This has been tried many times before, to date all have failed, why will ATS and ULTra succeed?
Perhaps earlier attempts were before their time. In the 1970s a model was established which nearly all PRT systems have adopted since then. ATS started with a clean sheet and have a new approach to PRT which has a wide number of improvements over the older ideas. ATS has also taken advantage of the considerable recent advancements in technology and computing.