So long as the passenger has in mind a destination and that destination is on or near the rail line, this is a good system. However, rapid and easy movement along established lines and to established points may not necessarily be efficient. The passenger whose destination is not on the line may travel the rails as a part of the journey, yet take a bus or car some considerable distance as another part. The geologist or archaeologist may have to leave all roads entirely. The salesperson or politician may have to stop in places and at times that cannot be accommodated by rail lines and so takes a bus or an airplane.
Efficiency is a measure of the degree to which certain goals or criteria are met.
The speed of operation of a system, its fuel economy, its percentage of downtime, and its load capacity may be efficiency measures for some people, but not for others. The rail lines are highly efficient for some purposes, moderately so for some, and not at all for others. Indexing and abstracting are similar to train systems. In most instances, the steering has been accomplished beforehand. Indexing terms have been constructed or extracted, classification categories established, and abstracts written before a system user engages the system.