Traffic Operation Definition of Terms
Abrasion - a condition manifested in pavement markings by gradual surface erosion, thinning, and disappearance of the film due to wind, water, sand, and vehicle tire wear.
Acceleration - a rate of change of speed resulting in an increase in travel speed.
Acceleration lane - a speed change lane for the purpose of enabling vehicle entering a roadway to increase its speed to a rate at which it can safely merge with through traffic, providing the necessary merging distance, and giving the main road traffic the necessary time to make appropriate adjustment.
Acceleration marks - marks that are just opposite the skid marks.The tires are being rotated by the axle and when done fast enough, the outside of the tire, the thread, takes time to catch up to the rest of the tire, which is being held by the coefficient of friction between the tires and the road surface.Therefore, the acceleration marks are heavy at the beginning and lighten up as the tire thread catches.
Access - a way of entering or traveling towards a location.
Actuation - the operation of a detector in registering the presence or passage of a vehicle or pedestrian.
Advance warning area - the first component of a work zone, upstream of the approach area, used to alert drivers to road work ahead.
Advisory maximum speed - an advisory speed posted when the roadway geometries result in a maximum safe speed which is 20 km/hr or more below the operating speed and is 10 km/hr or more below the regulatory speed limit.
Advisory speed - the speed, determined to the nearest 5 km/hr at which traffic may safely negotiate a potential hazard under favorable driving conditions.
A.I.D. - automatic incident detection.
Anti lock breaking system - (ABS) breaking system designed to break to break the vehicle in the most effective manner, without locking up the tires and causing the tires to go into a skid.This system is used differently than standard breaks when breaking in an emergency situation.The break pedal is stepped on and held in place while the electronic system takes over and modulates or applies the brakes until the wheels want to lock up and then releases and breaks again.
Base drawing - The scale drawing made of the accident scene that shows all the landmarks and detail to set the scene. It generally does not contain any measurements or any points of impact (POI) or points of rest (POR)
Bottleneck - a highway section with reduced capacity that experiences operational problems such as congestion.
Boulevard - an improved strip of land between the roadway and the sidewalk or between two opposing roadways.
Bull nose - the area or point of divergence between two diverging roadways such as between free way mainline lanes and an exit ramps.
Bumper fracture - fractures that typically occur due to the impact of a vehicle on the calves of a decedent with fractures of the tibia or fibula.They may be unilateral or lateral.
Call box - a telephone pr other communications device located a given locations along the side of the freeway.Motorists can request various services such as police, fire, or ambulance by pressing certain buttons or using voice communications.
Carbon dioxide - a molecule consisting of one atom of carbon and two atoms of oxygen,which is a major combustion product of the burning of organic materials.Carbon dioxide is the result of complete combustion of carbon.
Carbon monoxide - a colorless, odorless, very toxic gas formed by burning carbon or organic fuels.A gaseous molecule having the formula CO, which is the product of incomplete combustion of organic materials.
Carpool - an arrangement in which a group of people share the use and possibly the cost of a car in traveling to and from pre-arrange destinations together.
Causeway - a bridge or raised way constructed over marshy land or water.It may be either an earth fill or bridge type structure.
Center lane facility - a reserved lane at or near the center of the roadway.
Chemical etching - a form of texturing a mold utilizing an acid bath that erodes selective portion of the metal, leaving a resulting texture or pattern.
Chicane - a series of curb extensions on alternating sides of a roadway, which narrow a roadway and requires vehicle to meander to travel through the chicane. Typically, a series of three curb extensions is used.
Chop shop - a location, often an automobile repair shop or salvage yard, where a stolen car is stripped of its parts (radio,doors,engine,etc) the remains are cut up and sold for scrap metal.
Citation - a ticket issued by an officer deputized by the LTO for violating traffic laws.
Collision - an incident resulting in property damage, personal injury or death, and involving the loss of control and/or the striking of one or more vehicles with another vehicle, person, an animal, or an inanimate object.
Collision,primary - the impact between and another vehicle or a vehicle and a fixed object.
Collision,secondary - the impact between the occupant
Collision,tertiary - the impact between the occupant and the restraint system.
Corrosion - the degradation of metals or alloys due to reaction with the environment.The corrosive action on the metals or alloys is accelerated by acids, bases, or heat.
Crosswalk - (pedestrian crossing) is a designated point on a road at which some means are employed to assists pedestrians wishing to cross.
Curb - a vertical or sloping member along the edge of the roadway clearly defining the roadway edge.
Declination - the difference between true north as shown on a topographic map and magnetic north as indicated by the magnetic needle on a compass.
Drag factor - comes from the tool used to determine the value of the coefficient of friction of the road surface.A portion of a concrete-weighted tire is pulled or dragged along the roadbed by a "fish scale"The investigator reads the scale and and divides by the weight of the tire to determine the coefficient of friction.It is called dragged factor because it is determined by dragging the tire.
Driveway - every entrance or exit used by vehicular traffic to or from lands or buildings abutting a highway.
DUI - driving under the influence.
DWI -driving while intoxicated.
Dyslexia - a disturbance to the ability to read.
Efface - to rub out, to strike, scratch out, or to erase.
First responder - the initial responding law enforcement officer or other public safety official or service provider arriving at the scene prior to the arrival of the investigator in charge.
Footbridge - (pedestrian bridge) is a bridge designed for pedestrians and in some cases cyclists, animal traffic rather than vehicular traffic.
Footpath - is a path along the side of the road.
Gross weight - the weight of the vehicle without load plus the weight of any load thereon.
Intersection - is a road junction where two or more roads either meet or cross at grade.(same level)An intersection maybe 3 way, T-junction, fork, 4 way, cross roads, 5 way or more.
Laned roadway - a roadway is which is divided into two or more clearly marked lanes for vehicular traffic.
Longitudinal axis - the long axis of the vehicle that runs from the front (hood) to the rear (trunk) of the vehicle.
Metallic paint - paint used for covering metal surfaces, the pigment is usually iron oxide.
Meter - the basic unit of length in the metric system.
Motor vehicle - (road vehicle) is a self propelled wheeled vehicle that does not operate on rails such as trains or trolleys.
Overhang - that potion of a transport vehicle which extends beyond the front or rear bumper.
Pavement - (road surface) is the durable surface material laid down on an area intended to sustain vehicular or foot traffic such as road or walkway.
Pedestrian - is a person traveling on foot, whether walking or running.
Prying tool - a tool that can be used to forcibly open a locked door/cover by applying leverage to the door/cover at one of its edges.
R.A.4136 - Land transportation and traffic code.
Refuge island - (pedestrian island) is a small section of pavement or sidewalk completely surrounded by asphalt or other road materials where pedestrian can stop before finishing crossing the road.
Right of way - the right of one vehicle or pedestrian to proceed in a lawful manner in preference to another vehicle or pedestrian approaching under such circumstances of direction, speed, and proximity as to give rise to danger of collision unless one grants precedence to the other.
Road - is a thoroughfare, route, or way on land between two places which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle.
Roadway - consists of a width of road on which a vehicle is not restricted by any physical barriers or separation to move laterally.
Road junction - is a location where vehicular traffic going in different directions can proceed in a controlled manner designed to minimize accidents.
Runabout - is type of circular intersection or junction in which road traffic is slowed and flows almost continuously in one direction around a central island to several exits into the various intersecting roads.
Skid marks - marks left on the road surface when the tire stops rotating, locks up and skids.
Speed limit - the maximum speed at which a vehicle may legally travel on a particular stretch of road.
Stellar pattern - A bull’s-eye-type fracture of the windshield when struck by a human or anthropomorphic head during a collision. Damage occurs in the form of a circular pattern, with cracks radiating from the center.
Stile - is a structure which provides people a passage through or over a fence or boundary via steps, ladder, or narrow gaps.
Submarining - action of the occupant sliding forward underneath the lap belt portion of the restraint system, with the lap belt webbing resting above the pelvic girdle.
Tint - a color that has been made lighter by the addition of white.
Tire impression - when a tire contacts a surface, it results in the transfer of the class characteristics of design and size and possibly of wear and individual characteristics of the tire.
Tire patch - that portion of the tire that rest on the road surface.It is oval shaped and has its longest axis along the normal direction of travel of the vehicle.When a vehicle is sliding sideways, the tire marks left on the road gets almost twice as wide as the tires turn sideways and the short axis is in the direction of travel that makes the tire marks.
Tire thread - part of a tire that contacts the road surface and contains a design.
Traffic - may consists of pedestrians,ridden or herded animals,vehicles, streetcars, and other conveyances, either singly or together, while using the public way for purposes of travel.
Traffic circle - is a type of intersection that has a generally circular central island.
Traffic collision - (traffic accident) occurs when a vehicle collides with another vehicle, pedestrian, animal, road debris, or other stationary obstruction such as a tree or utility pole.
Traffic engineering - is a branch of civil engineering that use engineering techniques to achieve the safe and efficient movement of people and goods on roadways.
Traffic light - (traffic signal) are signalling devices positioned at road intersections, pedestrian crossings, and other locations to control competing flows of traffic.
Traffic signs - (road signs) are signs erected at the side of roads to provide information to road users.
Trails - (byway) is a path with a rough beaten or dirt/stone surface used for travel.
Tumblehome - The curvature of a vehicle body inward toward the roof. This gives the vehicle a rounder look from the front and decreases aerodynamic drag.
VIN - vehicle identification number, the serial number that the car's manufacturer stamps on several motor vehicle parts (many of which are inaccessible) for the purpose of tracing and identifying car ownership.
Vulcanization - a irreversible process in which a rubber compound is heated under pressure resulting in a chemical change in its structure.
Walkway - is a composite or umbrella term for all engineered surfaces or structures which support the use of trails.
Related Readings: Traffic Operation and Accident Investigation
1. Traffic operation and Investigation Reviewer 1
2. Crime Detection Review Questions