HIGHWAY ASSESSMENT2
Measures that describe the traffic stream as a whole, such as flow, average speed, and density, are referred to as ______
Macroscopic measures
Time headway and spacing are referred to as ______ because they describe characteristics specific to individual pairs of vehicles within the traffic stream
Microscopic measures
The time between the passage of the front bumpers of successive vehicles, at some designated highway point, is known as the ______
Time headway
_____ is often measured over the course of an hour, in which case the resulting value is typically referred to as volume
Flow
Traffic streams that operate under the influence of signals and stop signs are classified as ____
Interrupted flow
An observer counts A trafic stream that operates free from the infuence of such trafic control devices as signals and stop signs is classifed as ____
Uninterrupted flow
This is an example of a model that account for the nonuniformity of flow are derived by assuming that the pattern of vehicle arrivals (at a specified point) corresponds to some random process
Poisson Model
As more and more vehicles begin to use a section of highway, the traffic density will increase, and the average operating speed of vehicles will decline from the free-flow value as drivers slow to allow for the maneuvers of other vehicles. Eventually, the highway section will become so congested. This high-density condition is referred to as the _____
Jam density
This is the arithmetic mean of the vehicle speeds observed at some designated point along the roadway
Time mean speed
This speed is determined on the basis of the time necessary for a vehicle to travel some known length of roadway
Space-mean speed
Under be very low density, and the driver will be able to travel freely at a speed close to the design speed of the highway. This speed is referred to as the _____
Free-flow speed
Under jam density, you can freely choose your speed of travel
False
Space-mean speed will always be lower than the time-mean speed, unless all vehicles are traveling at exactly the same speed
True
An observer counts 354 veh/h at a specific highway location. Assuming that the arrival of vehicles at this highway location is Poisson distributed, estimate the probabilities of having 4 vehicles arriving over a 11-second time interval
0.0193
The speeds of five vehicles were measured (with radar) at the midpoint of a 0.7-mile section of roadway. The speeds for vehicles 1, 2, 3, 4, and 5 were 16, 20, 23, 25, 30 and mi/h, respectively. Assuming that all vehicles were traveling at constant speed over this roadway section, calculate the space-mean speed
21.8
The speeds of five vehicles were measured (with radar) at the midpoint of a 0.9-mile section of roadway. The speeds for vehicles 1, 2, 3, 4, and 5 were 16, 19, 22, 27, 30 and mi/h, respectively. Assuming that all vehicles were traveling at constant speed over this roadway section, calculate the time-mean speed
22.8
Vehicle time headways and spacings were measured at a point along a highway, from a single lane, over the course of an hour. The average values were calculated as 3.3 s/veh for headway and 216 ft/veh for spacing. Calculate the average speed of the traffic
44.6281