TEST 1

Question 1

When considering hte amount of time it takes to go from origin to a desitinatio, the total travel time can be divided into these two categories:

Answer 1

In vehicle travel time

Out of vehicle travel time

Question 2

Transport Facilities provide these two distinct function:

Answer 2

1) Land access
2) Movement (mobility)

Question 3

Explain why redundancies in a transporation system can be a good thing.

Answer 3

Redundancies in a transporation system can increase reliability by providing duplications of critical facilities. If one part of the system fails (e.g. traffic crash closes a road), then another part (i.e. the reundant one) can help make up for it & prevent system failure.

Question 4

Explain why reduncies in a transportation sytem can also be a bad thing.

Answer 4

Too much dedundancies can be prohibitevely expensive to build & maintain. Further, in a transportation system, more redundancies may mean a greater proportion of land being used for transport instead of other productive uses.

Question 5

In a mode choice model, a decision maker n is assumed to choose between i alternatives. How many attributes can be used in such a model to describe each alternative?

Answer 5

As many as can be measured.

Question 6

In one route choice model, users of a transportation system are assumed to use he route with the shortest travel time for their trips. What is the definition of equilibrium for the static approach in considering route choice in a such a model?

Answer 6

Equilirbium is the state in which the travllers on all routes between two places expereince the same travel time.

Question 7

What is an example of changing the supply?

Answer 7

Changing the supply can be changing the capacity, which may include widening/ narrowing a road, adding/ subtracting bus service, building/ digging up sidewalks, using bigger/smaller planes, etc.

Question 8

What is an exampe of chaning the demand?

Answer 8

Too much redundancies can be prohibitively expensive to build & maintain. Further, in transportation system, more redundancies may mean a greater proportion of land being used for transport instead of other productive uses.

Question 9

In calculating traffic signal timing, “Lost Time” accounts for two things. What are they?

Answer 9

Start up of vehicles and clearance of intersection

Question 10

In general, does increasing the number of phases in a traffic signal plan increase, decease, or have no effets on the traffic flow efficiency of an intersection?

Answer 10

decrease

Question 11

What is “headway” and what are its appropriate units?

Answer 11

Headway is the separation in time between two ro more consecutive vehicles measured from similar locations (e.g. front bumpers) of the vehicles units = time (seconds) per vehicle

Question 12

When conducting counts of motor vehicle traffic, why is it important to count passenger cars, trucks, and buses separetely?

Answer 12

Passenger cars, trucked & buses are different in size & they may behave differently (e.g. different speeds, acceleration/decceleration)

Question 13

How many critical lane groups are there for each phase of a traffic signal plan?

Answer 13

1

Question 14

When considering a set of lane groups, the critical lane group alwas has the highest value of what?

Answer 14

Volume/saturation flow rate (v/s)

Question 15

What does “Peak Hour Factor (PHF)” Represent?

Answer 15

PHF represents the distribution of traffic flow over an hour. It is 1 when there’s no fluctuations & 0.25 if there’s extreme peaking

Question 16

Is “Time Mean Speed” calculated using data measured at a point or section

Answer 16

Point

Question 17

Can “Time Mean Speed” be greater than “Space Mean Speed?”

Answer 17

YES (THS >= SMS)

Question 18

The Poisson Model of vehicle arrival has two important assumptions. What are they?

Answer 18

1) Arrival of each vehicle is independent
2) flow rate over a short period of time is constant

Question 19

We have discussed tranportation systems and their components in terms of six “Critical ussues” What are they?

Answer 19

Safety, Congestion (efficiency), Infrastructure, Finance, Equity, Energy / Environment

Question 20

What are “Traffic control warrants” designed to do?

Answer 20

They are designed to evaluate how an intersection is operating and whether certain controls (e.g. stop signs, traffic signals) are needed

Question 21

Can the cycle length of a 2 phase traffic signal be longer than a 3 phase traffic signal?

Answer 21

YES

Question 22

What is the “Saturation flow” of an approach?

Answer 22

It is the maximum flow possible through an intersection for a movement from an approach if that approach has all of the green time allocated.

Question 23

Difference between a “Protected Movement” and a “Permitted Movement”

Answer 23

A protected movement has the right of way

A permitted movement must yield first

Question 24

In traffic flow, what is the difference between “headway” and “gap”?

Answer 24

Headway is the separation in time or space between 2 consecutive vehicles usignt he same reference point (e.g. front to front)

Gap is the separation in time or space from the rear of one vehicle to the front of the next vehicle.

Question 25

What is the foundational assumption of the Greenshields Model?

Answer 25

The speed - density relationship is linear