广州市城市公共停车场发展政策研究

为从交通政策层面上积极推进广州市城市公共停车场的建设,引导其健康、有序发展,在分析了广州市现行停车政策现状及问题的基础上,从法律法规建设、相关鼓励政策、停车收费政策、投资模式等方面介绍了国内外城市公共停车场发展政策。最后,提出适合广州市公共停车场发展的政策建议,并强调停车发展政策只有由单纯以需求为导向的适应性政策转向有利于停车需求管理的引导性政策发展,才能适应城市交通可持续发展的要求。     

Error and optimism bias in toll road traffic forecasts

Traffic forecasts are employed in the toll road sector, inter alia, by private sector investors to gauge the bankability of candidate investment projects. Although much is written in the literature about the theory and practice of traffic forecasting, surprisingly little attention has been paid to the predictive accuracy of traffic forecasting models. This paper addresses that shortcoming by reporting the results from the largest study of toll road forecasting performance ever conducted. The author had access to commercial-in-confidence documentation released to project financiers and, over a 4-year period, compiled a database of predicted and actual traffic usage for over 100 international, privately financed toll road projects. The findings suggest that toll road traffic forecasts are characterised by large errors and considerable optimism bias. As a result, financial engineers need to ensure that transaction structuring remains flexible and retains liquidity such that material departures from traffic expectations can be accommodated.

走航式适航水深测量误差来源及准确度检测

走航式适航水深测量是目前港口工程测量提出的新课题,对其测量精度的评定和准确度的检验尤为重要。从两个方面论述了适航水深测量误差来源及消除或削弱方法,给出了精度估算公式,并进行了测量精度估算,给出了适航水深测量的检测方法。     

一种对称式激光位移传感器

激光位移传感器作为一种非接触式测量工具,它属于一种比较先进的测量方法,但由于使用条件变化多、使用环境苛刻等诸多因素而降低了激光位移传感器的检测精度。本文通过对传统激光位移传感器在检测过程中存在的问题及解决办法分析,提出了一种对称式激光位移传感器。该传感器结构合理、使用方便、可减少甚至消除由于成像光斑不均匀或不对称产生的测量误差,从而有效地提高测量精度。     

一种新的沥青混凝土路面坑洞热修补工艺方法及补坑装置

结合国内外现有的沥青混凝土路面坑洞修补工艺,分析了传统坑洞修补工艺方案及其结构型式.按永久性修补要求提出了一种采用静力热压法的新的坑洞热修补工艺方法,同时设计出了一种新的坑洞修补装置,并通过室内坑洞热修补模拟试验,证明所提方法的可行性和有效性.     

Safety assessment for a side-by-side offloading mooring system

In order to improve the safety properties of an offloading system with side-by-side (SBS) mooring in which the FPSO is moored by a yoke system in the field of BZ25-1, it is necessary to analyze those properties. According to the experience of similar projects, tow strategies of different offloading arrangements were discussed by using the 3-D radiation/diffraction theory and quasi-static time domain method to assess their respective safety properties. Through the safety assessment analysis of different arrangement comparisons, various ways to improve the safety properties of offloading systems with side-by-side mooring were verified by analyzing the tension in the mooring lines and the fender deflection. Through comparison it can be concluded that by enlarging the key factors properly, including the size of the fenders and the hawsers as well as the number of hawsers, a better safety performance can be achieved.     

大跨径多塔斜拉桥非线性静力分析

以一座在建的多塔结合梁斜拉桥为工程背景,运用大型有限元结构分析软件ANSYS,建立多塔斜拉桥的空间非线性有限元模型,考虑拉索垂度效应、结构大位移和梁柱效应3种几何非线性因素,进行了大跨度多塔斜拉桥空间非线性静力分析,给出了桥梁结构主梁、桥塔以及斜拉索的位移及内力云图,结果表明：多塔斜拉桥的主跨跨中位移变形最大,为33.2 cm;边塔弯矩随高度的变化各不相同,塔底弯矩最大;斜拉索的最大索力在边塔外侧的辅助墩附近。     

城市轻轨钢轨道梁静载试验研究

简要介绍了城市轻轨钢轨道梁在工厂内进行静荷载试验的方法和步骤,同类工程具有借鉴意义。     

特大吨位桥桩承载力试验研究

采用自平衡试桩法对润扬长江公路在桥特大吨位大直径基桩进行了足尺模型竖向载力试验，同时在同一场进行了2极小直径模拟桩试验，将自平衡试桩结果转换成等效传统静载试桩曲线并进行分析研究，对模拟试桩效果进行了有意义的探索，介绍了自平衡试桩法的双荷载箱技术在世业洲高架桥大吨位基桩中的应用。     

When is big data big enough? Implications of using GPS-based surveys for travel demand analysis

A number of studies in the last decade have argued that Global Positioning Systems (GPS) based survey offer the potential to replace traditional travel diary surveys. GPS-based surveys impose lower respondent burden, offer greater spatiotemporal precision and incur fewer monetary costs. However, GPS-based surveys do not collect certain key inputs required for the estimation of travel demand models, such as the travel mode(s) taken or the trip purpose, relying instead on data-processing procedures to infer this information. This study assesses the impact that errors in inference can have on travel demand models estimated using data from GPS-based surveys and proposes ways in which these errors can be controlled for during both data collection and model estimation. We use simulated datasets to compare performance across different sample sizes, inference accuracies, model complexities and estimation methods. Findings from the simulated datasets are corroborated with real data collected from individuals living in the San Francisco Bay Area, United States. Results indicate that the benefits of using GPS-based surveys will vary significantly, depending upon the sample size of the data, the accuracy of the inference algorithm and the desired complexity of the travel demand model specification. In many cases, gains in the volume of data that can potentially be retrieved using GPS devices are found to be offset by the loss in quality caused by inaccuracies in inference. This study makes the argument that passively collected GPS-based surveys may never entirely replace surveys that require active interaction with study participants.