Access is a binary measure of accessibility where an activity is either reached across a network or not. The first instance of an activity reached when searching outwards from a point provides access. Being able to reach subsequent instances of the same activity, does not improve this binary measure. However, reaching subsequent instances of the same activity does improve the opportunity for the consumer to realise the activity. The first instance of an activity provides access, subsequent instances provide choice (of services, cost etc), improving the opportunities available to the consumer of the services.
Accessibility to a choice of destinations is of value, but the extra marginal value provided by successive opportunities decreases. This is because each new choice increases the total pool of activity providers, and therefore comprises a smaller fraction of the increasing pool of choices. At some point this diminishing rate of return means the benefit gained by reaching an additional opportunity is no longer significant, effectively reaching a state of ‘saturation of opportunities’.