西部地区公路地质灾害监测预报技术研究

“西部地区公路地质灾害监测预报技术研究”项目针对西部地区公路地质灾害危险性区划、滑坡、崩塌与泥石流监测预报及地质灾害安全管理等关键技术问题进行深入系统研究,形成了公路滑坡、崩塌与泥石流监测预报成套技术,建立了公路地质灾害数据标准,构建了“基于GIS的公路地质灾害监测预报信息系统”平台,实现了公路地质灾害监测实时分析处理和动态预报,为地质灾害综合管理提供技术支撑。     

公路限速标志设置的位置研究

公路限速标志是现代交通管理中最普遍的控制车速的方式,也是保障道路交通安全的基础设施。文章介绍了限速标志设置的基本要求,分析了我国限速标志设置存在的问题,并从限速标志设置的地点、路段、位置点、距离和限速值等方面论证限速标志设置的位置,为科学设置公路限速标志提供参考。     

西部地区公路快速客运系统关键技术研究

本篇依托＂西部地区公路快速客运系统关键技术研究＂项目,介绍了公路快速客运的概念、构成要素、服务对象、特征、发展现状及存在的主要问题,指出了公路快速客运系统的车辆、站场、服务、管理、信息等方面的关键技术,形成了公路快速客运系统评价模型,并提出了相应的快速客运发展对策及建议,为我国西部地区的公路快速客运系统建设与发展提供参考依据。     

桂林至柳州高速公路改扩建项目限速方案分析

文章结合桂林至柳州高速公路改扩建项目老路运行现状,采取调查、计算等手段,进行运行速度预测,综合考虑道路线形等因素,确定速度限制值,提出了分路段、分车型相结合的限速方案,以期提高项目通行效率和行车安全性.     

三江源高寒地区省道曲麻莱至不冻泉公路的建设实践

通过在三江源高寒地区建设曲麻莱至不冻泉公路,从项目决策、规模标准、建设管理、实施效果及相关问题的研究,谈在三江源高寒地区进行公路建设的体会.     

浅议水毁防治措施选择

公路水毁灾害在我国西部地区频繁发生,然而,防护措施的选择却多凭经验办事。因此,文章在国内外现有研究成果的基础上,通过对西部地区的实地调研,全面分析水毁形态与成因机理,阐述了不同公路水毁防治措施的防护机理,结合水毁防护措施自身的强度和经济性,提出了各种水毁防护措施的适用条件。这对我国公路水毁预防和治理具有一定理论与实践意义。     

西部公路建设中的生态环境保护

1 引言我国西部地区10个省(市)区,面积545万平方公里,人口2.93亿, 2001年GDP1.45万亿元。公路运输是西部地区的主要运输方式。改革开放20多年来,公路基础设施有了很大进步,但仍是制约西部发展的主要因素,为适应我国西部大开发战略的要求,中央已明确提出加强西部地区交通基础设施建设“近期要以公路建设为重点”,“必须从战略眼光出发,下更大的决心,以更大的投入,先行建设,适当超前”。为此,交通部制定了西部地区公路发展的总体目标。用20年左右的时间,使西部地区公路交通的面貌发生根本性变化,基本建成布局合理、功能完善的公路运输服务…     

公路石质边坡防护与环境保护研究

西部交通建设科技项目＂公路石质边坡防护与环境保护的研究＂在确定公路石质边坡地质条件因子、环境条件因子及评价指标的基础上,运用人工神经网络方法对公路石质边坡的地质条件因子、环境条件因子进行了评价分析,形成了公路石质边坡防护与环境保护信息系统及技术指南。本篇对该项目的主要研究内容、实施方案、成果及其使用情况进行介绍,为我国公路石质边坡防护与环境保护工作提供参考依据。     

《西部地区公路瓦斯隧道设计与旋工技术研究》达到国际先进水平

日前，由四川省交通运输厅公路规划勘察设计研究院等单位承担的2007年度西部交通建设科技项目《西部地区公路瓦斯隧道设计与施工技术研究》通过鉴定验收，鉴定专家认为该项目研究成果总体达到了国际先进水平。     

基于设计速度与运行速度理念在山区高速公路限速设计中的优化应用研究

为探究山区高速公路优化限速设计方法,多方面分析设计速度、运行速度、限制速度和事故风险等因素,从相对“静态”和“动态”的限速设计思路提出山区高速公路设计限速方法的应用优化建议,有利于提高公路运行安全,并为管理单位提供相关参考依据。     

关于我国内河船舶污染强制责任 保险限额的研究Ⅰ ——国内外船舶污染强制保险责任限额的设置研究

本文是财政部基本科研业务费专项项目“港口近岸生态环境损害评价方法及生态修复技术研究”的研究成果。为建立适合我国国情的内河船舶污染强制责任保险限额的制定方法,文章通过分析国内外船舶污染责任保险限额设定内容、设定方式和设定依据,明确其设定思路并分析其优缺点,进一步确定我国内河船舶污染责任保险限额的的法律依据,比较责任限额的科学设置方法。在“限额设置区间、区间递进方式、限额变动、起始吨位、使用货币、责任限额的确定方式、对责任限制的免除条件、法律基础”等方面进行了理论创新,提出详细的可操作性设置建议。     

建议速度的定义及应用价值

文章介绍建议速度的定义,阐述了建议速度标志的设置范围,并从提高设计速度、降低公路建造成本、提高公路通过率、避免速度陷阱与公路乱罚款、提高公路管理水平、减少交通事故、节能环保等方面探讨了建议速度的应用价值及意义。     

Analysis of a cooperative variable speed limit system using microscopic traffic simulation

Variable speed limit systems where variable message signs are used to show speed limits adjusted to the prevailing road or traffic conditions are installed on motorways in many countries. The objectives of variable speed limit system installations are often to decrease the number of accidents and to increase traffic efficiency. Currently, there is an interest in exploring the potential of cooperative intelligent transport systems including communication between vehicles and/or vehicles and the infrastructure. In this paper, we study the potential benefits of introducing infrastructure to vehicle communication, autonomous vehicle control and individualized speed limits in variable speed limit systems. We do this by proposing a cooperative variable speed limit system as an extension of an existing variable speed limit system. In the proposed system, communication between the infrastructure and the vehicles is used to transmit variable speed limits to upstream vehicles before the variable message signs become visible to the drivers. The system is evaluated by the means of microscopic traffic simulation. Traffic efficiency and environmental effects are considered in the analysis. The results of the study show benefits of the infrastructure to vehicle communication, autonomous vehicle control and individualized speed limits for variable speed limit systems in the form of lower acceleration rates and thereby harmonized traffic flow and reduced exhaust emissions.     

Going fast or going green? Evidence from environmental speed limits in Norway

This paper studies the impact of speed limits on local air pollution using a series of date-specific speed limit reductions in Oslo over the 2004–2011 period. We find that lowering the speed limit from 80 to 60 km/h reduces travel speed by 5.8 km/h. However, we find no evidence of reduced air pollution as measured next to the treated roads. Our estimates suggest an annual time loss of the speed limit reductions of 66 USD per affected vehicle. Our findings imply that policy makers need to consider other actions than speed limit reductions to improve local air quality.     

Effects of low speed limits on freeway traffic flow

Recent years have seen a renewed interest in Variable Speed Limit (VSL) strategies. New opportunities for VSL as a freeway metering mechanism or a homogenization scheme to reduce speed differences and lane changing maneuvers are being explored. This paper examines both the macroscopic and microscopic effects of different speed limits on a traffic stream, especially when adopting low speed limits. To that end, data from a VSL experiment carried out on a freeway in Spain are used. Data include vehicle counts, speeds and occupancy per lane, as well as lane changing rates for three days, each with a different fixed speed limit (80 km/h, 60 km/h, and 40 km/h). Results reveal some of the mechanisms through which VSL affects traffic performance, specifically the flow and speed distribution across lanes, as well as the ensuing lane changing maneuvers. It is confirmed that the lower the speed limit, the higher the occupancy to achieve a given flow. This result has been observed even for relatively high flows and low speed limits. For instance, a stable flow of 1942 veh/h/lane has been measured with the 40 km/h speed limit in force. The corresponding occupancy was 33%, doubling the typical occupancy for this flow in the absence of speed limits. This means that VSL strategies aiming to restrict the mainline flow on a freeway by using low speed limits will need to be applied carefully, avoiding conditions as the ones presented here, where speed limits have a reduced ability to limit flows. On the other hand, VSL strategies trying to get the most from the increased vehicle storage capacity of freeways under low speed limits might be rather promising. Additionally, results show that lower speed limits increase the speed differences across lanes for moderate demands. This, in turn, also increases the lane changing rate. This means that VSL strategies aiming to homogenize traffic and reduce lane changing activity might not be successful when adopting such low speed limits. In contrast, lower speed limits widen the range of flows under uniform lane flow distributions, so that, even for moderate to low demands, the under-utilization of any lane is avoided. These findings are useful for the development of better traffic models that are able to emulate these effects. Moreover, they are crucial for the implementation and assessment of VSL strategies and other traffic control algorithms.     

The 55mph speed limit on US roads: comments on Godwin and Kulash's analysis

There is probably no way to evaluate the impact of the 55 mph limit in 1974 objectively—the necessary data were never collected. Godwin and Kulash assume a current saving of 3000 lives per year. This number is not the objective result of some explicit procedure, but rather the judgement of two conscientious experts; it is not subject to replication by other experts. Furthermore, the quality of their estimate is limited by the quality of the historical studies they are using for input: those studies relied on ‘best guesses’ because they did not have the necessary basic data. No amount of heroic effort by Godwin and Kulash can overcome these inherent deficiencies.

It is almost as difficult to quantify the benefits of the 55 mph limit today. The regression results reported above find no statistically discernible relation between average speed and the fatality rate, though they do show a significant relationship between speed‐variance and the fatality rate. Given this result, we want to know the relationship between the 55 mph limit and speed variance. There is weak evidence that this critical relationship is negative—raising the speed limit a small amount might actually decrease the dispersion of highway speeds.

Whatever the benefits of the 55 limit, its costs are important. On the rural interstate highways it costs about 250 years of extra driving time to save one life. And the policing resources spent on enforcing the 55 mph limit would save more lives if they were allocated to other highway safety measures.     

Prioritizing new bicycle facilities to improve low-stress network connectivity

This paper introduces a new method to prioritize bicycle improvement projects based on accessibility to important destinations, such as grocery stores, banks, and restaurants. Central to the method is a new way to classify “bicycling stress” using marginal rates of substitution which are commonly developed through empirical behavioral research on bicyclist route choice. MRS values are input parameters representing bicycling stress associated with the number of lanes and speed limit of a street. The method was programmed as a geographic information system tool and requires commonly available data. The tool is demonstrated on three improvement scenarios that were recently proposed for Seattle, Washington. The full build-out scenario consists of 771 projects that include various new bike lanes, protected bike lanes, and multi-use trails. The tool produces priority rankings based on a project’s ability to improve low-stress connectivity between homes and important destinations. The analysis identifies specific areas and neighborhoods that can be expected to exhibit better bikeability. Transportation planners can use the tool to help communicate anticipated project impacts to decision-makers and the public.     

雾天高速公路限速模型研究

文章通过对传统的基于停车视距和基于交通标志视认距离的雾天高速公路限速模型的分析,提出了考虑比较全面的组合限速模型,并采用保守分析与乐观分析方法对各种限速模型的计算结果进行比较,论证各种限速模型的特点和适用条件,同时还提出了不同能见度条件下的高速公路限速值和管理措施,为高速公路雾天行车安全管理提供借鉴。     

Accounting for dynamic speed limit control in a stochastic traffic environment: A reinforcement learning approach

This paper proposes a novel dynamic speed limit control model accounting for uncertain traffic demand and supply in a stochastic traffic network. First, a link based dynamic network loading model is developed to simulate the traffic flow propagation allowing the change of speed limits. Shockwave propagation is well defined and captured by checking the difference between the queue forming end and the dissipation end. Second, the dynamic speed limit problem is formulated as a Markov Decision Process (MDP) problem and solved by a real time control mechanism. The speed limit controller is modeled as an intelligent agent interacting with the stochastic network environment stochastic network environment to assign time dependent link based speed limits. Based on different metrics, e.g. total network throughput, delay time, vehicular emissions are optimized in the modeling framework, the optimal speed limit scheme is obtained by applying the R-Markov Average Reward Technique (R-MART) based reinforcement learning algorithm. A case study of the Sioux Falls network is constructed to test the performance of the model. Results show that the total travel time and emissions (in terms of CO) are reduced by around 18% and 20% compared with the base case of non-speed limit control.