Many installations involve splitting the fibers in a backbone cable into one or more other cables or dropping a small fiber count cable from a large backbone cable. Backbone cables of 144-288 fibers are common and larger ones are becoming more common too. Drop cables are often only 2-12 fibers, meaning most fibers are continuing straight through the drop point. Midspan access involves opening the cable by removing the jacket and strength members, opening the buffer tube and splicing only the fibers being dropped at that point. The untouched buffer tubes from the opened cable are carefully rolled up and stored in the same splice closure as the fibers that will be separated and spliced to a drop cable.
This FOA Lecture will explain what midspan access is and how it is done.