Midterm 2 exam - CIV E481
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Moorpark College *
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CIVE481
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Aerospace Engineering
Date
Apr 3, 2024
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docx
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Uploaded by MinisterElement622
Midterm 2 exam - CIV E481 True or False
1.
______ The
space-mean
speed is more useful for traffic analysis than the
time-mean
speed
2.
______ Headway is a measure of distance
between successive vehicles 3.
______ The speed-flow model is a
linear relationship 4.
______ The Flow-Density model is a linear relationship 5.
______ Speed = 0 at jam density (
K
j
¿
6.
______ Maximum flow occurs at maximum speed (
u
f
)
7.
______ The Poisson model is used to simulate a random traffic arrival pattern
8.
______ The Poisson model is used to simulate a uniform or deterministic traffic arrival pattern 9.
______ LOS A represents free-flow traffic conditions 10. ______ LOS C describes a complete breakdown in vehicular flow 11. ______ LOS D describes a complete breakdown in vehicular flow 12. ______ For LOS determination, two-lane highways only need to consider traffic in one direction
13. ______ Base conditions for a basic Freeway segment include 12-ft lane widths and level terrain 14. ______ Base conditions for a Basic Freeway Segment include 11-ft lane widths and rolling terrain
15. ______ Free flow speed (FFS) for freeways is subject to adjustment by lane width, lateral clearance, median type, and number of access points
16. ______ Free flow speed (FFS) for freeways is subject to adjustment by lane width, lateral clearance, and ramp density
17. ______ Multilane highways may include traffic signals and are not always divided (by barrier or median)
18. ______ Multilane highways are always divided (by a barrier or a median), just like Freeways.
Answers:
1)
True -
Space-mean speed accounts for slower vehicles more heavily as they hold the road longer. Due to this reason, In many traffic equations, space-mean speed is preferred over time-
mean speed.
2)
False - Headway is classified into 2 types, distance and time. The distance headway is the gap between the bumper to the bumper of the lead vehicle and the following vehicle and it is expressed in distance units. The time headway is the time interval between two vehicles, calculated as the distance between the vehicles divided by the speed of the following vehicle.
3)
False -
The speed flow model is not linear as any given flow can have two different speeds.
4)
False
- The flow density model has a parabolic relationship between flow and density and the green shield model assumes a linear relationship between flow & density.
5)
True - Speed is typically zero at jam density, representing the point of maximum congestion.
6)
False - Maximum flow occurs at an intermediate speed, not necessarily at maximum speed. Traffic flow is expressed as vehicles per hour. At maximum flow, the speed will be between zero and free-flow speed. 7)
True - The Poisson model is used for random traffic arrival 8)
False -
The Poisson model doesn't represent a uniform or deterministic traffic arrival pattern.
9)
False -
LOS A means vehicles are almost completely unimpeded in their ability to maneuver within the traffic stream, passing demand is well below passing capacity, and drivers are delayed no more than 30 percent of the time by slow-moving vehicles.
10)
False - LOS C represents conditions where traffic flows at near Free-Flow Speed. The breakdown of vehicular traffic is represented by LOS F. LOS F is the level of service that describes a complete breakdown in vehicular flow
11)
False-
LOS D does not describe a complete breakdown in vehicular flow, but rather a condition where traffic flow is considered "unstable" or "approaching unstable."
12)
False - Unlike Freeways, two-lane highways must consider traffic in both directions to find LOS because traffic in opposite directions influences the level of traffic of service. 13)
True -
Base conditions for a basic Freeway segment include 12-ft lane widths
14)
False - 15)
False
-?
16)
True - FFS is calculated from BFFS after adjustments due to lane width (flw), lateral clearance (flc), number of lanes in each direction (fn), and ramp density(fid)
17)
True - Multilane highways may be divided or undivided 18)
False - Multilane highways may be divided or undivided but Freeways are always divided
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