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The paper 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 roughly 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 nearer the end of the rush, when vehicle accumulation in the city was at or near its maximum. Most of the time savings to bus riders accrued after the conversions had been left in place for only 30 min. Leaving them for longer durations often brought modest additional savings to bus travelers. Yet, the added delays to cars often grew large as a result. These findings held even when buses garnered high ridership shares. This was the case when lane conversions gradually induced new bus trips among residents who formerly did not travel. It was also true when high ridership was a pre-existing feature of the city. Activating conversions a bit earlier in a rush was found to make sense only if commuters shifted from cars to buses in very large numbers. Findings also unveiled how to fine-tune activation and deactivation schedules to suit a city’s congestion level. Guidelines for scheduling conversions in real settings are furnished. So is discussion on how these schedules might be adapted to daily variations in city-wide traffic states. Roles for technology are discussed as well.

In this paper, we estimate the impacts of post-departure flight rerouting on times of arrival at destination airports. There are mainly two types of post-departure reroutes – opportunistic reroutes (distance-saving reroutes) and reactive reroutes (distance-increasing reroutes). To the best of our knowledge, the downstream impact of rerouting has received little attention in the existing literature; however, the benefit/harm of both kinds of reroutes might be exaggerated if their system impact is not taken into account. Thus, we developed a framework for evaluating the net effect of applying a reroute at the system level by analyzing its impact on arrival times at the destination of the rerouted flight. We focus on reroutes that affect en route flight time by 5 min or more. Adopting a “multiplier” concept that was proposed in previous research and making use of two-year (2013–2014) flight level data at the 34 main airports in the US, we analyze how the en route time change affects cumulative arrival throughput at the destination airport, and the associated time savings or time costs. We find that these impacts of reroutes differ remarkably at different airports, and identify airports where the arrival time impact is highly correlated with the en route time change as well as those for which this correlation is weak. In addition, we compare downstream impacts among different types of reroutes. Finally, we study cases with very high multipliers in detail in order to identify these circumstances under which they occur.

In an effort to relieve peak hour congestion on freeways, various ramp metering algorithms have been employed to regulate the inputs to freeways from entry ramps. In this paper, we consider a freeway system comprised of a freeway section and its entry/exit ramps, and formulate the ramp control problem as a dynamic optimal process to minimize the total time spent in this system. Within this framework, we are able to show when ramp metering is beneficial to the system in terms of total time savings, and when it is not, under the restriction that the controlled freeway has to serve all of its ramp demand, and the traffic flow process follows the rules prescribed by the LWR theory with a triangular flow-density relationship. We also provide solution techniques to the problem and present some preliminary numerical results and empirical validation.