Vague and Unsourced  This statement near the end is vague and unsourced Three carriages including the bar carriage in the centre is the minimum possible configuration because of the way the sets are articulated   Does this mean three carriages exclusive of the power cars or can the power cars be the other two carriages  Why are three carriages including the bar carriage needed The way the sets are articulated makes no sense  Given these problems the statement should be sourced and clarifiedor else deleted probably the better option