Rail line length in a crosstown corridor with many-to-many demand

An analytical model that determines the optimal location and length of rail line along a crosstown transportation corridor with the objective of minimizing the total transportation cost is presented. A general, many-to-many passenger demand pattern is considered. The objective function, which includes the rail and bus riding costs, rail and bus operating costs, rail fleet costs and rail line costs, is minimized by using the classical optimization method with the aid of a computer program developed for the model. The model is applied to the Northwest-South transportation corridor in Calgary, Alberta, and the sensitivity of the optimal rail line location and length to the unit cost and demand parameters at their reasonable ranges is tested. It is found that although the total passenger demand, unit rail line cost, and unit bus operating cost have greater influence than the unit bus and rail riding costs, and unit rail fleet and operating costs, the optimal line length is generally insensitive to all these parameters. It is also found that the length of the existing LRT line in the corridor is comparable to the optimal line length obtained from the model, but the existing line should be extended further south in order to meet the heavier demand in that direction optimally.     

TOD真的需要公共交通吗?——轨道交通可达性以外的重要因素探讨

以公共交通为导向的发展模式(TOD)通常包括在轨道交通车站周边新建住房。引导城市按照这样的模式发展,其目的部分在于减少气候变化、污染以及机动车导致的拥堵。但是,新建住房可能会更容易吸引那些开车较多的富裕家庭,相比房屋所有权和大小、停车供给、街区和分区建筑环境,轨道交通可达性对汽车拥有和使用的影响可能也较弱。通过调查居住在新泽西州北部10个轨道交通车站2英里半径范围内的家庭,收集有关房龄和类型、路外停车位可达性、工作和非工作的出行方式、人口特征以及选择所住街区原因的数据。对调查数据进行地理编码,并与实地调查的路内停车数据、街区和分区建筑环境指标等数据相融合。分析这些因素如何与调查中所记录的汽车拥有和使用情况相关联。住在轨道交通车站附近新房子内的家庭,在汽车拥有、利用汽车通勤以及购物出行频率上明显低于那些住在远离轨道交通的新房子内的家庭。但是,轨道交通可达性在这一差别中起到的作用很小。房屋类型和所有权、局部和分区密度、公共汽车服务、特别是路外及路内停车供给对差异的产生发挥了更重要的作用。     

Multisite,Interdisciplinary Applications of Science to Marine Policy: The Conservation International Marine Management Area Science Program

This special issue provides insight into global conservation science by analyzing a 5-year, $12.5 million global marine conservation science and policy program that included over 50 studies in four priority regions involving over 100 scientists and numerous partners. In doing so, it provides reflections on critical challenges for any conservation science program that is intended to inform policymaking, including how to (1) ensure that science process and products influence conservation actions, (2) build global learning from a network of site-based projects, (3) strengthen in-region capacity, and (4) manage relationships across scales among scientists, conservationists, headquarters, and field-based staff. Information is presented on the development and progress of the program as a whole in addition to specific articles covering each of four focal geographic areas: Belize, Brazil, the Eastern Tropical Pacific Seascape, and Fiji.     

Airport taxi planning: Lagrangian decomposition

The airport taxi planning (TP) module is a decision tool intended to guide airport surface management operations. TP is defined by a flow network optimization model that represents flight ground movements and improves aircraft taxiing routes and schedules during periods of aircraft congestion. TP is not intended to operate as a stand‐alone tool for airport operations management: on the contrary, it must be used in conjunction with existing departing and arriving traffic tools and overseen by the taxi planner of the airport, also known as the aircraft ground controller. TP must be flexible in order to accommodate changing inputs while maintaining consistent routes and schedules already delivered from past executions. Within this dynamic environment, the execution time of TP may not exceed a few minutes. Classic methods for solving binary multi‐commodity flow networks with side constraints are not efficient enough; therefore, a Lagrangian decomposition methodology has been adapted to solve it. We demonstrate TP Lagrangian decomposition using actual data from the Madrid‐Barajas Airport. Copyright © 2011 John Wiley & Sons, Ltd.     

Using risk analysis to determine the potential range of lifecycle costs for urban transit systems

Intense competition for limited public funding for urban transport projects can often result in proponents of individual schemes presenting minimized costs and maximized benefits to funding bodies to try to ensure that their scheme is chosen above others for funding. This presents public bodies with a problem, especially in an era when they are keen to attract private contributions for transit schemes. Risk modelling techniques can be of great assistance in ascertaining ranges of costs and benefits for individual submissions and deciding upon which projects should receive priority-not only those with greatest cost-benefit indices, but also those whose indices have low levels of associated risk to allay the fears of the traditionally risk averse private sector.     

Evaluating the impact of legislation prohibiting hand-held cell phone use while driving

As of November 2008, the number of cell phone subscribers in the US exceeded 267 million, nearly three times more than the 97 million subscribers in June 2000. This rapid growth in cell phone use has led to concerns regarding their impact on driver performance and road safety. Numerous legislative efforts are under way to restrict hand-held cell phone use while driving. Since 1999, every state has considered such legislation, but few have passed primary enforcement laws. As of 2008, six states, the District of Columbia (DC), and the Virgin Islands have laws banning the use of hand-held cell phones while driving. A review of the literature suggests that in laboratory settings, hand-held cell phone use impairs driver performance by increasing tension, delaying reaction time, and decreasing awareness. However, there exists insufficient evidence to prove that hand-held cell phone use increases automobile-accident-risk. In contrast to other research in this area that uses questionnaires, tests, and simulators, this study analyzes the impact of hand-held cell phone use on driving safety based on historical automobile-accident-risk-related data and statistics, which would be of interest to transportation policy-makers. To this end, a pre-law and post-law comparison of automobile accident rate measures provides one way to assess the effect of hand-held cell phone bans on driving safety; this paper provides such an analysis using public domain data sources. A discussion of what additional data are required to build convincing arguments in support of or against legislation is also provided.     

An application of shock wave theory to traffic signal control

A real time control policy minimizing total intersection delays subject to queue length constraints at an isolated signalized intersection is developed in this paper. The policy is derived from a new traffic model which describes the simultaneous evolution of queue lengths of two conflicting traffic streams, controlled by a traffic light, in both time and space. The model is based on the examination of shock waves generated upstream of the stop lines by the intermittent service of traffic at the signal. The proposed policy was tested against the existing pre-timed control policy at a high volume intersection and it was found superior, especially when demands increase well above the saturation level.     

ITS applications for work zones

The use of Intelligent Transportation Systems (ITS) in construction work zones to disseminate traffic information has increased significantly in recent years, mainly with the use of Variable Message Signs (VMS). VMS are used based on the assumption that informed drivers will make better travel decisions, thereby reducing congestion. However, the extent of change in driver behavior is difficult to predict prior to ITS deployment. This difficulty leads to the larger problem of justifying investment in ITS. This article proposes an ITS deployment decision support tool using micro‐simulation. The approach determines the required diversion effectiveness of a work zone ITS deployment using VMS. The methodology was tested using the Glenmore Trail/Elbow Drive/5^th Street interchange project (GE5) in Calgary, Canada. The results indicate that the proposed approach will assist agencies in justifying ITS investment by exhibiting the potential resultant societal benefits.