空间句法及其在城市交通研究领域的应用

空间句法提供了一套量化描述空间结构的方法,开拓了一个理解复杂城市交通系统的崭新视角。文章阐述了空间句法的创立背景、核心理论和模型构建方法;详细介绍了空间句法在轨道交通枢纽TOD开发评价、行人步行交通研究、城市空间路网结构合理性分析等城市交通研究方向上的应用,对其在城市交通规划领域的应用前景进行展望。     

Determining transit nodes for potential transit-oriented development: Along the LRT corridor in Addis Ababa,Ethiopia

The aim of transit-oriented development (TOD) is to create a livable urban environment by improving the integration between land-use and transportation systems. The capital city of Ethiopia, Addis Ababa, aims to promote a sustainable transportation system by launching its first light rail transit (LRT) network to control the current pattern of increased congestion and the need for mass transport. Planning for TOD around existing transit stations helps achieve improved transit choice and encourages local economic development. Therefore, this article proposes a methodology to quantitatively measure the existing TOD in terms of a TOD index within the walkable distance of transit nodes by measuring the criteria that define TOD levels. The TOD index is calculated for areas of 22 stations on the East-West LRT line of Addis Ababa. Depending on the value of the TOD index, certain stations are identified to have a potential TOD but poor transit accessibility. With these results, the recommendation to improve TOD planning can become accurate for each station, depending on its relevant factors. Such results also help identify each station's potential for TOD planning and its improvements toward future local developments.     

Random Process Model for Urban Traffic Flow Using a Wavelet‐Bayesian Hierarchical Technique

Abstract: The existing well‐known short‐term traffic forecasting algorithms require large traffic flow data sets, including information on current traffic scenarios to predict the future traffic conditions. This article proposes a random process traffic volume model that enables estimation and prediction of traffic volume at sites where such large and continuous data sets of traffic condition related information are unavailable. The proposed model is based on a combination of wavelet analysis (WA) and Bayesian hierarchical methodology (BHM). The average daily “trend” of urban traffic flow observations can be reliably modeled using discrete WA. The remaining fluctuating parts of the traffic volume observations are modeled using BHM. This BHM modeling considers that the variance of the urban traffic flow observations from an intersection vary with the time‐of‐the‐day. A case study has been performed at two busy junctions at the city‐centre of Dublin to validate the effectiveness of the strategy.     

Bi-level Programming Formulation and Heuristic Solution Approach for Dynamic Traffic Signal Optimization

Abstract:   Although dynamic traffic control and traffic assignment are intimately connected in the framework of Intelligent Transportation Systems (ITS), they have been developed independent of one another by most existing research. Conventional methods of signal timing optimization assume given traffic flow pattern, whereas traffic assignment is performed with the assumption of fixed signal timing. This study develops a bi-level programming formulation and heuristic solution approach (HSA) for dynamic traffic signal optimization in networks with time-dependent demand and stochastic route choice. In the bi-level programming model, the upper level problem represents the decision-making behavior (signal control) of the system manager, while the user travel behavior is represented at the lower level. The HSA consists of a Genetic Algorithm (GA) and a Cell Transmission Simulation (CTS) based Incremental Logit Assignment (ILA) procedure. GA is used to seek the upper level signal control variables. ILA is developed to find user optimal flow pattern at the lower level, and CTS is implemented to propagate traffic and collect real-time traffic information. The performance of the HSA is investigated in numerical applications in a sample network. These applications compare the efficiency and quality of the global optima achieved by Elitist GA and Micro GA. Furthermore, the impact of different frequencies of updating information and different population sizes of GA on system performance is analyzed.     

Automated extraction and classification of thunderstorm and non-thunderstorm wind data for extreme-value analysis

Design wind loads are partly based on extreme value analyses of historical wind data, and limitations on the quantity and spatial resolution of wind data pose a significant challenge in such analyses. A promising source of recent wind speed and direction data is the automated surface observing system (ASOS), a network of about 1000 standardized US weather stations. To facilitate the use of ASOS data for structural engineering purposes, procedures and software are presented for (a) extraction of peak gust wind data and thunderstorm observations from archived ASOS reports, (b) classification of wind data as thunderstorm or non-thunderstorm to enable separate analyses, and (c) construction of data sets separated by specified minimum time intervals to ensure statistical independence. The procedures are illustrated using approximately 20-year datasets from three ASOS stations near New York City. It is shown that for these stations thunderstorm wind speeds dominate the extreme wind climate at long return periods. Also presented are estimates based on commingled data sets (i.e., sets containing, indiscriminately, both non-thunderstorm and thunderstorm wind speeds), which until now have been used almost exclusively for extreme wind speed estimates in the US. Analyses at additional stations will be needed to check whether these results are typical for locations with both thunderstorm and non-thunderstorm winds.     

医院更新的整体性思维--以苏州大学第一附属医院为例

我国医院目前正经历着经济体制、医学模式和技术革命的三大变革,这促使传统医院的更新建设无论在性质和目标,还是内容和方式上都发生重大变化。本文以苏州大学第一附属医院的更新规划为例,从功能与空间、结构与动线、情感与自然、现状与未来这四个方面进行整体研究,探讨相关问题。     

Calibrating Rail Transit Assignment Models with Genetic Algorithm and Automated Fare Collection Data

Recently, automated fare collection (AFC) systems using smart card technology have become the main method for collecting urban rail transit (URT) fares in many cities around the world. Transaction data obtained through these AFC systems contain a large amount of archived information including how passengers use the URT system, and thus can be used in calibrating assignment models for precise passenger flow calculation. We present a methodology for calibrating URT assignment models using AFC data. The calibration approach uses a genetic algorithm‐based framework with nonparametric statistical techniques. Three initial numerical tests show that the proposed approach finds more reasonable solutions than traditional approaches for the calibrated parameters. Furthermore, after calibration by the proposed approach, the existing assignment model delivers more accurate calculations of passenger flows in the network.     

信号交叉口车辆排队统计方法研究

信号交叉口排队控制的关键在于排队统计.以排队检测器和感应检测器为硬件基础,检测进口车辆排队状态,设计排队统计逻辑对采集的实时信息做出规整,建立排队统计方法,为信号机提供准确的路口排队信息,提高排队控制效果.应用Vissim交通仿真软件对排队统计策略进行仿真分析,结果表明,交叉口排队信息优化了配时方案,减少了绿灯损失时间、停车次数和延误,完善了智能交通控制效果.     

TOD模式在福州市的应用浅析

以较小的资源投入、较小的环境代价,最大可能的满足日益增长的交通需求,这一可持续发展城市交通系统的目标决定了从长远看必须建设以公共交通为主体的城市综合交通运输体系,TOD模式是实现以公共交通为主体的城市综合交通系统的重要途径.本文简要介绍了TOD模式的概念、特征及其发展概况,并系统分析了公交引导城市发展的模式(TOD)在福州市区中的应用。     

A GIS-Based Traffic Signal Coordination and Information Management System

Abstract: This paper discusses research conducted at the Georgia Institute of Technology that investigated the use of geographic information system (GIS) technology as a tool in traffic signal information management and signalized intersection coordination. TRANSYT-7F is the most widely used and respected computer model for optimizing the coordination of traffic signals. Unfortunately, creating an optimal TRANSYT-7F model is very costly. The hypothesis of this research was that using a specialized GIS in conjunction with TRANSYT-7F could enhance the process of coordinating a traffic signal system. The research resulted in the development of a GIS-based traffic signal coordination and information system that operates on a microcomputer. This system is an improvement over existing TRANSYT-7F models because relationships between intersections do not have to be encoded manually. Instead, the system takes advantage of the GIS's topologic data structure, which provides these relationships. The process of analyzing different network optimization scenarios is simplified with this system because the user need only to select intersections to be coordinated from the GIS graphic display rather than cutting and pasting from existing input files. Alternatively, the system can serve as a multipurpose signal information system and play a vital role in decision support. It can provide improved access to signal data and allows for swift identification of intersections that experience excessive delays or unacceptable levels of service.     

基于TOD的西安城市公共交通发展战略

在发展可持续交通的需求下,针对西安市的城市交通现状,提出了轨道主导型TOD策略,并分析了轨道主导型TOD对城市布局的影响,基于TOD的城市布局对西安市交通的优化作用,最后阐述了以轨道交通为主体的公共交通一体化战略。     

Wavelet Packet-Autocorrelation Function Method for Traffic Flow Pattern Analysis

Abstract:   Accurate and timely forecasting of traffic flow is of paramount importance for effective management of traffic congestion in intelligent transportation systems. A detailed understanding of the properties of traffic flow is essential for building a reliable forecasting model. The discrete wavelet packet transform (DWPT) provides more coefficients than the conventional discrete wavelet transform (DWT), representing additional subtle details of a signal. In wavelet multiresolution analysis, an important decision is the selection of the decomposition level. In this research, the statistical autocorrelation function (ACF) is proposed for the selection of the decomposition level in wavelet multiresolution analysis of traffic flow time series. A hybrid wavelet packet-ACF method is proposed for analysis of traffic flow time series and determining its self-similar, singular, and fractal properties. A DWPT-based approach combined with a wavelet coefficients penalization scheme and soft thresholding is presented for denoising the traffic flow. The proposed methodology provides a powerful tool in removing the noise and identifying singularities in the traffic flow. The methods created in this research are of value in developing accurate traffic-forecasting models .     

Signal timing at an isolated intersection under mixed traffic environment with self-organizing connected and automated vehicles

This study provides a signal timing model for isolated intersections under the mixed traffic environment consisting of connected and human-driven vehicles (CHVs) and connected and automated vehicles (CAVs). Different from existing studies, CAVs are not controlled by traffic controllers and conduct trajectory planning themselves, which are called self-organizing CAVs (SOCAVs). The specific trajectory planning strategies of SOCAVs are not accessible to traffic controllers either. The signal optimization problem is formulated as a mixed integer linear programming (MILP) model for total vehicle delay minimization. The states of SOCAVs and CHVs passing the stop bar are predicted without prior information of the trajectory planning strategies of SOCAVs. SOCAVs can lead approaching platoons to pass the intersection effectively, and such “leading effects” of SOCAVs are utilized. Phase sequence and duration are optimized with the “structure-free” phasing scheme. A parallel particle swarm optimization algorithm with a grouping strategy is designed to solve the optimization model at a reduced scale for computational efficiency. Numerical studies validate that (1) the proposed algorithm significantly outperforms the benchmark method, which directly solves the proposed MILP model using the solver Gurobi 9.0, under medium and high traffic demand; and (2) the proposed model significantly outperforms fixed-time and vehicle-actuated signal control in terms of vehicle delay and throughput. Sensitivity analysis shows that the SOCAV penetration rate of 30% is sufficient to guarantee satisfactory performance of the proposed signal timing model.     

An Implementation of the Mode-Split Traffic-Assignment Method

A software called Optimal Traffic Signal Control System (OTSCS) was developed by us for testing the feasibility of dynamically controlling a traffic signal by finding optimal signal timing to minimize delay at signalized intersections. It also was designed as a research tool to study the learning behavior of artificial neural networks and the properties of heuristic search methods. It consists of a level-of-service evaluation model that is based on an artificial neural network and a heuristic optimization model that interacts with the level-of-service evaluation model. This article discusses the latter model, named the Optimal Traffic Signal Timing Model (OTSTM). The OTSTM was applied to determine optimal signal timing of two-phase traffic signals to evaluate the model's performance. Two search methods were employed: a depth-first search method (an enumeration method) and a direction-search method that the authors developed. It was found that the OTSTM with the direction search resulted in "optimal" signal timings similar to the depth-first search, which would always produce a global optimal timing. Yet the cost of the direction search, as measured by the CPU time of the computer used for analysis, was found to be much less than the cost of obtaining an optimal solution by the depth-first search cases—more than 10 times less. The study showed that once the artificial neural network is properly trained, heuristic optimal signal timing combined with artificial networks can be used as a decision-support tool for dynamic signal control. This article demonstrates how OTSTM can quickly find an optimal signal-timing solution for two-phase traffic signals.     

以公共交通为导向的土地利用模式研究

面临城市化和机动化的双重挑战,该文先对城市土地利用与交通系统之间的基本关系进行了分析,并在引进国外相关理论和实践的基础上,对TOD产生的背景、发展历程、一般模式作了较为系统的分析。最后以西安市为例进行了示例分析,指出在中国实施TOD的优势与不足,并提出了中国公共交通导向的城市土地开发策略建议。     

土地利用与城市交通协调发展--近代美国"TOD"理论与实践的研究

本文通过分析近代美国的“TOD”理论及其实践创作,对“TOD”的发展模式和实践效果进行了比较详细的阐释.“TOD”理论倡导在区域层面上整合土地利用和公共交通系统,这样有助于提高公共交通使用率,减少私人汽车的出行,抑制城市的无序蔓延.我国人口多,能源与土地资源相对匮乏,而目前城市化,机动化进程正在逐步加快,只有利用“TOD”发展模式,才能保证城市的可持续发展.     

Analysing real world data streams with spatio-temporal correlations: Entropy vs. Pearson correlation

Smart Cities use different Internet of Things (IoT) data sources and rely on big data analytics to obtain information or extract actionable knowledge crucial for urban planners for efficiently use and plan the construction infrastructures. Big data analytics algorithms often consider the correlation of different patterns and various data types. However, the use of different techniques to measure the correlation with smart cities data and the exploitation of correlations to infer new knowledge are still open questions. This paper proposes a methodology to analyse data streams, based on spatio-temporal correlations using different correlation algorithms and provides a discussion on co-occurrence vs. causation. The proposed method is evaluated using traffic data collected from the road sensors in the city of Aarhus in Denmark.     

轨道交通TOD地区的步行尺度

轨道交通TOD站点地区确定规划圈层边界的重要依据之一是步行尺度,即步行距离形成的半径,但不同城市的TOD地区步行尺度并不相同。步行距离虽然能指导划定圈层边界和影响范围,但对步行决策起主导作用的则是步行时间,二者按照"时间-距离"换算关系相互关联,并受到地形条件、空间布局、交通环境等步行环境要素的制约。TOD地区步行尺度的差异是由于步行时间、步行距离和步行环境差异所造成的。对TOD地区步行尺度的差异及原因进行总结,可以为我国TOD地区规划确定合理的步行尺度及TOD模型提供有益的借鉴思路。     

Research on New Urban Area Planning Based on TOD Mode:A Study on Binhu New District of Hefei City

As an urban development mode,the TOD (Transit-oriented Development) mode,targeted at energy-saving and based on the public transportation system,has positive significance for solving problems like disordered urban sprawl and traffic congestion in Chinese cities.This article takes Binhu New District of Hefei as an example to illustrate the practice of the TOD mode in the urban design of large and medium-sized cities.The paper analyzes the relationship between the new district,central urban area,and public transportation development,and puts forward that the TOD mode is suitable for Bihu New District.It states that the TOD mode can be realized through methods such as the building of a "double-rapid" comprehensive public transportation network,the setting up of decentralized-compact urban clusters and TOD communities,the mixevd land-use,as well as the scenery design with complete walking space.The paper also proposes that certain flexible methods can be adopted in order to promote the TOD mode,including making full use of bus transit when rail transit is lacked,setting up TOD communities surrounding the transport hubs,etc.     

蒙特利尔地下城的行人动态、布局和经济影响

尽管地下系统被广泛认为是蒙特利尔中央商务区的一个重要经济推动力，但是地下系统开发并没有一个总体规划或如何评估扩建提案的共识。为了给地下空间开发找到更系统的方法，本文调查了地下系统中行人流量水平所带来的经济影响，对以前的数据（Zacharias．2000）作了更新。文章结合了三套数据：综合行人流量调查数据与1996年和2003年更新后的房地产使用调查数据。这项调查显示出．在这种封闭的步行系统中，系统设计和由此产生的行人流量是如何与经济行为相关的．