48 Highway Engineering
time savings for motorists, would eliminate it from further consideration. The
example illustrates a very preliminary screening process. A more detailed, finer
process would involve the use of percentages rather than checkmarks. The level
of filtering required will depend on the final number of project options you wish
to be brought forward to the full evaluation stage.3.3.3 Identifying all relevant costs and benefits
The application of cost-benefit for project assessment in the highway area is
made more complicated by the wide array of benefits associated with a given
road initiative, some easier to translate into monetary values than others. Many
of the benefits of improvements to transport projects equate to decreases in cost.
The primary grouping that contains this type of economic gain is termed user
benefits. Benefits of this type accrue to those who will actively use the proposed
installation. This grouping includes:
Reductions in vehicle operating costs
Savings in time
Reduction in the frequency of accidents.This is the main group of impacts considered within a standard highway CBA.
Other studies might address in some way a secondary grouping of benefits –
those accruing to ‘non-users’ of the proposed facility. These include:
Positive or negative changes in the environment felt by those people situated
either near the new route or the existing route from which the new one will
divert traffic. These can be measured in terms of the changes in impacts such
as air pollution, noise or visual intrusion/obstruction.
The loss or improvement of recreational facilities used by local inhabitants,
or the improvement or deterioration in access to these facilities.The costs associated with a proposed highway installation can fall into similar
categories. However, in most evaluations, construction costs incurred during the
initial building phase, followed by maintenance costs incurred on an ongoing
basis throughout the life of the project, are sufficient to consider.Proposed highway option vs. an Better Worse
accepted ‘tried and tested’ design
solution
Construction cost ✓
Maintenance cost ✓
Environmental impact ✓
Geometric design ✓
Time savings ✓Table 3.1Example of
T-chart for a highway
project