00 - Intro to subject - TDBM

In this course we will study the UTP ([[Urban Transportation Planning]]) 4 stage framework:

[[#1 - Data Collection]]

[[#2 - Modeling]]
[[#3 - Forecasting]]
[[#4 - Evaluation]]

Classic 4 stage framework

The classic 4 stage framework is also called trip-based approach. This is because it relies trip as unit of analysis. This approach is described in the following paragraph but is becoming more and more limited in the ability to model people mobility as it cannot account for [[Intermodality]] (using more than one mode of transportation for one trip). Therefore, a new approach has been proposed and is gaining popularity: the [[#Activity-based modeling]]

1 - Data Collection

This is the first stage of the UTP 4 stage framework.

At this stage we need:

Socio-economic and land use data
Define zonizzazione)
Define transportation infrastrucure (network)

All the data that is available needs to be grouped by TAZ

2 - Modeling

In the modeling stage, we apply the a 4 steps modeling process modello a 4 stadi. This actually the union of 4 models that describe different aspects of transportation:

[[#I - Trip generation]]
[[#II - Trip Distribution]]
[[#III - Mode choice]]
[[#IV - Route choice]]

purpose

In the modeling stage we also need to account for the purpose of a trip. This is usually done through defining the 4 steps for each and every purpose.

So, for example, we will have Generation, Distribution, mode choice and route choice for school trips, for work trips, for leisure trips, etc.

The results of this modeling will go into an OD matrix (see matrici origine-destinazione). To be precise will go into a set of OD matrixes, one for each purpose.

\begin{matrix} d_{11} & d_{12} & \dots & d_{1 n} & P_{1} \\ d_{21} & d_{22} & \dots & d_{2 n} & P_{2} \\ ⋮ & ⋮ & d_{i j} & ⋮ & ⋮ \\ d_{n 1} & d_{n 2} & \dots & d_{n n} & P_{n} \\ A_{1} & A_{2} & \dots & A_{n} \end{matrix}

where:

$d_{i j} :$ number of trips from TAZ $i$ to TAZ $j$
$P_{i} :$ tot number of trips generated by TAZ $i$
- It's the sum of the colums
$A_{i} :$ tot number of trips attracted by TAZ $j$
- It's the sum of the rows
$n :$ tot number of TAZs

I - Trip generation

In trip distribution, we model the total trip Production (P) and Attraction (A) of each TAZ. These numbers are known as marginal totals.

This is done usually through linear regression models. We will obtain:

$P_{i} = f (pop, land use, job places)$
$A_{j} = f (pop, land use, job places)$

After this step, we have models for real $P$ and $A$ and for predicted values, $\hat{P}$ and $\hat{A}$ . We need to fill the $i j$ entries of the matrix

II - Trip distribution

In this step we fill in every $i j$ entry of the OD matrix. We are also able, in this process, to predict the demands for future years, once a model has been validated in the present.

III - Mode choice

In this step we model how many trips from $i$ to $j$ are made made using mode $k$ . We get from a unique matrix a set of k matrixes for each and every mode.

IV - Route choice

This is the assignment step where we start from a network and matrixes and we assign each trip to a specific route, combining road paths to Public Transportation.

3 - Forecasting

The stage 3 includes the forecasting in the future of demand, according to new land use and/or changes in the Transport System

4 - Evaluation

The stage 4 includes the evaluation of every scenario and alternatives

Activity-based modeling

This is an alternative approach from the #Classic 4 stage framework, where the base unit of analysis is shifted from the trip and the person becomes the center of the modeling. In this approach we basically consider the whole day of a person and all the activity they do

The basic approach still remains valid. We still use OD matrices and the zoning system (TAZ).