or street within the boundaries of an Urban Area.

Urban Traffic Control Systems (UTCS)
A PC-based traffic control system that provides centralized road and intersection monitoring and traffic flow optimization, used in several major cities.

User-definable Parameters (Traffic Signal)
Parameters which can be modified on-line by the user via some interactive dialogue with the system.

UTC
Urban Traffic Control.

UTCS
Urban Traffic Control Systems.

Utility Corridor
A strip of land reserved for specific utilities (e.g., water, electricity, telephone). The corridor may be located adjacent to, over, under, or across the roadway.

UTM
Urban Traffic Management.

Vanpool
An arrangement in which a group of people share the use and cost of a van in travelling to and from prearranged destinations together.

Variable Message Sign (VMS)
A specific subset of Dynamic Message Signs. VMSs provide the highest level of functionality of all of the DMSS. VMSs contain a variable display, made up of a grid or matrix of discrete dots, known as pixels. Combinations of pixels render the appearance of a continuous formed character or graphic symbol. The VMS can display a full array of alphanumeric characters and symbols to form message combinations and can also have full graphics capability.

VDS
Vehicle Detection System. See Embedded Detector.

Vehicle
Includes a motor vehicle, trailer, traction engine, farm tractor, road-building machine, bicycle, and any vehicle drawn, propelled or driven by any kind of power, including muscular power, but does not include a motorized snow vehicle or motorcycle sidecar.

Vehicle Detection System (VDS)
See Embedded Detector.

Vehicle Eligibility
Eligibility of a vehicle to use a reserved lane or parking space, based on meeting defined criteria.

Vehicle Occupancy
The number of persons, including the driver and passenger(s), in a vehicle at a given time.

Vehicles with Lugs
See Lugs.

Very Short Duration (VSD) Work
Any work activity which occupies a fixed location for up to 30 minutes duration, including set-up and takedown of the traffic control provisions (e.g., some utility work, minor road maintenance, stormwater catchbasin cleanout, etc.). The work site may be moved along the road and make frequent, short stops

Vision Triangle
See Intersection Sight Distance.

VMS
Variable Message Sign.

Volume
The number of vehicles or pedestrians that pass over a given section of a lane or a roadway or make a particular movement during a specific time period (such as one hour or 24 hours).

Volume-Capacity Ratio (WC Ratio)
The ratio of demand flow rate to capacity for a traffic facility.

VRC
Vehicle-Roadside Communications.

Walkway
See Pedestrian Walkway.

Warning Sign
A sign which indicates conditions on or adjacent to a highway or street that are actually or potentially hazardous to traffic operations.

Watchdog (Traffic Signal)
A circuit or timer that is used to watch that an appropriate action is taken on a regular basis.

Water-based Paint
A Traffic Paint that employs water as a solvent, thus nullifying the environmental concerns with many traffic paints. Also referred to as latex. See also Traffic Paint.

Weigh-in-Motion (WIM)
Technology that enables vehicle weights to be determined without the need for a vehicle to physically stop on a scale. High-speed WIM (HSWIM) enables trucks to be weighed at highway speed. Mainline WIM incorporates the use of Automatic Vehicle Identification.

Wheelchair Accessible Vehicle
A vehicle that a wheelchair bound person may enter either:

(1) Via an on-board retractable lift or ramp"

(2) Directly from a station platform reached by an elevator or ramp that is either level with the vehicle floor or can be raised to floor level.

See also Para-transit.

Wide Curb Lane
A roadway lane which is wider than a normal lane for shared use by bicycles and motorized traffic, characterized by a curb-lane which is of such width that a bicycle and motorized traffic can be accommodated side by side in the same lane.

Wide Line
A pavement marking line wider than the standard 10 cm width, typically 20 cm, up to 30 cm, in width. See also Continuity Line.

Work Area
The fifth component of a work zone, downstream from the longitudinal buffer area and upstream of the termination area, where the work takes place. It is set aside for workers, equipment and material storage.

The work area may be in a fixed location or may move as work progresses. It may be defined by delineation devices. In a confined location, the work space may be shielded by barriers as an additional feature.

Work Site Identification
Visible identification of the work area by passive and/ or active traffic control devices to show road users where work is taking place.

Work Zone
A section of highway or roadway where highway related construction, maintenance, or utility work takes place. A work zone is usually made up of six component areas (See Figure 1), including the Work Area where the work takes place. A work zone can be in the travelled portion of the road or on the boulevard or shoulders and may be stationary or mobile. See Mobile Operations, Very Short Duration, Short Duration, and Long Duration Work.

Yield (Traffic Signal)
A command which permits a Controller Unit to transfer right-of-way.