A GIS-based planning approach to locating urban rail terminals

This paper develops a flexible GIS-based methodology for evaluating the potential locations of terminal park-and-ride facilities along urban rail lines. The methodology differs from political-based approaches and traditional travel demand modeling in its use of an objective measure of accessibility to gage the suitability of a site. The methodology begins by constructing an index of derived demand for rail usage based on the local demographics. Principal component analysis (PCA) is used as a means of constructing an index of derived demand consistent with other passenger surveys. Next, trade areas or commutersheds are calculated for each candidate park-and-ride location based on realistic measures of accessibility and network based drive times, taking into account competition among candidates for riders. Following the analysis, the candidate locations and their commutersheds are delineated and visualized in the GIS environment. In summary, application of this method produces a site-specific suitability index that may be used to rank and compare potential park-and-ride locations. We illustrate how our approach fits within the context of the larger-scale corridor study as a complimentary means of refining the location of urban rail stations. The analysis uses the proposed rail system for Columbus Ohio as a case study. This revised version was published online in June 2006 with corrections to the Cover Date.     

A systems approach to area traffic control

Since the first pilot scheme for area‐traffic control was introduced in the city of Montreal (1959–60), computer control of traffic in urban areas through the adaptation of existing traffic‐signal systems has been provided to an increasing extent. This area of work may pose problems for the professional traffic engineer whose background in computer technology and general digital electronics may be limited.

In considering the engineering implications of such schemes a systems approach is important and is adopted here. Three existing and representative schemes are briefly mentioned in order to outline basic features. A more detailed examination of the various system elements follows with mention of data collection and transmission, and the role of the control computer.

The paper continues with a reconsideration of the three representative schemes in the light of the detailed treatment of system components. It concludes with a tentative assessment of the present position of area traffic control schemes and some suggestions as to the future development.     

A fuzzy measure based solution approach to a multimodal analysis problem

This paper discusses the factors that determine the utility of a mode and attempts to suggest and investigate a novel fuzzy measure based solution approach to the problem of multimodal analysis in a multicriteria context. The paper expands on the notions of fuzzy logic and in particular, fuzzy measures. The approach attempts to estimate the probabilities of the “overall system” from a group of eight experts who are experienced in transport planning. The data is used to ascertain the relative utility of various modes in a competitive environment. It explains the application of fuzzy measures to provide guidance information for a transport planning agency.     

城市地下铁道连拱隧道群施工技术研究

利用广州地铁三号线某一工程实例,对连拱隧道群施工工法进行探讨。在广州地铁施工中首次提出了将连拱隧道改为单洞隧道施工技术,并对单一式中墙和分离式中墙结构的技术方案进行了比选,得出了满足结构安全、施工安全和经济效益较好的技术方案,可为今后类似工程的设计和施工提供借鉴和参考。     

A planning methodology for intelligent urban transportation systems

Recent developments in intelligent transportation systems pose new challenges and opportunities for urban transportation planning. To meet these challenges and to exploit these opportunities, a framework for a new transportation planning methodology has been developed. The methodology operates in a computer environment, called PLANiTS (Planning and Analysis Integration for Intelligent Transportation Systems), designed to facilitate the entire planning process form problem identification, through idea generation and analysis, on to prioritization and programming. To assist in problem identification, PLANiTS provides graphic representation of current conditions, including traffic, air pollution, accidents, and projections of future conditions. A computerized knowledge base, containing information about possible strategies and their effects, and a model base, containing transportation and other analysis models, are used to guide the user in identifying potentially effective strategies and performing the appropriate analysis. To facilitate the use of these tools, PLANiTS provides computer support of group processes such as brainstorming, deliberation, and consensus seeking. PLANiTS is designed for use in urban transportation planning at the local, regional, and state levels; it is intended to support a variety of participants in the planning process including transportation professionals, decision makers in transportation agencies (often local elected officials), citizens, and interest groups. Recognizing that transportation planning is essentially a deliberative, political process, PLANiTS is designed to inform and facilitate, but not replace, the political decision-making process.     

A porous flow approach to modeling heterogeneous traffic in disordered systems

A continuum model that describes a disordered, heterogeneous traffic stream is presented. Such systems are widely prevalent in developing countries where classical traffic models cannot be readily applied. The characteristics of such systems are unique since drivers of smaller vehicles exploit their maneuverability to move ahead through lateral gaps at lower speeds. At higher speeds, larger vehicles press their advantage of greater motive power. The traffic stream at the microscopic level is disordered and defines a porous medium. Each vehicle is considered to move through a series of pores defined by other vehicles. A speed-density relationship that explicitly considers the pore space distribution is presented. This captures the considerable dynamics between vehicle classes that are overlooked when all classes are converted to a reference class (usually Passenger Car Equivalents) as is traditionally done. Using a finite difference approximation scheme, traffic evolution for a two-class traffic stream is shown.     

Selection of urban transportation systems

An information system is presented which identifies the transportation technologies suited to any one transportation need situation lying in a broad range of such situations. The system is concerned with people movement rather than goods movement. The user of the system specifies the nature and extent of demand, as well as certain service requirements. A transportation technology is identified as suited to a particular need situation when the technology meets the demand and the service requirements, and does so at reasonable cost. The technologies identified by the system as suited to a need situation must be examined to select the one best alternative. This final selection process is not part of the system. This system consists of two tables. Their use is described and examples are given. The procedure used to develop the tables is discussed. The system identifies new transportation technologies (PRT, AGT, etc.) as well as old.     

Road network vulnerability analysis of area-covering disruptions: A grid-based approach with case study

We present an approach to systematically analysing the vulnerability of road networks under disruptions covering extended areas. Since various kinds of events including floods, heavy snowfall, storms and wildfires can cause such spatially spread degradations, the analysis method is an important complement to the existing studies of single link failures. The methodology involves covering the study area with grids of uniformly shaped and sized cells, where each cell represents the extent of an event disrupting any intersecting links. We apply the approach to the Swedish road network using travel demand and network data from the Swedish national transport modelling system Sampers. The study shows that the impacts of area-covering disruptions are largely determined by the level of internal, outbound and inbound travel demand of the affected area itself. This is unlike single link failures, where the link flow and the redundancy in the surrounding network determine the impacts. As a result, the vulnerability to spatially spread events shows a markedly different geographical distribution. These findings, which should be universal for most road networks of similar scale, are important in the planning process of resource allocation for mitigation and recovery.     

Understanding urban mobility patterns from a spatiotemporal perspective: daily ridership profiles of metro stations

Transportation - Smart card data derived from automatic fare collection (AFC) systems of public transit enable us to study resident movement from a macro perspective. The rhythms of traffic...     

A GIS-Based approach for estimating truck flow patterns in urban settings

This paper describes how a Geographic Information System (GIS) is being used to help estimate multi-class truck flows in an urban setting. Emphasis is placed on the reasons why this approach is valuable, the specific GIS tools and techniques employed, the value added by employing a GIS-based approach, and the results being obtained. These findings are generalized to describe the benefits that might be expected in other situations where a similar modeling approach is used.     

Toward criteria in the development of urban transportation systems

Improved criteria are necessary to aid in determining awards of federal funds for metropolitan transit projects. Commuting is the main use for public transit. Thus a primary objective of an urban transit system should be to provide a flexible and balanced set of options to the workers in the metropolitan area for their journey to work. This paper discusses various facets of an appropriate balance among the three modes: rapid rail, bus, and automobile. Three cities are selected for further analysis: Baltimore, Kansas City, and Phoenix. These cities represent different stages in economic-transportation development, and also present different spatial patterns of residence and employment. The applicability of rapid rail transit to each city is examined in view of central city worker concentration and recent trends.     

Travel demand in the US urban areas: A system dynamic panel data approach

Using panel data from 85 urban areas over a 20-year period and applying a system panel data approach, this paper examines the relationship between travel demand in terms of per-capita VMT and urban spatial characteristics. Regression results show that road density and urban spatial size have positive and statistically significant effects on travel demand in the US urban areas. Urban population density and urban congestion have negative and statistically significant effects on travel demand.     

Assessing network vulnerability of heavy rail systems with the impact of partial node failures

Much of the literature in recent years has examined the vulnerability of transportation networks. To identify appropriate and operational measures of nodal centrality using connectivity in the case of heavy rail systems, this paper presents a set of comprehensive measures in the form of a Degree of Nodal Connection (DNC) index. The DNC index facilitates a reevaluation of nodal criticality among distinct types of transfer stations in heavy rail networks that present a number of multiple lines between stations. Specifically, a new classification of transfer stations—mandatory transfer, non-mandatory transfer, and end transfer—and a new measure for linkages—link degree and total link degree—introduces the characteristics of heavy rail networks when we accurately expose the vulnerability of a node. The concept of partial node failure is also introduced and compare the results of complete node failure scenarios. Four local and global indicators of network vulnerability are derived from the DNC index to assess the vulnerability of major heavy rail networks in the United States. Results indicate that the proposed DNC indexes can inform decision makers or network planners as they explore and compare the resilience of multi-hubs and multi-line networks in a comprehensive but accurate manner regardless of their network sizes.

     

Home-to-work commuting,urban form and potential energy savings: A local scale approach to regional statistics

The link between transport energy consumption and land use patterns has been the focus of a considerable amount of academic works over the past decades. While many empirical researches are backed up with solid statistical techniques, most of them do not fully consider the influence of scale underlying empirical quantitative investigations. Using fine-scale home-to-work commuting data for Wallonia (Belgium), this paper re-evaluates Breheny’s (1995) assertion that urban structure should hold the characteristics of major cities if substantial energy savings are to be achieved. A local scale approach highlights efficient settlements in terms of transport energy consumption not only within major towns, but also within remote rural areas. Furthermore, results suggest that influencing the urban form following local energy efficient examples rather than regional ones could also yield significant gains, without an extreme policy stance of re-urbanisation in major cities.     

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.     

Towards improving resilience of cities: an optimisation approach to minimising vulnerability to disruption due to natural disasters under budgetary constraints

Transportation - In recent years, climate change emerged as a dominant concern to many parts of the world bringing in huge economic losses disturbing normal business/life. In particular cities are...     

A novel approach for systematically calibrating transport planning model systems

Calibration of a transport planning model system is a complex process. While trial-and-error methods and modelling expertise are still the backbone of calibration of transport models, analytical approaches automating the calibration process can improve the accuracy of the models. Introducing a model to guide modellers in the calibration process of large-scale transport planning model systems is the core of this study, where a systematic model for choosing the most appropriate models and parameters is discussed. The effectiveness of the proposed model is investigated by comparing three scenarios which are built on the Travel/Activity Scheduler for Household Agents model as a large-scale agent-based model system.

     

Evaluating security of rail transit systems: A metric system approach

Crime and fear of crime is a major problem plaguing U.S. transit systems, particularly those serving large urban areas. This paper presents a normative framework for assessing rail transit security following a system-wide metric approach. The security metric can also be used to assess the marginal improvement in security as a result of improving or adopting alternative policing and monitoring strategies. The model consists of five tasks: surveying rail transit security systems, developing a rail transit security metric, assigning efficiency ratings to rail security functions, developing a composite index for the efficiency of the overall security system, and applying a probability matrix to temper the results. Efficiency ratings can be translated into probability of occurrence figures that can be used in a decision tree context to improve rail transit security.     

长距离水平冻结法在广州地铁中的应用与实践

广州地铁二号线中山纪念堂～越秀公园区间隧道的南端穿越清泉街断裂破碎带,该破碎带由南北侧的破碎带和中间挤压带组成,长度达145 m.隧道施工通过该破碎带时采用了全断面水平冻结法作为辅助施工方法,冻结施工总长度115 m,冻结管单管长度最长达62 m,而目前国内外水平冻结的长度仅45 m.文章对该冻结施工方案的产生过程作了回顾,并结合广州地区气候特点和工程地质特点,详尽地分析了长距离水平冻结施工技术在广州地铁清泉街断裂破碎带地层中应用的可行性.