Jean-Paul Rodrigue (2013), New York:
Routledge, 416 pages.
Methods in Transport Geography
Author: Dr. Jean-Paul Rodrigue
1. Transportation and Methodologies
Transportation is not a science, but a field of inquiry and
application. 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 with the use of inferential statistics, abstract models
and new theories. Although this perspective provided much needed rigor,
it also favored a disconnection between empirical and theoretical approaches.
Like in economics, the quantitative revolution led to a mechanistic
perspective where concordance to reality became somewhat secondary;
realities were made to fit into models. 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.
These constraints can be capacity, cost, time, environmental impacts,
but more often in combination.
It is consequently possible to identify relevant strategies and policies
and provide some scenarios about their possible consequences.
Like in geography, spatial and temporal process cannot be
considered separately. A basic taxonomy can divide them into transport-related methods
and multidisciplinary methods.
2. Transport-Related Methods
A first group of methods concern those directly related to the study
of transportation since most draw their origins from transport planning.
The methods mainly used in transport geography include:
- Whether they are qualitative or quantitative.
- Whether they deal with infrastructures (e.g. terminals) or flows.
- Whether they provide 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.
In addition, there are various methods of general use in transportation
studies to are readily applicable in transport geography:
- Network analysis (also referred to as graph theory),
which is used to study transport network forms and structures,
particularly how they change in time. For example, one could use network analysis to study
the evolution of the hub-and-spoke configuration of airline services.
- 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.
3. Multidisciplinary Methods
Include the whole range of methods that were not specifically developed
for transportation studies, but are readily applicable to its analysis.
They are labeled as multidisciplinary since they can be applied to a
wide range of issues irrespective of the discipline. First, there are methods that are central to geography,
but are not restricted to the study of transportation systems:
- First, a diverse set of techniques is used in the urban transportation modeling exercise, the purpose of which
is to understand and predict urban spatial patterns.
- Second, traffic surveys that are used to gather empirical
information about movements such as their routing and frequency.
Second, there are various methods that are used in many different
applications, including transportation analysis. They underline that
transportation analysts are not restricted to those methods that have
been developed with transportation in mind, but to whatever is relevant
to a specific problem. In fact, many methods that were initially developed
for other problems have widespread use in transportation studies:
- Cartography is the most obvious example of a geographic
technique. Indeed, various types of maps are used in the analysis
of transport systems, including land use maps, depictions of transport
infrastructure, isoline maps of transportation costs, or schematics
of transportation activity patterns.
- 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 development and application of methods to transport
studies in general and transport geography in particular has
been increasingly complex, particularly as improvements in
information technologies made available more powerful analytical
tools. For instance, a commercial geographic information system
package has analytical and modeling capabilities well beyond of
what is undertaken by most researchers, analysts or policy
makers. Future developments are therefore more likely to focus
on empirical data analysis using known methods but with more
extensive datasets. This will lead to more detailed and
consequential analysis of real world transport phenomena and
help better connect theoretical knowledge and real world
- Some methods are used to collect primary data
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, such as inferential statistics like the t-test,
analysis of variance, regression and chi-square.
- Increasingly, transportation studies are concerned with impacts
and public policy issues. They rely more on qualitative information
such as policy statements, rules and regulations. Various types
of impacts are considered, including economic (e.g. community development),
social (e.g. access to 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.