CHAPTER 6
PROJECT INTERACTIONS, SIDE COSTS AND SIDE BENEFITS
In much of our discussion so far, we have assessed projects independently of
other projects that the firm already has or might have in the future. Disney, for instance,
was able to look at the theme park investment and analyze whether it was a good or bad
investment. In reality, projects at most firms have interdependencies with and
consequences for other projects. Disney may be able to increase both movie and
merchandise revenues because of the new theme park in Bangkok and may face higher
advertising expenditures because of its Asia expansion.
In this chapter, we examine a number of scenarios in which the consideration of
one project affects other projects. We start with the most extreme case, where investing in
one project leads to the rejection of one or more other projects; this is the case when
firms have to choose between mutually exclusive investments. We then consider a less
extreme scenario, where a firm with constraints on how much capital it can raise
considers a new project. Accepting this project reduces the capital available for other
projects that the firm considers later in the period and thus can affect their acceptance;
this is the case of capital rationing.
Projects can create costs for existing investments by using shared resources or
excess capacity, and we consider these side costs next. Projects sometimes generate
benefits for other projects, and we analyze how to bring these benefits into the analysis.
In the final part of the chapter, we introduce the notion that projects often have options
embedded in them, and that ignoring these options can result in poor project decisions.
Mutually Exclusive Projects
Projects are mutually exclusive when only one of the set of projects can be
accepted by a firm. Projects may be mutually exclusive for different reasons. They may
each provide a way of getting a needed service, but any one of them is sufficient for the
service. The owner of a commercial building may be choosing among a number of
different air-conditioning or heating systems for a building. Or, projects may provide
alternative approaches to the future of a firm; a firm that has to choose between a “high-