隆纳铁路沱江特大桥水中基础施工

隆纳铁路沱江特大桥全长581．03m，主桥为一联(48 80 48)m预应力混凝土连续箱梁，5#、6#水中墩为大桥主墩，本文介绍了5#墩和6#墩水中基础施工方案的选择，并介绍了5#墩基础采用的万能杆件格架编织袋围堰施工及6#墩采用的双壁钢围堰环形封底施工。     

大冲邕江特大桥承台钢套箱围堰施工关键技术

大冲邕江特大桥为不对称双塔三跨连续高低塔混凝土斜拉桥,桥塔承台长19．6m,宽18．5m,承台厚6m,采用双壁钢套箱围堰施工。文章介绍钢套箱围堰计算及施工技术,为同类桥梁提供借鉴参考。     

城际铁路S型曲线桥移动模架的应用与研究

当前,随着我国城际铁路建设规模的快速增长,尤其在山地施工需要解决的复杂工况非常多。本文结合重庆轨道交通十号线一期工程高架段5种墩型(2.6 m×2.6m^4.5 m×7.5 m)、多种跨径(30m、35m、40m)连续箱梁的施工实例,详细阐述MSS40zx-1100型自行式移动模架的设计构造及关键技术的创新应用。本方法较好地解决了能同时适应多跨径、多墩型、半径500m以下S型曲线桥现浇连续箱梁施工中的技术问题。     

矮塔斜拉桥单根可换式斜拉索施工过程控制技术

矮塔斜拉桥(又称部分斜拉桥)主要以塔矮、梁刚、索集中的特点,在外观上类似普通斜拉桥,而在受力区别于施工技术方面,它更接近连续刚构(连续梁)桥,大桥造型美观、造价经济合理。本文以主跨65m+108m+65m双塔单索面三跨预应力混凝土矮塔斜拉桥工程为背景,同时为矮塔斜拉桥的施工技术进行剖析,为以后类似工程提供参考经验。     

洪屋涡特大桥主墩承台施工

洪屋涡特大桥主墩承台采用单薄壁钢套箱围堰的方法。介绍1号主墩承台套箱设计、拼装下放及拆除的施工技术。     

矮塔斜拉桥单根可换式斜拉索施工过程控制技术

矮塔斜拉桥(又称部分斜拉桥)主要塔矮、梁刚、索集中的特点;在外观上类似普通斜拉桥,而在受力区别与施工技术方面,它更接近连续刚构(连续梁)桥,大桥造型美观、造价经济合理。本文以主跨65m+108m+65m双塔单索面三跨预应力混凝土矮塔斜拉桥为工程背景,同时为矮塔斜拉桥的施工技术进行部析,为以后类似工程提供参考经验。     

平潭海峡大桥主桥承台钢套箱设计与施工工艺研究

依托平潭海峡大桥主桥承台施工工程,结合所处海域水文特点,介绍了主墩、交界墩钢套箱设计的结构、工况,并阐述了钢套箱安装方法,封底砼握裹力,承台浇筑次数选择等施工工艺,为承台钢套箱设计与施工提供可参考的经验。     

排架式桥墩墩梁固结合理墩高的研究

采用一联5孔30m T梁模型,按不同墩高分别研究桥墩的受力情况,分析出设置刚构墩的合理墩高。本文对桥梁设计具有一定的实际指导作用。     

高塔型矮塔斜拉桥总体设计研究

以某市桥梁工程为例,了解项目概况,探讨桥梁方案与总体布置情况,该桥为（108+180+108）m双塔单索面混凝土矮塔斜拉桥,主桥为塔梁固结的结构体系,墩梁采用支座连接;项目位于城市周边开发区,考虑城市景观需要,采用高塔型矮塔斜拉桥,其兼具斜拉桥的美观性和矮塔斜拉桥的经济性及施工便利性;索塔塔冠为尖型拱顶造型的建筑风格,塔身也配以景观雕刻;斜拉索采用扇形单索面布置,通航孔上方主梁跨中段采用等截面设计。分析主桥设计,提出该桥施工方案,以供参考。     

紫阳汉江特大桥主墩深水钢吊箱静动力分析

钢吊箱结构整体与局部应力计算和稳定性分析是桥梁深水施工的关键。文章借助大型通用有限元结构分析软件ANSYS8．1,采用空间梁单元Beam188单元和空间壳单元Shell63单元建立紫阳汉江特大桥主墩深水钢吊箱的空间有限元模型,对该钢吊箱进行静力和动力分析,为紫阳汉江特大桥主墩深水施工提供参数依据。     

New evidence on walking distances to transit stops: identifying redundancies and gaps using variable service areas

The percentage of the population being served by a transit system in a metropolitan region is a key system performance measure but depends heavily on the definition of service area. Observing existing service areas can help identify transit system gaps and redundancies. In the public transit industry, buffers at 400 m (0.25 miles) around bus stops and 800 m (0.5 miles) around rail stations are commonly used to identify the area from which most transit users will access the system by foot. This study uses detailed OD survey information to generate service areas that define walking catchment areas around transit services in Montreal, Canada. The 85th percentile walking distance to bus transit service is found to be around 524 m for home-based trip origins, 1,259 m for home-based commuter rail trip origins. Yet these values are found to vary based on our analysis using two statistical models. Walking distances vary based on route and trip qualities (such as type of transit service, transfers and wait time), as well as personal, household, and neighbourhood characteristics. Accordingly, service areas around transit stations should vary based on the service offered and attributes of the people and places served. The generated service areas derived from the generalized statistical model are then used to identify gaps and redundancies at the system and route level using Montreal region as an example. This study can be of benefit to transport engineers and planners trying to maximize transit service coverage in a region while avoiding oversupply of service.     

秦岭马白山隧道新型紧急救援站结构型式研究北大核心CSCD

针对艰险山区高速铁路隧道的防灾救援难题,文章依托秦岭马白山隧道,提出了适合该隧道的新型紧急救援站结构型式,并利用FDS软件模拟隧道内纵向通风时列车着火后的烟气扩散,确定了规范中尚未给出的紧急救援站隔离区长度参数。结果表明:(1)秦岭马白山隧道新型紧急救援站结构型式应包括疏散区、隔离区以及待避救援区;(2)利用FDS数值模拟时,在不考虑纵向通风下,烟气沿下坡方向的扩散长度为295 m;考虑沿下坡方向通风时烟气最远扩散长度为980 m,建议隔离区长度设置为1000 m。     

Establishing speed–flow–density relationships for exclusive motorcycle lanes

Abstract

The motorcycle is a popular mode of transport in Malaysia and developing Asian countries, but its significant representation in the traffic mix results in high rates of motorcycle accidents. As a result, the Malaysian Government decided to segregate motorcycle traffic along its new federal roads as an engineering approach to reduce accidents. However, traffic engineers needed to know the maximum traffic a motorcycle lane could accommodate. Despite substantial literature related to speed–flow–density relationships and capacities of various transport facilities, there is a knowledge gap regarding motorcycle lanes. This paper establishes motorcycle speed–flow–density relationships and capacities of exclusive motorcycle lanes in Malaysia. Observations of motorcycle flows and speeds were conducted along existing and experimental motorcycle lanes. Motorcycle speed–density data were aggregated and plotted for two types of observable motorcycle riding behaviour patterns that were influenced by the widths of a motorcycle lane: the headway pattern (lane width ≤ 1.7 m) and the space pattern (lane width > 1.7 m). For both riding patterns, regression analysis of motorcycle speed–density data best fits the logarithmic model and consequently the motorcycle flow–density and speed–flow models are derived. Motorcycle lane capacities for headway and space riding patterns are estimated as 3300 mc/hr/lane and 2200 mc/hr/m, respectively.     

特长隧洞TBM施工通风系统设计

以辽宁大伙房水库输水隧洞工程为背景,详细设计了TBM2标段独头掘进9 km的施工通风系统,选取了漏风系数、摩阻系数等特征参数,计算了风量、风压和通风功率,并对通风设备及其布置进行了优化匹配。在世界上首次采用了每段长度为300 m的2.2 m通风软管,取得了很好的通风效果。     

The impact of urban rail transit on commercial property value: New evidence from Wuhan,China

The interaction between rail transit and the urban property market is a vital foundation for planning transit-based policy such as Value Capture and Transit Oriented Development (TOD). Yet only few studies have reported the impact of transit access on commercial property value. This paper presents empirical evidence from Wuhan, China, to enrich the knowledge in the subject area. Spatial autoregressive models were employed to estimate the commercial value capture, based on 676 observations along Wuhan’s metro rail line through the main business districts. Value appreciation was discovered within the 400 m radius of road network distance from Metro stations. The transit access premiums present as two tiers: 16.7% for the 0–100 m core area and approximately 8.0% within the 100–400 m radius. The result demonstrates the potential benefit of adopting value capture and optimising TOD planning to support sustainable urban rail transit investment. Amid rapid urbanisation in China, the evidence reported here could help better inform cities, across the developing world and beyond, of the benefits of adopting rail transit-based policy.     

Travel demand estimation risk for high‐speed railway transport considering travel price competition

The Hokkaido Shinkansen (HS) bullet train line is under consideration to open in 2020. In this study, travel demand is estimated for the HS. Because some explanatory variables that are used for such estimation can have estimation errors, travel demand estimation risk is also calculated. In addition, because the HS can compete with airlines for modal share, the impacts of travel price competition (TPC) on the travel demand and the demand estimation risk are also estimated. In this study, the travel demand estimation risk is measured as the variance or the SD of the stochastic travel demand. The analysis reveals the following: the modal share of HS is 16% less when TPC is considered than when it is not considered; TPC causes the travel demand estimation risk to decrease; the probabilities of the HS operating at a deficit with and without consideration of TPC are calculated as 31.2% and 1.25%, respectively, and the increase in the mean consumer surplus accruing from the HS is calculated as JPY 47bn/year ($US588m/year) without TPC and as JPY 66bn/year ($US825m/year) with TPC. Copyright © 2012 John Wiley & Sons, Ltd.     

A method for measuring accurate traffic density by aerial photography

Traffic density can be accurately measured by counting the number of vehicles within 1 km; however, it is often calculated between macroscopic traffic parameters using the fundamental equation because of difficulty of observing traffic density directly in the field. Measuring density in this way may be inaccurate and may bias the analysis because the relationship between these traffic parameters can vary across the study sites. The purpose of this study is to find a method for measuring traffic density from aerial photography that is easy and accurate, and for this purpose, we investigated whether the measuring length (i.e., the length of a section of roadway from which observations of traffic are simultaneously collected) can be shorter than 1 km and yet retain the same measured traffic density. We divided an aerial photograph into several 20‐m unit sections, counted the number of vehicles manually, and examined measured traffic density according to central limit theory. According to the results of this study, with the number of 20‐m unit sections for observing traffic density at 15 (the measuring length is 300 m), the measured traffic density was almost the same as the density of a representative section of 1 km. Copyright © 2014 John Wiley & Sons, Ltd.     

Validation of an agent-based microscopic pedestrian simulation model in a crowded pedestrian walking environment

This study validates a recently developed agent-based pedestrian micro-simulation model in a crowded walking environment. The model is applied to simulate pedestrian movements at a major street in the downtown Vancouver area. The street was closed for traffic to allow people attending a social event to leave the area safely. The calibration of model parameters is conducted using a Genetic Algorithm that minimizes the error between simulated and actual trajectories, acquired by means of computer vision. Validation results confirm the accuracy of the simulated trajectories, as the average error between the actual and simulated trajectories is found to be 0.28?m, and the average error in walking speed is just 0.06 m/s. Furthermore, results show that the model is capable of reproducing the actual behavior of pedestrians during different interactions with high accuracy (more than 94% for most interactions).     

Urban transportation modeling: The discussion continues

This article is a response to John Polak's article, entitled, A Comment on Supernak's Critique of Transport Modeling, published elsewhere in this issue of TRANSPORTATION. It offers necessary clarifications to the issues discussed in an earlier article in this journal (Supernak, 1983). It also responds to the philosophical issues discussed in Polak's article, such as the nature of transport phenomena, and the role, form and methodology of transport modeling.     

Effects of the Los Angeles transit strike on highway congestion

In this paper we investigate the effect of the Los Angeles transit strike on highway congestion through analysis of highway sensor data, using both a before-and-after comparison, and a control group comparison. We found that average 5:00 a.m. to 10:00 p.m. traffic speeds declined by as much as 20% during the strike, and the average length of the rush period increased by as much as 200%, even though increases in traffic were small, despite the fact that transit riders constitute a small fraction of the traveling population. Speeds declined the most at locations upstream from the places where queues normally end. We believe that highways are especially susceptible to congestion during strikes because travelers have little opportunity to adjust and equilibrate their travel patterns, as is possible during ordinary periods of traffic growth.