Scheduling Lane Conversions for Bus Use on City-Wide Scales and in Time-Varying Traffic
- Author(s): Saade, Nathalie
- Advisor(s): Cassidy, Michael
- Gu, Weihua
- et al.
The dissertation explores what can occur when select street lanes throughout a city are periodically reserved for buses. Simulations of an idealized city were performed to that end. The city’s time-varying travel demand was studied parametrically. In all cases, queues formed throughout the city during a rush, and dissipated during the off-peak period that followed. Bus lanes were activated all at once across the city, and were eventually deactivated in like fashion. Activation and deactivation schedules varied parametrically as well. Schedules that balanced the trip-time savings to bus riders against the added delays to car travelers were thus identified.
Findings reveal why activating conversions near the start of a rush can degrade travel, both by car and by bus. Balance was struck by instead activating lane conversions much closer to the subsidence of rush demand. Most of the time savings to bus riders accrued after the conversions had been left in place for only 30 mins. Leaving them for longer durations often brought modest additional savings to bus travelers. Yet, the added delays to cars often grew large.
These findings held even when buses garnered high ridership shares, whether or not those higher shares were induced over time. Activating conversions early in a rush was found to make sense only if commuters shifted from cars to buses in high numbers. Findings also unveiled how to fine-tune activation and deactivation schedules to suit a city’s congestion level. Guidelines are offered for scheduling conversions in real settings. Discussion on how these schedules might be adapted to daily variations in city-wide traffic states is offered as well.