1. Introduction
Transportation is not a science, but a field of inquiry and application.
As such, it tends to rely on a set of specific methodologies since transportation is a
performance driven activity and this performance can be measured. Transportation
planning and analysis are interdisciplinary by nature, involving civil
engineers, economists, urban planners and geographers (see
concept 1). Each has developed methodologies dealing with their respective
array of problems. Two common traits of transportation studies, regardless of
disciplinary affiliation, are a heavy reliance on empirical data and
the
intensive use of data analytic techniques, ranging from simple descriptive
measures to more complex modeling structures.
In some respects, transport geography stands out from many other fields of
human geography by the nature and function of its quantitative analysis. In
fact, transport geography was one of the main forces in the quantitative
revolution that helped to redefine geography in the 1960s. Even if contemporary
transport geography has a more diversified approach, the quantitative dimension
still plays an important part in the discipline.
Thus, in addition to providing a conceptual background to the analysis of
movements of freight, people and information, transport geography is much an
applied science. The main goal of methods aims to improve the efficiency
of movements by identifying their spatial constraints. It is consequently
possible to identify relevant strategies and policies and provide some scenarios
about their possible consequences.
2. Overview
There are various ways of classifying the methods that are used by transport
geographers:
- Whether they are qualitative or quantitative.
- Whether they deal with infrastructures or flows.
- Whether it provides interpolation or extrapolation.
- Whether the technique provides description, explanation or optimization.
- According to the level of data aggregation, the nature of the assumptions
or the complexity of the calculations).
The following two-by-two classification scheme has been chosen.
| Methods |
Used Mainly in Transportation Studies |
General Use |
| Used Mainly in Geographic Studies |
- Network Analysis (Graph Theory)
- Land Use - Transportation Interactions
- Flow/Location Allocation Models
|
|
| General Use |
- The Four-Stage Urban Transportation Model
- Travel/traffic Surveys
|
- Questionnaires, Interviews
- Graphs and Charts
- Inferential Statistics
- Environmental Impact Assessment
- Risk Assessment
- Policy Analysis
|
The top left cell identifies methods that
are used mainly in transport geography. The best example of this is network
analysis (also referred to as graph theory), which is used to study
transport network form and structure, especially over time. For example, one
could use network analysis to study the evolution of the hub-and-spoke configuration
of airline service in North America.
- Transport geographers also play a key role in studying land use - transport
interactions. Numerical models have been developed, which, over time,
have become increasingly complex.
- Transport geographers are also interested in flow and location allocation
models that can be used to define such things as school district boundaries
or the location for a new retail outlet. These techniques are optimization
procedures rather than methods for describing or understanding current
transport systems.
The top right cell includes methods
that are central to the discipline of geography, but are not restricted to the
study of transportation systems.
- Map-making is the most obvious example of a geographic technique.
Indeed, various types of maps are included in this web site. These include
land use maps, depictions of transport infrastructure, isoline maps of transportation
costs, schematics of transportation activity patterns, and many more.
-
Geographic information systems (GIS), which are an outgrowth of digital
cartography, provide a set of tools for storing, retrieving, analyzing and
displaying spatial data from the real world. GIS technology has been applied
to some large-scale transportation planning and engineering applications.
More often, however, GIS are applied in a prescriptive way to small-scale
problems, for example to plot optimal routes for buses, delivery trucks, or
emergency vehicles.
- There are also various statistics that have been developed or modified
by geographers to describe urban-economic systems. Examples include the Gini
coefficient and indexes of concentration and specialization.
The bottom left cell includes various methods
that are in general use in transportation studies.
- First, a diverse set of techniques is used in the four-stage urban
transportation modeling exercise, the purpose of which is to understand
and predict spatial patterns of travel in urban areas.
- Second, traffic surveys that are used to gather empirical information
about movements.
The bottom right cell includes various
techniques that are used in many different applications, including transportation
analysis. Transportation analysts are not restricted to those techniques that
have been developed with transportation in mind. In fact, many methods that
were initially developed for other problems have widespread use in transportation
studies.
- Some methods are used to collect primary data, e.g. questionnaires
and interviews, while others are used to analyze data. Some of the analytic
techniques are straightforward to implement and interpret; graphs (e.g. scattergrams,
distance-decay curves) and tables (e.g. origin-destination matrices) are two
examples. Others are more complex, e.g., inferential statistics like the t-test,
analysis of variance, regression and chi-square.
- Increasingly, transportation studies are concerned with impacts and
public policy issues. Various types of impacts are considered, including
economic (e.g. community development), social (e.g. the equity of access to
essential services), environmental (e.g. air or water pollution) and health
(e.g. road accidents). The broad fields of environmental impact assessment
, risk assessment and policy analysis are relevant to these issues.
Copyright © 1998-2008, Dr. Jean-Paul Rodrigue, Dept. of Economics & Geography,
Hofstra University. For personal or classroom use ONLY. This material (including
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