Chapter 3
Scheme Appraisal for Highway Projects
3.1 Introduction,
Once a transportation plan has been finalised and the demand along each of its
highway links has been established, a process must be put in place that helps
identify the best solution for each individual proposal within the highway
network. Each project must therefore be subject to an appraisal.
The aim of the highway appraisal process is therefore to determine the eco-
nomic, societal and environmental feasibility of the project or group of projects
under examination. The process enables highway planners to decide whether a
project is desirable in absolute terms and also provides a means of choosing
between different competing project options, all of which have the ability to meet
the stated goals and objectives of the project sponsors.
The ‘reasoned choice’ model of individual or group decisions provides a
decision-making framework within which scheme appraisal can take place,
providing a technical foundation for non-recurring decisions such as the assess-
ment of a highway construction/improvement proposal (Zey, 1992). It comprises
the following steps:(1) Problem recognition. The decision-maker determines that a problem exists
and that a decision must be reflected on.
(2) Goal identification. The decision-maker details the desired result or out-
come of the process.
(3) Identification of alternative highway schemes. Different potential solutions
are assembled prior to their evaluation.
(4) Information search.The decision-maker seeks to identify characteristics
associated with the alternative solutions.
(5) Assessment of information on alternative highway schemes. The information
necessary for making a decision regarding the preferred option is gathered
together and considered.
(6) Selection of preferred highway scheme.A preferred option is selected by the
decision-maker for implementation in the future.
(7) Evaluation. The decision is assessed a period of time after its implementa-
tion in order to evaluate it on the basis of its achieved results.