LOCATING EMPLOYMENT GROWTH IN URBAN AREAS TO MINIMIZE TRAVEL TIME

The transportation requirements of an urban area are, in part, a function of its land use pattern. Reducing travel in an urban area by effective land use design appears to be a worthwhile public policy objective. The planning model derived in this article uses as its core the matrix version of the Lowry model developed by Garin. The model allocates basic employment to the zones of an urban area in order to minimize work and service trips. A hypothetical planning problem for Metropolitan Toronto illustrates use of the model.     

Do suburban residents prefer the fastest or low-carbon travel modes? Combining public participation GIS and multimodal travel time analysis for daily mobility research

Sustainability of urban transportation and residents' daily mobility is increasingly important for the future of urban regions. In this paper, we present a novel methodology combining mapped survey responses (gathered using public participation GIS) and sophisticated multimodal routing analysis to understand patterns of suburban residents' daily mobility. Our particular focus is on residents' mode choices and their optimality in terms of travel time. We also examine the carbon-intensity of potential mode choice mismatches where a comparatively slower travel mode is chosen for a particular trip. This paper shows how the combination of the two data sources create new possibilities for analysing daily mobility by enabling the comparison of self-reported, geographically referenced mobility patterns and modelled, objectively “optimal” patterns. Our case study results from a rapidly growing metropolitan area, Greater Helsinki in Finland, indicate that people have rather sustainable daily mobility practices. Their daily trips are typically short (median 1.8 km), and non-motorised travel modes are the most popular. Also the share of car travel is significant. While public transport clearly has the lowest modal share, it is frequently used on longer trips to destinations where public transport connections are good (particularly the city centre). In 44% of trips, the respondents choose the fastest travel mode. When a comparatively slower travel mode is chosen, it most often produces less CO₂ emissions than the fastest mode. However, particularly on shopping trips – the most commonly reported type of trip – car driving dominates as the fastest means of transportation. When a slower mode is chosen on a shopping trip, it is typically more carbon-intensive than the fastest mode would have been in that case. The methodology presented here can be used to support local decision making, particularly when daily services and transport infrastructure are planned or reorganised.     

基于GPS数据的海岛型目的地游客时空行为相似性研究————以山东长岛为例

通过爬取GPS轨迹记录平台的轨迹数据,采用季节强度指数、核密度分析、近邻分析等方法对山东长岛游客时空行为进行相似性探讨,研究表明：① 年内,在气候要素影响下,海岛型目的地季节强度指数更高;日内,轨迹数量的“双峰”结构和轨迹长度的“三峰”结构都表明游客出行时间和轨迹长度有强相似性和集中性,且行程结束时间相对更晚;② 空间上,交通的不可直达性和时间的限制性造成游客在岛屿选择上高度集中,空间轨迹相似度很高,呈现典型的“轴状”和“环状”集聚结构,“向海”和“亲海”特征突出;③ 游客在海岛上的流动形成典型的等级分层结构和节点分散分布特征,重要节点对旅游流网络的控制作用明显;④ 与其他类型目的地相比,景区的核心作用在海岛上不够突出,受景区进入率不高的影响,游客在旺季期间与本地居民在公共交通设施和公共休闲空间的使用上重叠率较高,是造成旅游旺季部分路段和休闲空间过度拥挤的核心原因。     

Unplanned urban growth: land use/land cover change in the Guwahati Metropolitan Area,India

Unplanned urban growth, particularly in developing countries has led to changes in land use/land cover (LULC). Numerous Indian cities face problems of unplanned LULC change due to nominal or non-existent planning efforts compounded by rapid urban population growth. The Guwahati Metropolitan Area (GMA) is one such urban centre. The present study assesses the trajectories of LULC change using Landsat imageries acquired in 1976, 1989, 2002 and 2015. Natural and semi natural vegetated area and artificial and natural water bodies decreased while built-up areas, cultivated and managed areas, and natural and semi natural non-vegetated areas increased. The built-up area increased from 23.9 in 1976 to 115.1 km² in 2015 becoming the dominant land cover class accounting for 41.8% of the total geographical area. During this period, natural and semi natural vegetated land were reduced by 88.9 km² at an annual rate of 2.2 km². Over the years there was an increasing trend of built-up land and cultivated and managed areas in the peripheral areas of the city while natural and semi natural vegetated land diminished. Consequently, as in many other developing countries, there is an urgent need for the governmental authorities and other stakeholders to implement effective urban planning policies.     

基于社会网络理论的旅游系统空间结构优化研究

基于交通网络和旅游资源禀赋的旅游系统空间结构研究具有一定欠缺性。借鉴Shih研究成果,基于旅游者行走游线和旅游流量,分析社会网络理论的程度中心性、接近中心性和中介中心性3个指标作为衡量区域旅游进出通道和中心性、可进入性和旅游集散中心的意义,将目的地划分为区域旅游核心区、缓冲区和边缘区,并对区域旅游分工和设施配备要求提供理论指导。旅游核心区应配备旅游中心、信息中心和口岸交通设施,旅游缓冲区应加强旅游景区建设,旅游边缘区在加强景区建设的同时还应强化宣传工作。探讨旅游系统空间结构的影响因素及其优化措施,并对福建进行实证研究。     

居民家庭日常出行碳排放的发生机制与调控策略——以北京市为例

根据2007年北京市居民活动日志调查数据,利用Amos7.0软件建立单效标因素的路径分析模型,试图在"社区-家庭"层面上挖掘"空间利用-出行特征-碳排放"的内在发生机理,藉此寻找城市空间组织低碳化的调控路径。研究发现:影响居民家庭日常出行碳排放的主要因素是出行距离和出行方式。社区空间利用特征对家庭出行的距离总量有显著影响,对小汽车出行比率则没有明显作用效果;私家车的购置对居民家庭出行行为的高碳化具有不可逆的作用特点;在现有设施条件、空间环境和车辆使用政策下,公共交通对私人交通出行没有替代性。研究认为,城市空间组织和调控优化应通过土地混合利用、设施供给等物质空间组织与再组织手段,形成空间行为组织和行为规划策略,引导居民降低交通发生量,优化居民交通发生的时空结构,建构低碳的城市空间结构。     

CostMAP: an open-source software package for developing cost surfaces using a multi-scale search kernel

ABSTRACT

Cost surfaces are a crucial aspect of route optimization and least cost path (LCP) calculations and are used in awide range of disciplines including computer science, landscape ecology, and energy-infrastructure modeling. Linear features present akey weakness to traditional routing calculations along cost surfaces because they cannot identify whether moving from acell to its adjacent neighbors constitutes crossing alinear barrier (increased cost) or following acorridor (reduced cost). Following and avoiding linear features can drastically change predicted routes. We introduce an approach to address this adjacency issue using asearch kernel that identifies these critical barriers and corridors. We have built this approach into anew Java-based open-source software package– CostMAP (cost surface multi-layer aggregation program)– which calculates cost surfaces and cost networks using the search kernel. CostMAP allows users to input multiple GIS data layers and to set weights and rules for developing aweighted-cost network. We compare CostMAP performance with traditional cost surface approaches and show significant performance gains– both following corridors and avoiding barriers– by modeling the movement of alarge terrestrial animal– the Baird’s Tapir (Tapirus bairdii)– in amovement ecology framework and by modeling pipeline routing for carbon capture and storage (CCS).     

Sensitivity of tsunami evacuation modeling to direction and land cover assumptions

Although anisotropic least-cost-distance (LCD) modeling is becoming a common tool for estimating pedestrian-evacuation travel times out of tsunami hazard zones, there has been insufficient attention paid to understanding model sensitivity behind the estimates. To support tsunami risk-reduction planning, we explore two aspects of LCD modeling as it applies to pedestrian evacuations and use the coastal community of Seward, Alaska, as our case study. First, we explore the sensitivity of modeling to the direction of movement by comparing standard safety-to-hazard evacuation times to hazard-to-safety evacuation times for a sample of 3985 points in Seward's tsunami-hazard zone. Safety-to-hazard evacuation times slightly overestimated hazard-to-safety evacuation times but the strong relationship to the hazard-to-safety evacuation times, slightly conservative bias, and shorter processing times of the safety-to-hazard approach make it the preferred approach. Second, we explore how variations in land cover speed conservation values (SCVs) influence model performance using a Monte Carlo approach with one thousand sets of land cover SCVs. The LCD model was relatively robust to changes in land cover SCVs with the magnitude of local model sensitivity greatest in areas with higher evacuation times or with wetland or shore land cover types, where model results may slightly underestimate travel times. This study demonstrates that emergency managers should be concerned not only with populations in locations with evacuation times greater than wave arrival times, but also with populations with evacuation times lower than but close to expected wave arrival times, particularly if they are required to cross wetlands or beaches.     

基于GIS与地理探测器的旅游地空间分布格局及驱动力分析——以贵州为例

以贵州旅游地空间数据为基础,运用平均最邻近、地理探测器等方法,研究贵州1990—2018年4个时间截面旅游地空间格局,分析该时期旅游重心演化进程,探讨旅游地与地理环境、社会经济要素间关系并开展驱动力分析。结果表明：① 4个时期旅游地均为凝聚状态分布,总体呈现点、团向面状、带状聚集转变;② 全省旅游收入演化比客流量演化更为敏感和剧烈,二者均以经向变幅为主导,且呈现西部比重大于东部的态势;③ 旅游地在海拔高程垂向上表现为近似正态分布,碳酸盐岩类区旅游地资源多为自然类景点、碎屑岩类区主要表现为民族文化类景点的聚集分布,断层线5 km缓冲区范围内分布90%左右的旅游地、其空间展布总体与断层线走向吻合,三叠、寒武及二叠地层是旅游地的主要分布区,旅游地沿省道特征分布明显;④ 全省旅游地分布主要受旅游地到河流沟谷距离、县级行政中心距离、高速公路直线距离、陆上交通路网密度、高速公路路网密度、断层线距离、河流沟谷密度等7项因子驱动;而距河流沟谷、距县级行政中心、距高速公路直线距离以及交通路网密度水平等因子的组合效应集中控制了当前贵州旅游地空间分布的总体格局。     

Time series forecasting of river flow using an integrated approach of wavelet multi-resolution analysis and evolutionary data-driven models. A case study: Sebaou River (Algeria)

The complexity of hydrological processes and lack of data for modeling require the use of specific tools for non-linear natural phenomenon. In this paper, an effort has been made to develop a conjunction model – wavelet transformation, data-driven models, and genetic algorithm (GA) – for forecasting the daily flow of a river in northern Algeria using the time series of runoff. This catchment has a semi-arid climate and strong variability in runoff. The original time series was decomposed into multi-frequency time series by wavelet transform algorithm and used as inputs to artificial neural networks (ANN) and adaptive neuro-fuzzy inference system (ANFIS) models. Several factors must be optimized to determine the best model structures. Wavelet-based data-driven models using a GA are designed to optimize model structure. The performances of wavelet-based data-driven models (i.e. WANFIS and WANN) were superior to those of conventional models. WANFIS (RMSE = 12.15 m³/s, EC = 87.32%, R = .934) and WANN (RMSE = 15.73 m³/s, EC = 78.83%, R = .888) models improved the performances of ANFIS (RMSE = 23.13 m³/s, EC = 54.11%, R = .748) and ANN (RMSE = 22.43 m³/s, EC = 56.90%, R = .755) during the test period.     

Critical distances: Comparing measures of spatial accessibility in the riverine landscapes of Peruvian Amazonia

Quantitative measures of accessibility are increasingly used in land cover change modeling and in assessing human pressure on the environment. In riverine Amazonia the significance of physical accessibility for biodiversity, land use patterns and economic livelihoods is widely acknowledged, but attempts to quantify accessibility in practice have been few in number. In this study we compare different distance- and frequency-based measures of spatial accessibility and develop a quantitative model of accessibility patterns for the north-eastern Peruvian Amazonia where rivers form the core of the transportation network. We model accessibility between the rural areas of the Loreto region and the capital city of Iquitos, using different distance algorithms in a geographic information system, and complement the distance model with information on river boat frequencies and transport capacities. Patterns of accessibility are visualized in terms of potential production zones for different types of agricultural and non-timber forest products.This study demonstrates how results from different accessibility measures vary considerably. The mean Euclidean distance to Iquitos is almost 270 km, the mean network distance nearly 760 km and the mean travel time 70 h. Observed network distances from validation points to Iquitos are on average 1.6 times longer than Euclidean distances, and for the whole study area, the average ratio between modeled network distances and Euclidean distances is 3.1. The correlation between network distances and time distances is very strong, but time distances are relatively shorter along the major channels where boat traffic is considerably faster than along narrow, tightly meandering rivers. Measures of boat frequency and transport capacity show that availability of transport possibilities is highly varying across the region. These measures provide insights into the ’thickness’ of trade, indicating the level of market integration for riverine settlements. We conclude that quantifying accessibility in an environment like Peruvian Amazonia requires measures that take into account the spatial structure and dynamic nature of the riverine transportation network. Time as a unit of distance provides the most relevant measure of accessibility in the Amazonian context, where many human actions and traditional livelihoods are controlled by travel times between the regional core and the hinterland.     

Identifying primary public transit corridors using multi-source big transit data

ABSTRACT

Effective public transit planning needs to address realistic travel demands, which can be illustrated by corridors across major residential areas and activity centers. It is vital to identify public transit corridors that contain the most significant transit travel demand patterns. We propose a two-stage approach to discover primary public transit corridors at high spatio-temporal resolutions using massive real-world smart card and bus trajectory data, which manifest rich transit demand patterns over space and time. The first stage was to reconstruct chained trips for individual passengers using multi-source massive public transit data. In the second stage, a shared-flow clustering algorithm was developed to identify public transit corridors based on reconstructed individual transit trips. The proposed approach was evaluated using transit data collected in Shenzhen, China. Experimental results demonstrated that the proposed approach is a practical tool for extracting time-varying corridors for many potential applications, such as transit planning and management.     

新冠肺炎疫情前后游客出行行为的时空特征研究——以中国香港为例

新型冠状病毒肺炎疫情对香港旅游业产生了巨大的冲击,掌握疫情期间游客出行的时空变化特征,对后疫情时代旅游业复苏和发展至关重要。本文基于2019年和2020年社交媒体的旅游评论数据,采用时序统计、复杂网络分析等方法,对比分析疫情前后香港旅游网络的演化特征,并结合旅游目的地语义刻画游客出行规律。结果表明：(1)游客出行规律呈现出一定程度变化,与疫情前相比,游客在一次出游行程中所访问的旅游目的地数量大幅下降;(2)热门目的地仍然在香港旅游网络中承担着连接其他目的地的重要作用,而围绕热门目的地形成的旅游网络社区由疫情前的空间显著集聚转为相对稀疏分布,但网络社区内部目的地的空间分布较疫情前变得更加集聚;(3)在游客选择出行目的地方面,热门目的地访问量急剧减少,而以往游客较少且地理位置较为偏僻的目的地,在游客出行目的地选择时变得更被关注,但产业目的地始终是香港旅游中最热门的旅游目的地类型。     

A Nationwide Comparison of Driving Distance Versus Straight-Line Distance to Hospitals

Many geographic studies use distance as a simple measure of accessibility, risk, or disparity. Straight-line (Euclidean) distance is most often used because of the ease of its calculation. Actual travel distance over a road network is a superior alternative, although historically an expensive and labor-intensive undertaking. This is no longer true, as travel distance and travel time can be calculated directly from commercial Web sites, without the need to own or purchase specialized geographic information system software or street files. Taking advantage of this feature, we compare straight-line and travel distance and travel time to community hospitals from a representative sample of more than 66,000 locations in the fifty states of the United States, the District of Columbia, and Puerto Rico. The measures are very highly correlated (r ² > 0.9), but important local exceptions can be found near shorelines and other physical barriers. We conclude that for nonemergency travel to hospitals, the added precision offered by the substitution of travel distance, travel time, or both for straight-line distance is largely inconsequential.     

广州市地铁可达性时空演化及其对公交可达性的影响

应用GIS方法,选取2000、2003、2009和2012年4个时间节点,运用复杂网络理论构建了广州市公共交通网络模型,通过对比分析地铁站点与线路加入到公共交通网络中所产生的变化,定量分析地铁网络建设对公共交通可达性的影响,分析地铁发展不同时期内,城市公共交通可达性空间格局的演化,全面探讨地铁建设对城市公共交通可达性的影响,以期为一体化的多模式城市公共交通体系发展决策提供理论支持。结果显示:①广州市地铁网络顺利完成由树状向回路网络的转变,地铁可达性重心与广州市空间扩展方向呼应,呈现出向南、向东迁移特征;②地铁在很大程度上提高了广州城市公交网络可达性,且其改善作用随地铁线路网的增加和回路网络的发育而日益显著;③地铁网络对城市公交可达性格局的影响,打破了常规公交网络圈层式公交可达性格局,逐渐呈现出圈层式加沿地铁线路分布的廊道式格局;④地铁对公交各站点网络可达时间的影响,常规公交站点可达时间变化程度呈现出由地铁线路向外递减的空间分布趋势,当地铁网络发育形成回路网络时,大大地提升公交网络的运营效率,缩短各个站点之间的出行时间。     

“Is there any time left for walking?” Physical activity implications of suburban commuting in the Barcelona metropolitan region

ABSTRACT

The present study delves into the explanatory factors of the walking patterns of residents in metropolitan regions, who tend to be pressed for time when travelling to their daily destinations or activities. We particularly focus on the effects of the commuting distance on the amount of walking that can be achieved, which has health, socioeconomic and environmental implications. This study confirms the potential benefits of using smartphone tracking data to examine walking patterns. To enable this, a smartphone tracking application was developed to obtain accurate mobility data from a group of adults (n = 93) residing in the Barcelona Metropolitan Region (Spain) and have to commute to a suburban university campus that can only be reached by using motorized transport modes. The results highlight the commuting distance and employment status as strong determinants of the amount of walking time achieved by this study group. Moreover, it was determined that among transit users, the commuting distance of male commuters was negatively associated with walking when compared with female transit users, whereas explanatory factors for private transport users bore insignificant results. Smartphone devices proved their potential as an effective and useful source of data in transportation and health research.     

Aging in Activity Spaces: How Does Individual Accessibility Compare across Age Cohorts?

The proportion of individuals age sixty-five and over is growing at an astronomical rate in the United States, and some estimate that this demographic age group will double by the year 2025. Older adults and adults nearing retirement age tend to reside in suburban neighborhoods and rely heavily on personal vehicles. This study uses travel diary data on automobile trips to construct activity spaces to explore whether or not travel patterns across age groups result in differential access to particular goods and services in the Orlando Metropolitan Statistical Area (MSA). Using an approach based on time geographic density estimation, this research identifies activity spaces across different age cohorts to identify differences in the automobility of different age groups. Results indicate that the geographic dispersion of activities with the Orlando MSA currently favors younger adults. Adults age fifty to sixty-four had the lowest accessibility scores compared to other age cohorts. If this preretirement group has poor access now, holding other effects constant, their access might only get worse as they get older and stop commuting. Transportation is an important consideration in planning for aging populations, and analyzing differences in how older adults travel compared to their younger counterparts can offer insight into the diverse needs of this group. Key Words: accessibility, aging populations, mobility, time geography, transportation.     

Investigating the system dynamics technique for the modeling and simulation of the development of spatial data infrastructures

Spatial data infrastructure (SDI) is a complex system for which huge investments are being made worldwide. These large-scale investments in the development of SDIs incontrovertibly require reliable design and planning that guarantee a successful outcome. One approach to deal with such an expectation is to model the development process of the SDI system over time. If the model can be translated into the computer-based environment to be used as a virtual world, then the real situation can also be simulated. Such a simulation will enable the SDI coordinators/managers to gain knowledge about the behavior of the system under different decisions and situations and eventually help them to better develop the SDI through the informed decision making. However, a limited number of tools and techniques are currently available in the SDI modeling history in terms of the modeling and simulation of such a complex system. The system dynamics technique based on systems theory is a method for modeling and managing the feedback systems that are complex, dynamic and nonlinear over time. This article addresses the applicability of the system dynamics technique for modeling and simulating the development process of SDIs. It is argued that the system dynamics technique is capable of modeling the interactions among the factors affecting the SDI, the feedback loops and the delays. It is also highlighted that an SDI model based on the system dynamics technique enables the SDI coordinators/managers to simulate the effect of different factors or decisions on various aspects of SDI and evaluate alternative decisions and/or policies prior to making any commitment.     

Interest in intermediate soft-classified maps in land change model validation: suitability versus transition potential

This study compares two types of intermediate soft-classified maps. The first type uses land use/cover suitability maps based on a multi-criteria evaluation (MCE). The second type focuses on the transition potential between land use/cover categories based on a multi-layer perceptron (MLP). The concepts and methodological approaches are illustrated in a comparable manner using a Corine data set from the Murcia region (2300 km², Spain) in combination with maps of drivers that were created with two stochastic, discretely operating, commonly used tools (MCE in CA_MARKOV and MLP in Land Change Modeler). The importance of the different approaches and techniques for the obtained results is illustrated by comparing the specific characteristics of both approaches by validating the suitability versus transition potential maps to each other using a Spearman correlation matrix and, between the Corine maps, using classical ROC (receiver operating characteristic) statistics. Then, we propose a new use of ROC statistics to compare these intermediate soft-classified maps with their respective hard-classified maps of the models for each category. The validation of these results can be beneficial in choosing a suitable model and provide a better understanding of the implications of the different modeling steps and the advantages and limitations of the modeling tools.     

A unified approach for location-allocation analysis: integrating GIS,distributed computing and spatial optimization

Location-allocation modeling is an important area of research in spatial optimization and GIScience. A large number of analytical models for location-allocation analysis have been developed in the past 50 years to meet the requirements of different planning and spatial-analytic applications, ranging from the location of emergency response units (EMS) to warehouses and transportation hubs. Despite their great number, many location-allocation models are intrinsically linked to one another. A well-known example is the theoretical link between the classic p-median problem and coverage location problems. Recently, Lei and Church showed that a large number of classic and new location models can be posed as special case problems of a new modeling construct called the vector assignment ordered median problem (VAOMP). Lei and Church also reported extremely high computational complexity in optimally solving the best integer linear programming (ILP) formulation developed for the VAOMP even for medium-sized problems in certain cases.

In this article, we develop an efficient unified solver for location-allocation analysis based on the VAOMP model without using ILP solvers. Our aim is to develop a fast heuristic algorithm based on the Tabu Search (TS) meta-heuristic, and message passing interface (MPI) suitable for obtaining optimal or near-optimal solutions for the VAOMP in a real-time environment. The unified approach is particularly interesting from the perspective of GIScience and spatial decision support systems (DSS) as it makes it possible to solve a wide variety of location models in a unified manner in a GIS environment. Computational results show that the TS method can often obtain in seconds, solutions that are better than those obtained using the ILP-based approach in hours or a day.