Scheme Appraisal for Highway Projects 47the ‘do-nothing’ scenario does however ensure that, in addition to the various
‘live’ options being compared in relative terms, these are also seen to be eco-
nomically justified in absolute terms, in other words their benefits exceed their
costs.
The term ‘feasible’ refers to options that, on a preliminary evaluation, present
themselves as viable courses of action that can be brought to completion given
the constraints imposed on the decision-maker such as lack of time, informa-
tion and resources.
Finding sound feasible options is an important component of the decision
process. The quality of the final outcome can never exceed that allowed by the
best option examined. There are many procedures for both identifying and
defining project options. These include:
Drawing on the personal experience of the decision-maker himself as well
as other experts in the highway engineering field
Making comparisons between the current decision problem and ones
previously solved in a successful manner
Examining all relevant literature.
Some form of group brainstorming session can be quite effective in bringing
viable options to light. Brainstorming consists of two main phases. Within the
first, a group of people put forward, in a relaxed environment, as many ideas as
possible relevant to the problem being considered. The main rule for this phase
is that members of the group should avoid being critical of their own ideas or
those of others, no matter how far-fetched. This non-critical phase is very
difficult for engineers, given that they are trained to think analytically or in a
judgmental mode (Martin, 1993). Success in this phase requires the engineer’s
judgmental mode to be ‘shut down’. This phase, if properly done, will result in
the emergence of a large number of widely differing options.
The second phase requires the planning engineer to return to normal judg-
mental mode to select the best options from the total list, analysing each for
technological, environmental and economic practicality. This is, in effect, a
screening process which filters through the best options. One such method is to
compare each new option with an existing, ‘tried-and-tested’ option used in pre-
vious similar highway proposals by means of a T-chart (Riggs et al., 1997). The
chart contains a list of criteria which any acceptable option should satisfy. The
option under examination is judged on the basis of whether it performs better
or worse than the conventional option on each of the listed criteria. It is vital
that this process is undertaken by highway engineers with the appropriate level
of experience, professional training and local knowledge in order that a suffi-
ciently wide range of options arise for consideration.
An example of a T-chart is shown in Table 3.1.
In the example in Table 3.1, the proposed option would be rejected on the
basis that, while it had a lower construction cost, its maintenance costs and level
of environmental intrusion and geometric design, together with its low level of