No abstract

In this research, an optimization framework is proposed to find the system-optimal solution for the emergency evacuation planning problem. The model simultaneously solves for the choice of destination (shelter), evacuation route, and departure time for all evacuees from given origins (endangered zones). Heuristic algorithms are proposed to find the system-optimal dynamic traffic assignment during an iterative procedure. A mesoscopic traffic simulator is embedded in the optimization modules to find travel time marginals and obtain required performance measures in every iteration. Implementing the proposed algorithm brings about dramatic improvements in network performance measures such as total travel time and network clearance time in a case study of Ocean City, Maryland.

Recently, capacity models have been developed for single- and double-lane roundabouts by using U.S. data from NCHRP Report 572. The model for double-lane capacity was provided primarily for critical lane (usually right-lane) capacity as a function of total circulating volume. None of the existing international capacity models separate circulating volumes by lane. This study proposes planning capacity models for two-lane and three-lane roundabouts by separate entry-lane and separate circulatory-lane traffic volumes. VISSIM microsimulation software was used first to compare with the new NCHRP models as well as with Australian (SIDRA) and German (Tanner-Wu) models. Given that predictions from VISSIM for overall capacity of one- and two-lane roundabouts are consistent with U.S. data from NCHRP Report 572, new planning capacity models were developed by using VISSIM for the left lane and right lane of double-lane roundabouts that are functions of separate circulatory-lane traffic volume. For three-lane roundabouts, planning capacity models were developed by separate entry lane (left, middle, and right lane) as functions of inner, middle, and outer circulatory-lane volumes. All variable coefficients are statistically significant, and model fits are strong.

The FAA's Air Traffic Organization (ATO) Office of Performance Analysis is responsible for developing indicators and providing analysis on the operational efficiency of the NAS and to ensure its databases provide the necessary information for linking performance to root causes. The focus of this paper is the primary indicator of capacity within a sector, the Monitor Alert Parameter (MAP), an indicator designed to alert personnel when traffic levels in a given sector may be at a level that will affect the efficiency of the system. Over the past decade, however, it has come under some criticism for being too simplistic in its calculation with the obvious implication that some MAP values do not represent the real trigger point at which the balance between sector capacity and traffic volume require a closer look. A search for studies on this subject yields sparse results with cursory connections. This paper will review and analyze the current FAA policy for MAP and discuss the challenges and potential shortfalls of the current implementation of baseline MAP values. Further, it will discuss the challenges associated with measuring the effectiveness of this tool. Finally, this paper draws conclusions and makes recommendations focused on enabling a more comprehensive analysis of sector capacity limitations on the efficiency of the NAS.