The shaft eliminates all the traffic jams. If you look at the pdf for the proposed L13 ramp you can imagine getting ore out and equiptment back in. Once you mine to a certain depth with the ramps you can the determine the best location for a shaft and dig upwards. HM had mentioned earlier that it is easier to dig up. Although the initial cost is higher, the saving make up for it in the end. We have so many deposits near surface we probably won't need another shaft for many years, however I am sure it is in the future with some of the richest deposits down deep.