Week 5

Question 1

What are the three main types of traffic simulation models?

Answer 1

The three main types are:
1.
Macroscopic models: Simulate traffic flow as a fluid, focusing on aggregate characteristics like volume and density rather than individual agents.
Examples include the BPR function and the velocity-density model.
2.
Microscopic models: Simulate the behavior of individual agents (vehicles, pedestrians, etc.), including their interactions with each other and their environment. Examples include car-following models, lane-changing models, and gap acceptance models.
3.
Mesoscopic models: Combine elements of both macroscopic and microscopic approaches, offering a balance between detail and computational efficiency.

Question 2

The three components to microscopic simulation

Answer 2

Individual Vehicle Modelling: Each individual agent in
MICRO reacts on their current environment, i.e. the
distances and speed differences to nearby agents.
o Driving Behavior: Varied driver behaviors and decision-
making processes, which influence how vehicles interact and
maneuver.
o Inter-Vehicle Interactions: Detailed interactions between
vehicles are simulated, e.g., headways (distance or time
between vehicles), overtaking, and merging

Question 3

What level is a BPR function?

Answer 3

The Bureau of Public Roads (BPR) function, also known as the volume-delay function, is a macroscopic model that estimates travel time as a function of traffic volume. It assumes that travel time increases as traffic volume approaches the capacity of the road.

Question 4

What is the velocity-density model?

Answer 4

The velocity-density model is a macroscopic model that describes the relationship between traffic speed and density. It assumes that traffic speed decreases as density increases.

Question 5

Driving behaviour models can be divided into three categories:

Answer 5

Strategic-level model :
The road network as a
description unit, e.g.,
path selection

Tactical-level model:
The road as a
description unit, e.g.,
lane-changing, ramp
metering

Operational-level model:
The lane as a
description unit, e.g.,
car-following, brake
Driving behaviour models can be divided into three categories:

Question 6

Name two common car-following models

Answer 6

●
Pipes car-following model: Based on the rule that drivers should increase their following distance by at least one car length for every additional 10 mph of speed.
●
Forbes car-following model: Incorporates the driver’s reaction time into the car-following behavior, emphasizing that the headway time (time gap between vehicles) should be greater than or equal to the driver’s reaction time.

Question 7

what level is Driving behaviour models

Answer 7

Micro

Question 8

What is VISSIM?

Answer 8

VISSIM is a microscopic traffic simulation software developed by PTV. It is widely used for analyzing and optimizing traffic flow in various transportation systems.

Question 9

What is the travel demand model?

Answer 9

The travel demand model is a set of mathematical relationships used to understand and predict travel patterns within a geographic area. It aims to answer questions like:
●
How many trips are generated?
●
Where are these trips going (origin and destination)?
●
What modes of transport are used?
●
Which routes are chosen?