Chapter objectives:

-                 understanding the importance of individual transport models in a wider context,

-                 knowledge of simulation software suitable for transport modeling,

-                 knowledge of transport-engineering instruments for transport modeling.

 

Time required to study the chapter: 6 hours

Interpretation:

 

Transport-engineering instruments for transport modeling

Transport modeling does not include only traffic modeling and simulation. There are a number of transport-engineering instruments (tools) which can be used for many activities. 

In summary, however, these tools can be divided into several groups:

·     planning and decision-making tools (these cover supportive tools to help with tracing communications, designing transport areas, economic assessment of constructions, environmental impacts, and others – e.g. software AutoTURN, AeroTurn, etc.);

·     tools for the transport demand analysis (mainly focused on the allocation of traffic load on a communication network based on the existing and proposed transport infrastructure and the relevant urban concept);

·     analytical computational tools (these include mostly supportive software packages facilitating otherwise complicated calculations and their output consists in, for example, designs of traffic lights at intersections where some of the more sophisticated products can find optimal alignment of signal plans - Highway Capacity Manual, Edip-Ka, etc.);

·     tools for optimizing traffic devices (most of these tools are designed to optimize signal programs of traffic lights at intersections, or to design shift lanes and width ratios at uncontrolled intersections),

·     traffic simulation tools (the most comprehensive solutions are focused not only on the analysis and optimization of transport systems, but also provide a visual presentation of outputs – software VISSIM, Paramics, Aimsun NG, etc.).

 

Modeling and simulation of traffic flow

Transport (traffic) modeling and simulation is used mainly within transport engineering and transport planning. The aim is to create such a transport model in the given territory which can help apply transport infrastructure design (geometric and broad arrangement of the communication network), public passenger transport design (establishing new bus lines, stops locations, etc.) or environmental impact assessment.

The fundamental aspect of transport models is to model, as closely as possible, the vehicles movements and their mutual interactions. The main criteria include: the model network extent, the degree of approximation to the real state and the details illustration.

 

According to these criteria, models can be divided into:

·         macrosimulation models,

·         mesosimulation models,

·         microsimulation models,

·         nanosimulation models.

 

Microscopic simulation models

The principle of microscopic simulation (microsimulation) is to model the journeys of individual vehicles over a given communication network when taking into account all the parameters of an infrastructure and means of transport including the driver behavior. The basis of microscopic models is especially to model each vehicle movements moving in the traffic flow.

 

„Car following“ model

Car following model, which describes the longitudinal movement and behavior of the vehicle in the traffic flow depending on the previous vehicle, represents the most widespread type of microscopic simulation models.

The basic principle of the car following model is to determine the dependence of vehicle acceleration on surrounding conditions, which means, in a simpler case, only on a condition of a vehicle in front of a followed vehicle.

 

Study materials:

Basic literature:

Voženílek, V., Strakoš, V. City Logistics: Dopravní problémy města a logistika. Olomouc: Publisher - Palacky University, 2009, pp. 63-74. ISBN 978-80-244-2317-3

Electronic study support FAST VSB for the course “Modeling of transport on the road”, Available at (online): http://projekt150.ha-vel.cz/node/95

 

Questions and tasks

1.      Transport-engineering instruments for transport modeling do not include:

a)      tools for optimizing traffic devices

b)      three-phases simulation tools

c)      traffic simulation tools

2.      Planning and decision-making tools do not include:

a)      AutoTURN

b)      VISSIM

c)      AeroTurn

3.      Tools for the transport demand analysis are focused on:

a)      allocation of traffic load on a communication network

b)      modeling journeys of individual vehicles over a given communication network

c)      a visual presentation of outputs from simulations

4.      Models of traffic flow do not include:

a)      mesosimulation models,

b)      nanosimulation models

c)      analytical computational tools

5.      Define the “car following” model.

 

Key to solve the questions:

 

1)      b.

2)      b.

3)      a.

4)      c.

  5)   It describes the longitudinal movement and behavior of the vehicle in the traffic flow depending on the previous vehicle