Jean-Paul Rodrigue (2017), New York:
Routledge, 440 pages.
The Route Selection Process
Author: Dr. Jean-Paul Rodrigue
Human beings are natural effort minimizers, notably
when it involves moving around. When given the opportunity, they will
always try to choose the shortest path to go from one place to
another. This behavior can easily be observed from pedestrians. When
possible, a pedestrian will
walk over a lawn,
zigzag by cars in a parking lot, or cross a street sideways between
intersections if the route selected enables to reach faster a destination.
Transportation, as an economic activity, replicates this process
of minimization, notably by trying to minimize the friction of distance
between locations. Shorter times and lower costs are looked upon by
individuals as well as by multinational corporations. For an individual,
it is often only a matter of convenience, but for a corporation it is
of strategic importance as a direct monetary cost is involved. Under
such circumstances, it is not surprising that numerous methods have
been developed to deal with the often complex issue of route selection.
One such classic application is the
"traveling salesperson" problem,
where the shortest route has to be selected from a set of numerous combinations
of possible paths.
Route selection has two major dimensions:
2. Evaluating the Route Selection Process
The choice of linking a location to another, and more importantly,
the path selected is part of a route selection process which
respects a set of constraints. Although route selection varies by mode,
the underlying principles remain similar; in its most simple form, a
route selection process (R) tries to respect these general constraints:
Route selection thus tries to find or use a path minimizing costs
and maximizing efficiency. There are obviously two major dimensions
in this function:
Involves activities related to the setting of transport networks
such as road and rail construction. Among the basic considerations
are factors such as distance and topography.
Concerns the management of flows in a network. This is the most
common route selection activity since it considers routes as
fixed entities and therefore seek an optimal path considering
Route selection is consequently a
the cost of a transport service and its efficiency. Sometimes, there
are no compromises as the most direct route is the most efficient one.
At other times, a compromise is very difficult to establish as cost
and efficiency are inversely proportional.
- Cost minimization. A good route selection should minimize
the overall costs of the transport system. This implies construction
as well as operating costs. The most direct route is not
necessarily the least expensive, notably if rugged terrain is concerned,
but most of the time a direct route gets selected. It also implies
that route selection must be the least damageable to the environment,
if environmental consequences are considered.
- Efficiency maximization. A route must support economic
activities by providing a level of accessibility, thus fulfilling
the needs of regional development. Even if a route is longer and
thus more expensive to build and operate, it might provide better
services for an area. Its efficiency is thus increased at the expense
of higher costs. In numerous instances, roads were constructed more
for political reasons then for meeting economic considerations.