Forecasting ridership for a metropolitan transit authority

The recent volatility in gasoline prices and the economic downturn have made the management of public transportation systems particularly challenging. Accurate forecasts of ridership are necessary for the planning and operation of transit services. In this paper, monthly ridership of the Metropolitan Tulsa Transit Authority is analyzed to identify the relevant factors that influence transit use. Alternative forecasting models are also developed and evaluated based on these factors—using regression analysis (with autoregressive error correction), neural networks, and ARIMA models—to predict transit ridership. It is found that a simple combination of these forecasting methodologies yields greater forecast accuracy than the individual models separately. Finally, a scenario analysis is conducted to assess the impact of transit policies on long-term ridership.     

呼和浩特市客运出租汽车数量预测模型研究

一个城市的客运出租市场是否需要投放出租汽车和投放数量的多少,不仅影响服务质量,也影响每位出租汽车经营者的自身利益,从而影响整个．出租汽车行业的稳定与健康发展。本文对出租汽车影响较大的因素进行了统计和相关性分析,确定了自变量,采用回归模型和曲线拟合的方法建立了未来年份的出租汽车数量预测模型,预测结果和往年历史数据对比表明,时间变量的一元线性模型和实际值较接近;幂函数曲线的预测值增加较快,就呼和浩特市的具体情况,幂函数曲线的预测效果较好。本文给出了适合呼和浩特市区的出租汽车发展趋势和合理的数量预测。     

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.

路基边坡坡面冲刷稳定性的模糊综合评判方法

基于边坡冲刷稳定性有较大的随意性和不确定性,文章利用模糊数学理论,对坡面冲刷进行分级模糊综合评判,为边坡坡面冲刷稳定性综合评价提供了一条新的途径。     

盾构下穿越已运营隧道的地表变形实测分析

文章基于盾构理论依据,结合上海市轨道交通7号线沪南路-白杨路区间隧道监测实际,对双线盾构下穿越已运营隧道施工引起的地表变形规律进行了探讨,分析盾构隧道下穿越施工引起土体移动的影响因素,为今后同类工程的设计与施工提供参考。     

矩形顶管施工引起地表变形的实测分析

顶管施工会对周围土体产生扰动,引起土体移动。而相对于圆形顶管,矩形顶管对周围土体的扰动更大,从而引起的地表变形也更大。文章结合工程实例,对矩形顶管施工引起的地表变形规律进行了探讨,分析矩形顶管施工引起土体移动的影响因素,为同类工程的设计与施工提供参考。     

Runoff and soil erosion from highway construction spoil deposits: A rainfall simulation study

To measure soil loss from these road construction spoils, 30 rainfall simulations involving five rainfall intensities were conducted to study runoff and soil erosion processes on a road in China. Twenty-five of the rainfall simulations were carried out on loose materials five different slopes. Another five rainfall simulations were conducted on compacted road materials with a slope of 30.6%. The results show that soil bulk density has a positive effect on runoff rate, and the effect of slope on runoff rate changes with rainfall intensity. Higher soil bulk density increases soil loss under low rainfall intensity, but decreases soil loss when rainfall intensity is high. Soil loss is positively related to slope, but the relationship differs from that in prior studied of croplands and disturbed lands. Equations for predicting soil erosion from loose materials and compacted road are developed.     

山区河湾路基边坡颗粒起动条件与抗冲刷坡度计算

根据山区河湾路基边坡冲刷特点,建立路基边坡上填料单颗粒三维受力模式,对凹岸路基路边坡填料颗粒冲刷起动的基本条件进行理论推导。通过算例结果分析,探讨不同水流近底流速条件下的凹岸路基边坡抗冲稳定坡度。     

Strategic planning support for road safety measures based on accident data mining

When actions and measures to increase road safety are to be planned by the police and local authorities, it is necessary to consider the specific accident circumstances as well as their historical, current, and predicted course. In particular, combinations of accident circumstances not contained in existing police statistics are often neglected, but may nevertheless be relevant, e. g., due to an increasing frequency. In order to identify these undiscovered interesting combinations, we propose a framework to support strategic planning of road safety measures based on several consecutive data mining stages. The scope, type, and location of road safety measures must be planned at a strategic level several months in advance to be fully effective. Therefore, it is essential to investigate and predict the accident circumstances and the temporal changes in their frequency comprehensively. Only with the knowledge, e. g., about the temporal pattern, locations, conditions of roads or speeds, meaningful actions can be derived. The embedded data mining approaches, i. e., frequent itemset mining, time series clustering, time series classification, forecasting, and scoring, are carefully selected, coordinated, and aligned. As a result, the framework provides police users with information about circumstances of accidents that are of interest in the future and presents their previous temporal and local patterns in a dashboard. In this study, the framework is applied in four different geographical regions. Thereby, default parameter settings for all approaches are found that are particularly suitable for the framework to investigate novel geographic regions.     

沉埋式双排抗滑桩加固滑坡承载机理研究

为探究沉埋式双排抗滑桩(沉埋式后排桩和全长式前排桩的组合形式)的承载机理,采用土压力盒和应变片完成一系列室内模型试验,在外界施加的滑坡推力作用下,量测桩身内力变化与桩周土体压力的变化情况,研究桩身受力的分布形式和土拱效应,并分析后排桩长度变化时的双排桩的受力变化规律。研究结果表明,沉埋式双排抗滑桩的受力方式不同于全长双排抗滑桩的受力方式:沉埋式抗滑桩前排桩桩后推力分布形式为梯形分布,桩前抗力分布形式为矩形分布;后排桩桩后推力分布形式呈梯形分布,桩前抗力分布形式为倒梯形分布。后排桩的沉埋深度对前排桩的土拱效应有着较大的影响,并且分析认为当前后排桩承载比较接近时的沉埋深度为设计沉埋深度。为进一步探究排距对沉埋深度的影响,运用FLAC3D,探讨不同排距下双排桩的承载比。研究结果表明,随着排间距增大,后排桩的设计沉埋深度逐渐减小。