A parametric analysis of a PRT system for southwest Houston
Smith, Rodney L.
Krahl, Nat W.
Master of Science
This thesis presents an analysis of several aspects of an emerging form of urban transportation - Personal Rapid Transit (PRT). The potential of PRT for some portion of the urban transportation demand is first discussed to determine if there is the need for the development and implementation of PRT. The advanced technology required for a city-wide PRT system is discussed in an effort to assess the availability of the required technology within a realistic time period. The urban design implications and the phasing of an extensive PRT system are discussed in order to determine the desirability of such a system. Indications are that there is a need for PRT in a comprehensive urban transportation network, that the necessary technology can be made available in a realistic time frame, and that PRT would probably have desirable effects on the development of an urban area. The rest of the thesis investigated the patronage estimates for several PRT system characteristics. Many proponents of PRT claim that a PRT system could effectively compete with the auto for trips made within a low density urban area. To test this, trips internal to the southwest quadrant of Houston were analyzed using computer simulations for test PRT and road systems. A parametric analysis was performed to determine the sensitivity of PRT patronage to several of the transportation system characteristics operating velocities, out-of-pocket costs, system configurations, etc. in an effort to determine PRT design characteristics and resulting patronage levels. Analysis of the test PRT systems indicated that PRT patronage was most sensitive to the connection speed to transit (a 1 mph bus-type connection appears to be a necessity), transit wait time (a total wait time for transit of five minutes effectively eliminates PRT as a viable alternative to the auto), and a perceived "hassle factor" associated with utilizing transit. Average auto velocity and perceived auto operating cost also had significant effects for specific ranges of these two variables. Variations in total trip length, PRT fare, and PRT vehicle velocity were found to have only slight effects on PRT ridership. The configuration of the PRT system appears to significantly affect PRT ridership levels. Station placement was identified as a critical factor: a total walk distance of over 1, feet for a trip utilizing PRT effectively reduces PRT patronage levels to zero. The circuitousness of several PRT paths, when competing with the more direct paths of the auto network, is partially responsible for reduced PRT patronage levels. PRT paths closely paralleling freeways were projected to carry reduced loads due to the higher velocities and lower costs associated with auto trips by freeways. Simulations indicate that PRT would not carry a significant portion of the total trips internal to southwest Houston. Longer trips, however, destined for activity centers appreciably beyond the study limits assessed with high auto parking charges were found to generally be more accessible to southwest Houston by PRT than by auto. PRT, therefore, would seem to function much more effectively as a feeder system to major activity centers than as a local transportation system for a low density urban area.