TRANSPO - BESA
It is defined as the number of vehicles per unit distance occupying a section of roadway at a given instant time and is usually measured in vehicles per mile or per km
Density
The number of vehicles moving in a specified direction on a given lane or roadway that pass a given point during specified unit time and is usually expressed as vehicles per hour or vehicles per day.
Traffic volume
The ability of a roadway to accommodate traffic volume. It is expressed as the maximum number of vehicle in a lane or a road that can pass a given point in unit time, usually an hour, that is vehicles per hour per lane or roadway.
Traffic capacity
The max. number of passenger cars that can pass a given point on a lane or roadway during one hour under the most nearly ideal roadway and traffic conditions which can possibly be attained.
Basic capacity
The max. number of passenger cars that can pass a given point on a lane or roadway during one hour under prevailing roadway and traffic conditions.
Possible capacity
The max. number of vehicles that can pass a given point on a lane or roadway during one hour without traffic density being so great as to cause unreasonable delay, hazard, or restrictions to the driver's freedom to maneuver under the prevailing roadway and traffic conditions.
Practical capacity
The crossing of two or more traffic streams traveling in the same general direction along a signific signath.
Weaving
The instantaneous speed of a vehicle at a specified section or location.
Spot speed
The average of the spot speeds of all vehicles passing a given point in the highway.
Average speed
The average speed of vehicles in a certain road length at any time.
Space mean speed
The speed distribution of vehicles at a point on the roadway and it is the average of instantaneous speeds of observed
vehicles at the spot.
Time-mean speed
The average speed maintained by a vehicle over a particular stretched of road, while the vehicle is in motion. This is obtained by dividing the distance covered by the time during which the vehicle is in. motion.
Running speed
The time interval between the passage of successive vehicles moving in the same lane and measured from head to head as they pass a point on the road.
Time headway
The distance between successive vehicles moving in the same lane measured from head to head at any instance.
Space-headway
The distance ahead that must be clear to permit safe passing is called:
Passing sight distance
The ratio between parallel forces divided by the normal forces is known as:
All of the above
Divided arterial highway for through traffic with full or partial control of access and generally with grade separations at major intersections.
Expressway
An expressway with full control of access.
Expressway
An arterial highway for non-commercial traffic with full or partial control of access and usually located within a park.
Parkway
Minimum sight distance required for a driver to stop a vehicle after seeing an object in the vehicle's path without hitting that object. This distance is the sum of the distance traveled during perception-reaction time and the distance traveled during braking.
Stopping sight distance
Minimum sight distance required on a two-lane, two-way highway that will permit a driver to complete a passing maneuver without colliding with an opposing vehicle and without cutting off the passed vehicle.
Passing sight distance
The length of super elevation development from zero cross slope to full design super elevation in a circular curve alignment.
Super elevation run off
The length of super elevation development from the normal cross slope to the zero cross slope point on the tangent.
Tangent run out
The location super elevation development onto circular curves has been continuous concern to designers throughout the world. This concern is due to the fact that design super elevation is not available for the curve radius at the P.C. This results in the vehicle experiencing 2 to 3 sec. where lateral acceleration tends to force the driver to adopt a natural spiral curve during entry and exit. This problem can be prevented by:
Provide a proportion of super elevation run off. This proportion tends to minimize the adverse effects of lateral acceleration and improves the safety of the transition from tangent to circularcurve.
The longitudinal profile along the centerline of the road. It is made up of a series of grades and vertical curves.
Vertical alignment
Time required for transmission of the sensations received (through eyes, ears and body) to the brain and the spinal chord by the nervous system, to a particular traffic situation.
Perception time
After perception occurs, the formation of new thoughts and ideas, recalling old memories of similar occasions to a particular traffic situation.
Intellection
The time linked with the two stages perception and intellection based on a particular traffic situattuence fear or anger which has a vital influence on the final message or decision sent by the brain to the muscle is called:
Emotion
The time of taking a decision to produce action to a particular traffic situation is called:
Volition time
The total time required for perception, intellection, emotion and volition that is from the instant the object comes in the line of sight of the driver to the instant he arrives a decision, say to slow down or overtake, under normal circumstances is called:
Reaction time
Distance traveled by the vehicle during the total reaction time.
Lag distance
Distance traveled by the vehicle after the application of the brakes until it will stop.
Braking distance
The basic traffic maneuvers:
I. Diverging
II. Merging
Ill. Crossing
IV. Weaving
I, Il and Ill only
When a vehicle moves obliquely across the path of another vehicle moving in the same direction, at relatively small angle of crossing, the action is termed as:
Weaving
The number of vehicle occupying a unit length of lane roadway at a given instant, usually expressed as vehicle per km.
Traffic density
The maximum sustained 15 min. rate of flow, expressed in passenger cars per hour per lane, which can be accommodated by a uniform freeway segment under prevailing traffic and roadway conditions in one direction.
Capacity
The maximum number of passenger cars that can pass a given point on a lane or roadway during one hour under the most nearly ideal roadway and traffic conditions which can possibly be attained.
Road capacity
The difference between the time the front of a vehicle arrives at a point on the highway and the time the front of the next vehicle arrives at the same point.
Time headway
The distance between the front of a vehicle and the front of the following vehicle.
Space headway
The arithmetic mean of the speeds of vehicles passing a point on a highway during an interval of time.
Time mean speed
The harmonic mean of the speed of vehicles passing a point on a highway during an interval of time. It is obtained by dividing the total distance traveled by two or more vehicles on a section of a highway by the total time required by these vehicles to travel that distance.
Space mean speed
The maximum speed that can be attained on a highway as the flow tends to zero.
Mean free speed
The process by which a vehicle in on traffic in the stream joins another traffic stream moving in the same direction such as a ramp vehicle joining a freeway stream.
Merging
The process by which a vehicle in a traffic stream leaves that traffic stream, such as a vehicle leaving the outside lane of an expressway.
Diverging
The process by which a vehicle first merges into a stream of traffic obliquely crosses that stream, then merges into a second stream moving in the same direction.
Weaving
The headway in a major stream, which is evaluated by a vehicle driver in a minor stream who wishes to merge into the major stream.
Gap
The difference between the time a vehicle that merges into a main traffic stream reaches a point on the highway in the area of merge and the time a vehicle in the main stream reaches the same point.
Time lag
The average of 24-hour traffic counts collected every day in the year. These counts are used to estimate highway user revenues, compute accident rates, and establish traffic volume trends.
Average Annual Daily Traffic (AADT)
The average of 24-hour traffic counts collected over a number of days greater than one but less than a year. These counts are used for planning of highway activities,
measuring current traffic demand and evaluating existing traffic flow.
Average Daily Traffic (ADT)
A measure of travel usage along a section of road. It is the product of the volume (ADT) and the length of roadway in miles to which the volume is applicable. This measure is used mainly as a base for allocating resources for maintenance and improvement of highways and to establish highway system usage trends.
Vehicle Miles of Travel (VMT)
The maximum number of vehicles that pass a point on a highway during a period of 60 consecutive minutes. This volume is used for functional classification of highways, geometric design standards selection, capacity analysis, development of operational programs, and development of parking regulations.
Peak Hour Volume (PHV)