original_query: What were the arguments in favor of constructing a completely new set of guideways?
query: What were the arguments in favor of constructing a completely new set of guideways for the Tracked Hovercraft?
answer: The main argument was that placing the competing Advanced Passenger Train (APT) on existing lines would increase congestion.  Additionally, the APT's speed was too low to compete with jet aircraft, unlike the Tracked Hovercraft's significantly higher speed.  If new lines were to be built anyway, the Tracked Hovercraft's construction cost was considerably less per mile than upgrading existing lines to comparable speeds.