問題一覧
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They provide the basic information necessary for meaningful planning, design and analysis of highways and other road transportation infrastructures.
Traffic studies
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are conducted to determine the number, movements, and classifications of roadway vehicles at a given location.
Volume studies
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AADT
Average anual daily traffic
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ADT
Average daily traffic
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PHV
Peah hour volume
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VC
Vehicle classification
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VMT
Vehicle miles of travel
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is the average 24-hour counts collected every day in the year.
Average anual daily traffic
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the average 24-hour counts collected over a number of days greater than 1 but less than a year.
Average daily traffic
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maximum number of vehicles that pass a point on a highway during a period of 60 consecutive minutes
Peak hour volume
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records volume with respect to the type of vehicles, for example, passenger cars, two-axle trucks, or three-axle trucks.
Vehicle classification
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measure of travel along a section of road.
Vehicle miles of travel
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used for evaluating capacity deficiencies, geometric design or improvement of streets and intersections.
Hourly Traffic
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is used to estimate maximum flow rate and determine the characteristics of peak hour volumes
Short term count
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Types of Data Collected:
Mid-block counts Directional counts Intersection counts Classification counts Cordon counts
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used for preparing traffic flow maps and determining trends.
Mid-block counts
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used for determining directional distribution for capacity analysis, signal timing, justifying traffic control, etc.
Directional counts
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are used for signal timing, designing or improving geometry of intersections, planning turning prohibition, analyzing high accident intersections.
Intersection counts
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used for determining modal split, estimating effects of heavy vehicles on capacity, determining correction factors for automatic counts.
Classification counts
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used to determine the number of vehicles and/or persons entering or leaving an enclosed area
Cordon counts
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Considered as the simplest and sometimes the most practical in the absence of any mechanical or automatic counting devices.
Tallying
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a mechanical device useful when volume is high. Counters may be of single or multiple type.
Manual counters
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When traffic count of very long duration is required, one may resort to automatic counters through the use of detectors.
Automatic counters
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When traffic count of very long duration is required, one may resort Video cameras may be used to take footage of the traffic flow. Counts may then be carried out later through either tally or manual method while watching the video
Video cameras
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Presentation of traffuc volume
Variation Flow maps intersection diagram
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Spot sleep studies
Road detectors Radar-based traffic sensors Electronic-princple detectors
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Methods for Conducting Spot Speed Studies
Video taping Road Detectors Doppler Radar meter
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three intersection design categories
graded seperate without ramps graded seperate with ramps at grade
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circular intersection that provides a circular traffic pattern with significant reduction in the crossing conflict points.
traffic circle
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have large diameters that are usually greater than 300 ft, thereby allowing speeds exceeding 30 mi/h, with a minimum horizontal deflection of the path of the through traffic.
Rotaries
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diameters that are much smaller than rotaries and therefore allow much lower speeds.
neighborhood traffic circle
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a defined area between traffic lanes that is used to regulate the movement of vehicles or to serve as a pedestrian refuge.
island traffic