The above discussion compares line or corridor capacity and may therefore not be relevant for a networked PRT system, where several parallel lines (or parallel components of a grid) carry traffic. In addition, Muller estimated that while PRT may need more than one guideway to match the capacity of a conventional system, the capital cost of the multiple guideways may still be less than that of the single guideway conventional system. Thus comparisons of line capacity should also consider the cost per line.