Pre Midterm Content

Question 1

Describe the functional classifications of roads and their differences

Answer 1

Arterial: longest distance, few access points, highest speed limits
Collector: medium distance, medium access points, medium speed limits
Local: shortest distance, many access points, lowest speed limit
Freeways: do not provide access to fronting properties, entry and exit are strictly controlled

Question 2

What does the arterial classification prioritize

Answer 2

Mobility over access

Question 3

What does the local classification prioritize

Answer 3

Access over mobility

Question 4

What is the minimum design vehicle

Answer 4

The largest vehicle expected for routine use whose dimensions and
turning capabilities ought to be comfortably accommodated

Question 5

What are some types of medians and their purpose

Answer 5

Two-way left turn: accommodates speed turns + left and u-turning vehicles
Nonrased: provides an area for an out-of-control car + supports future growth
Landscaped: pretty and good for the environment but hard to maintain

Question 6

What is the purpose of a shoulder

Answer 6

Safe area for disabled vehicles
Enhances sight distance

Question 7

What is sight distance

Answer 7

Distance along the roadway that’s visible to a cyclist, motorist, or pedestrian

Question 8

What are the four aspects of sight distance

Answer 8

Stopping SD
Decision SD
Passing SD
Intersection SD

Question 9

What do macroscopic traffic flow models show

Answer 9

Aggregated and averaged characteristics of the traffic

Question 10

What do microscopic traffic flow models show

Answer 10

Behaviour of each individual vehicle in the system

Question 11

What do mesoscopic traffic flow models show

Answer 11

Mid-level analysis of traffic flow

Question 12

What do u, q, and k represent

Answer 12

Speed, flow, density

Question 13

What is time-mean speed in macroscopic analysis

Answer 13

Arithmetic mean speed of vehicles passing a fixed point over a specific time

Question 14

What is space-mean speed in macroscopic analysis

Answer 14

Average speed of vehicles over a specified distance

Question 15

Draw the speed density graph and identify the congested and noncongested area

Question 16

Explain the flow/speed/density relationship

Answer 16

Flow (q) = speed (u) * density (k)

Question 17

What happens to flow vs density after the critical density is reached

Answer 17

Flow starts to decrease

Question 18

Define intersection

Answer 18

At-grade crossing of two or more roadways

Question 19

Define approach

Answer 19

A lane or group of lanes through which vehicles enter the intersection

Question 20

Define lane group

Answer 20

An individual or multiple lanes grouped based on the allowed movement

Question 21

Define indication

Answer 21

Specific information or signal illumination by a traffic signal or control device

Question 22

Define phase

Answer 22

Defines which movements are allowed or restricted during a specific time period

Question 23

Define cycle

Answer 23

Complete sequence of signal indications

Question 24

Define ring

Answer 24

a sequence of movements that are not
compatible and must be timed sequentially.

Question 25

Define barrier

Answer 25

used to avoid operating conflicting movements at the same time. No movement on one side of the barrier can happen simultaneously with a movement on the other side of the barrie

Question 26

What are the four key design considerations in signalized intersection

Answer 26

Traffic flow characteristics Intersection geometric design Phasing and timing plans Pedestrian and safety assignments

Question 27

Define arrival flow

Answer 27

The number of vehicles or pedestrians per unit of time approaching the intersection during the design or evaluation period

Question 28

What adjustments are arrival flow subject to

Answer 28

Flow in vehicles per hour Flow in passenger car units per hour (must be adjusted into a homogenous unit)

Question 29

Define saturation flow

Answer 29

The rate at which queuing vehicles during red interval cross the stop line during the green interval

Question 30

What are some factors that can affect traffic

Answer 30

Grade road conditions transit stops parking pedestrians

Question 31

What are two approaches to obtaining saturation flow

Answer 31

Field observation Empirical estimation with adjustment factors

Question 32

What is the difference between field observation and empirical observation for obtaining saturation flow

Answer 32

Empirical estimation: dominant method Field observation: only for unique situations when it is anticipated that the saturation flow rate will be significantly different from the study area

Question 33

Define the intergreen period

Answer 33

The time between the end of green interval and beginning of earliest green interval for the next phase in the same signal cycle

Question 35

What is critical flow ratio

Question 36

What is intersection flow ratio

Answer 36

Sum of all critical flow ratios for all phases

Question 37

Define cycle length calculation

Answer 37

Summation of green phases and intergreen periods

Question 38

What are the two steps in calculating green time

Question 39

What is the clear zone

Answer 39

The unobstructed traversable area adjacent to the travel lanes (shoulder plus other stuff)

Question 40

What is super elevation

Answer 40

Angled banks that help with sharp curves traversed at high speeds