Curbside Service Subways

Currently proposed on-call (or demand actuated, or Personal Rapid Transit) systems cannot safely provide the desired line capacities. Scheduled trains lack the desired privacy, direct routing, and short trip time, while subways are penalized by the high cost and social undesirability of underground stations. The concept of curbside service subways reconciles these conflicting considerations to make on-call subway systems competitive in cost and performance for all classes or urban transportation. Characterizing features are: (1) small cable-driven vehicles circulating in a network of underground guideways; (2) headway maintenance by regularly spaced cable lugs; (3) vertical switching to and from offline stations at street level; (4) gravity braking and acceleration; and (5) level descent from stations. Safe headways of 0.5 sec at 30 mph appear possible with line capacities approaching 30,000 passengers per hr for four passenger vehicles. The inexpensive curbside stations can be spaced less than a block apart.