traffic engineering: traffic characteristics Flashcards
(117 cards)
1
Q
What are the 3 main categories of traffic studies?
A
- inventories
- administrative studies
- dynamic studies
2
Q
_____ provide a list or graphic display of existing information, such as street widths, parking spaces, transit routes, traffic regulations, adn so forth.
A
inventories
2
Q
____ use existing engineering records, available in government agencies and departments.
A
administrative studies
3
Q
____ include the results of surveys, which may involve field measurements and/or aerial photogrpahy.
A
administrative studies
4
Q
____ involve the collection of data under operational conditions and include studies of speed, traffic volume, travel time and delay, parking, and crashes.
A
dynamic studies
5
Q
What are the 4 studies under dynamic traffic studies?
A
- spot speed studies
- volume studies
- travel time and delay studies
- parking studies
6
Q
_____ are conducted to estimate the distribution of speeds of vehicles in a stream of traffic at a particular location on a highway.
A
spot speed studies
7
Q
The ____ is defined as the rate of movement of the vehicle.
A
speed of the vehicle
8
Q
A ____ is carried out by recording the speeds of a sample vehicle at a specified location.
A
spot speed study
9
Q
Speed limits (___th-percentile speeds is commonly used as the speed limit on the road).
A
85
10
Q
What are the 3 locations for spot speed studies?
A
- locations that represent different traffic conditions (basic data collection)
- mid-blocks of urban highways and straight (speed trend analysis)
- any location (specific traffic engineering problem)
11
Q
The time of day for conducting a speed study depends on the _____.
A
purpose of the study
12
Q
To establish posted speed limits, to observe speed trends, or to collect basic data – conduct study when
A
traffic is free-flowing usually during off-peak hours
13
Q
Conducted in response to citizen complaints, it is useful if the time period selected for the study _____
A
reflects the nature of the complaints
14
Q
Typically, the duration is at least ___ and the sample sample size is at least ___ vehicles.
A
1 hour, 30
15
Q
The ____ (or average) speed is used to represent the true mean value of all vehicle speeds at that location.
A
calculated mean
16
Q
The larger the sample size (number of vehicles), the ____ the probability that the estimated mean is not significantly different from the true mean.
A
greater
17
Q
____ are used to determine this minimum sample size.
A
statistical procedures
18
Q
What are the 6 significant values needed to described speed charactersitcs?
A
- average speed
- median speed
- modal speed
- the ith-percentile spot speed
- pace
- standard deviation of speeds
19
Q
____ is the arithmetic mean of all observed vehicle speeds (which is the sum of all spot speeds divided by the number of recorded speeds).
A
average speeds
20
Q
____ which is the range of speed–usually taken at 10-mi/h intervals–that has the greatest number of observations.
A
pace
21
Q
____ which is a measure of the spread of the individual speds.
A
standard deviation of speeds
22
Q
What are the 2 main categories of conducting spot speed studies?
A
- manual
- automatic
23
Q
What are the 3 manual devices?
A
- stopwatch
- radar gun
- lidar gun
24
What are the 3 automatic devices?
1. those that use road detectors (pneumatic road tubes, inductive loop)
2. those that are radar-based (radar recorders)
3. those that use the principles of electronics (autoscope)
25
____ is wireless detector with a single camera that can replace many loops, thereby providing a wide-area detection system.
autoscope
26
____ work on the principle that when a signal is transmitted onto a moving vehicle, the change in frequency between the transmitted signal and the reflected signal is proportional to the speed of the moving vehicle.
radar recorders
27
____ laid across the lane
pneumatic road tube
28
____ are conducted to collect data on the number of vehicles and/or pedestrians that pass a point on a highway facility during a specified time period.
traffic volume studies
29
Traffic volume studies time period varied from as little as ____ to as much as ___ depending on the anticipated use of the data.
15 minutes - 1 year
30
The data collected from traffic volume studies may also be put into 4 subclasses:
1. directional movement
2. occupancy rates
3. vehicle classification
4. pedestrian age
31
____ are usually conducted when certain volume characteristics are needed.
traffic volume studies
32
What are the 5 volume characteristics?
1. average annual daily traffic (AADT)
2. average daily traffic (ADT)
3. peak hour volume (PHV)
4. vehicle classification (VC)
5. vehicle miles of travel (VMT)
33
_____ is the average of 24-hour counts collected every day of the year.
average annual daily traffic (AADT)
34
__ is the average of 24-hour counts collected over a number of days greater than one but less than a year.
average daily traffic (ADT)
35
What are the 3 which ADT may be used for?
1. planning of highway activities
2. measurement of current demand
3. evaluation of existing traffic flow
36
___ is the maximum number of vehicles that pass a point on a highway during a period of 60 consecutive minutes.
peak hour volume (PHV)
37
____ records volume with respect to the type of vehicles, for example, passenger cars, two-axle trucks, or three-axle trucks.
vehicle classification (VC)
38
____ is a measure of travel along a section of road.
vehicle miles of travel (VMT)
39
____ is the product of the traffic volume (that is, average weekday volume or ADT) and the length of raodway in miles to which the volume is applicable.
vehicle miles of travel (VMT)
40
____ are used mainly as a base for allocating resources for maintenance and improvement of highways.
VMT
41
What are the 2 methods of conducting volume count?
1. manual method
2. automatic method
42
___ involves one or more persons recording observed vehicles using a counter.
manual counting
43
With the manual counting method, both the ____ at the intersection and the ___ can be recorded.
turning movement, types of vehicles
44
What are the 3 main disadvantages of the manual count method?
1. labor intensive; thus expensive
2. subject to the limitations of human factors
3. cannot be used for long periods of counting
45
What are the 2 categories of automatic counters?
1. require the laying detectors (surface or subsurface)
2. do not require the laying of detectors
46
Automatic counters that ____ (such as pneumatic road tubes) or subsurface detectors (non-invasive, such as magnetic or electric contact devices) on the road, detect te passing vehicle and transmit the information to a recorder, which is connected to the detector at the side of the road.
require the lying of surface detectors
47
What are the 5 types of volume counts?
1. cordon counts
2. screen line counts
3. intersection counts
4. pedestrian volume counts
5. periodic volume counts
48
What are the 3 types under the periodic volume counts?
1. continuous counts
2. control counts
3. coverage counts
49
When information is required on vehicle accumulation within an area such as the central business district (CBD) of a city, particularly during a specific time, a ____ is undertaken.
cordon count
50
The area for which the data are required is cordoned off by an imaginary closed loop; the are enclosed within this loop is defined as the _____.
cordon area.
51
In _____, the study area is divided into large sections by running imaginary lines, known as screen lines, across it.
screen line counts
52
In some cases, ______, such as rivers or railway tracks, are used as screen lines.
natural and manmade barriers
53
____ are taken to determine vehicle classifications, through movements, and turning movements at intersections.
intersection counts
54
____ data are used mainly in determining phase lengths and cycle times for signalized intersections, in the design of channelization at intersections, and in the general design of improvements to intersections.
intersection counts
55
_____ are made at locations such as subway stations, midblocks, and crosswalks.
volume counts of pedestrians
56
___ counts can be used for crash analysis, capacity analysis, and determining minimum signal timings at signalized intersections.
pedestrian volume counts
57
_____ are taken continuously using mechanical or electronic counters.
continuous counts
58
Stations at which continuous counts are taken are known as _____.
permanent count stations
59
A ____ is defined for traffic count purposes as a homogeneous section that has the same traffic characteristics, such as AADT and daily, weekly, and seasonal varioations in traffic volumes at each point.
highway link
60
What are the 3 broad classification systems for major roads?
1. freeways
2. expressways
3. major arterials
61
What are the 3 broad classification systems for minor roads?
1. residential
2. commercial
3. industrial
62
Control counts are taken at stations known as ____, which are strategically located so that representative samples of traffic volume can be taken on each type of highway or street in an area-wide traffic counting program.
control-count stations
63
The data obtained from ____ are used to determine seasonal and monthly variations of traffic characteristics so that expansion factors can be determined.
control counts
64
Control counts can be divided into 2:
1. major counts
2. minor counts
65
____ are taken monthly, with 24-hour directional counts taken on at least three days during the week (Tuesday, Wednesday, and Thursday) and also on Saturday and Sunday to obtain information on weekend volumes.
major control counts
66
____ are five-day weekday counts taken every other month on minor roads.
minor control counts
67
____ counts are used to estimate ADT, using expansion factors developed from control counts.
coverage counts
68
A 24-hours non-directional weekday counts is taken at least once every four years at each coverage station.
coverage counts
69
A _____ study determines the amount of time required to travel from one point to another on a given route.
travel time study
70
Data obtained from ____ given a good indication of the level of service on the study section.
time and delay studies
71
____ is the time taken by a vehicle to traverse a given section of a highway.
travel time
72
_____ is the time a vehicle is actually in motion while traversing a given section of a highway.
running time
73
___ is the time lost by a vehicle due to causes beyond the control of the driver.
delay
74
____ is that part of the delay caused by the impedance of other traffic.
operational delay
75
_____ where the stream flow is interfered with by other traffic (for example, parking or unparking vehicles)
side friction
76
___, where the interference is within the traffic stream (for example, reduction in capacity of the highway).
internal friction
77
____ is that part of the delay caused by control devices such aas traffic signals.
fixed delay
78
____ delay occurs regardless of the traffic volume or the impedance that may exist.
fixed delay
79
_____ is the difference between the actual travel time and the travel time that will be obtained by assuming that a vehicle traverses the study section at an average speed equal to that for an uncongested traffic flow on the section being studied.
travel-time delay
80
What are the 2 general categories of methods for conducting travel time and delay studies?
1. those using a test vehicle
2. those not requiring a test vehicle
81
What are the 3 possible techniques of methods requiring a test vehicle?
1. floating-car technique
2. average-speed technique
3. moving-vehicle technique
82
____, the test car is driven by an observer along the test section so that the test car "floats" with the traffic.
floating-car technique
83
The driver of the test vehicle attempts to pass as many vehicles as those that pass his test vehicle.
floating-car technique
84
____ involves driving the test car along the length of the test section at a speed that, in the opinion of the driver, is the average speed of the traffic stream.
average-speed technique
85
____, the observer makes a round trip on a test section like the one shown in Figure 4.16, where it is assumed that the road runs to east to west.
moving-vehicle technique
86
What are the 2 methods not requiring a test?
1. license-plate observations
2. interviews
87
The ____ requires that observers be positioned at the beginning and end of the test section.
license-plate method
88
Each observer records the last three or four digits of the license plate of each car that passes, together with the time at which the car passes.
license-plate observations
89
The ____ is carried out by obtaining information from people who drive on the study site regarding their travel time, their experience of delays, and so forth.
interviewing method
90
____ facilitate the collection of a large amount of data in a relatively short time.
interviews
91
____ are used to determine the demand for and the supply of parking facilitates in an area, the projection of the demand, and the views of various interest groups on how best to solve the problem.
parking studies
92
What are the 2 types of parking facilities?
1. on-street parking facilities
2. off-street parking facilities
93
___ are known as curb facilities.
on-street parking facilities
94
____ are provided alongside the curb on one or both sides of the street.
parking bays
95
____ facilities may be privately or publicly owned; they include surface lots and garages.
off-street parking facilities
96
____ require that drivers park their own automobiles attendant-parking garages maintain personnel to park the automobiles.
self-parking garages
97
A ___ is a unit of parking that defines the use of a single parking space for a period of 1 hour.
space-hour
98
___ is the total number of vehicles that park in a study area during a specific length of time, usually a day.
parking volume
99
___ is the number of parked vehicles in a study area at any specified time.
parking accumulation
100
The ___ is the area under the accumulation curve between two specific times.
parking load
101
___ is usually given as the number of space-hours used during the specified period of time.
parking load
102
___ is the length of time a vehicle is parked at a parking bay.
parking duration
103
____ is the rate of use of a parking space.
parking turnover
104
___ is obtained by dividing the parking volume for a specified period by the number of parking spaces.
parking turnover
105
The ___ includes both on- and off-street facilities.
inventory
106
The information obtained from an ___ is useful both to the traffic engineer and to public agencies, such as zoning commissions and planning departments.
inventory of parking facilities
107
The inventory should be updated at regular intervals of about _____.
4 to 5 years
108
____ are obtained by checking the amount of parking during regular intervals on different days of the week.
accumulation data
109
The checks are usually carried out on an hourly or 2-hour basis between ____ and ____.
6:00 am and 12:00 midnight
110
Information on ____ is usually obtained by collecting data on a sample of parking spaces in a given block.
turnover and duration
111
The length of the fixed intervals depends on the ____.
maximum permissible duration
112
What are the 2 under collection of parking data?
1. identification of parking generators
2. parking demand
113
____ phase involves identifying parking generators (for example, shopping centers or transit terminals) and locating these on a map of the study area.
identification of parking generators
114
Information on ___ is obtained by interviewing drivers at the various parking facilities listed during the inventory.
parking demad
115
An effort should be made to interview all drivers using the parking facilities on a typical weekday between ______ and ___. (parking demand)
8:00 am anf 10:00 pm
116
What are the 3 information sought during the interview for parking demand?
1. trip origin
2. purpose of trip
3. driver's destination after parking
