桥梁超重荷载与限载标准的确定

为了分析公路运营中超重荷载对桥梁的影响，以陕西省府谷-店塔公路上运煤超载车辆为调查对象，根据车辆装载特点和轴型分布特征，将超载车辆分为9种类型，分析了9种车型的超载、超限情况；利用线性回归，得出超载与超限的函数关系。利用等代荷载方法，与公路-Ⅰ级荷载相比较，确定出9种车型的限载系数和限载标准，评价了限载后车辆荷载特性，认为车辆限载后宜使用多轮、多轴运营车型。     

贵州省滑坡灾害危险性分区图编制研究

基于GIS对贵州省区域内的滑坡危险性进行评估.首先,研究将历史地质灾害分布、地形、地层岩性、断裂构造、河流水系和年均降雨量作为相互独立的滑坡诱发因子,并对各因子按照一定标准再次分级,形成滑坡危险性评价指标体系,绘制各因子的分级图层;然后,考虑因子贡献率,以黄金分割法确定6个因子对发生滑坡灾害的权重;最后,在GIS环境下,应用权重线性组合模型建立滑坡危险性分区图.根据该图,研究区域被划分成4个危险等级:灾害密集发育区、灾害中等密集发育区、灾害偶发区、灾害基本不发育区.通过将滑坡危险性分区图与历史滑坡分布图叠加对比,验证分区图的准确性和可靠性.     

Design of robust-stable and quadratic finite-horizon optimal controllers with low trajectory sensitivity for uncertain active suspension systems

This paper presents a design method for designing the robust-stable and quadratic-finite-horizon-optimal controllers of uncertain active suspension systems. The method integrates a robust stabilisability condition, the orthogonal functions approach (OFA) and the hybrid Taguchi-genetic algorithm (HTGA). Using the integrative computational method, a robust-stable and quadratic-finite-horizon-optimal controller with low-trajectory sensitivity can be obtained such that (i) the active suspension system with elemental parametric uncertainties is stabilised and (ii) a quadratic-finite-horizon-integral performance index including a quadratic trajectory sensitivity term for the nominal active suspension system is minimised. The robust stabilisability condition is proposed in terms of linear matrix inequalities (LMIs). Based on the OFA, an algebraic algorithm only involving the algebraic computation is derived for solving the nominal active suspension feedback dynamic equations. By using the OFA and the LMI-based robust stabilisability condition, the dynamic optimisation problem for the robust-stable and quadratic-finite-horizon-optimal controller design of the linear uncertain active suspension system is transformed into a static-constrained-optimisation problem represented by the algebraic equations with constraint of LMI-based robust stabilisability condition; thus greatly simplifies the design problem. Then, for the static-constrained-optimisation problem, the HTGA is employed to find the robust-stable and quadratic-finite-horizon-optimal controllers of the linear uncertain active suspension systems. A design example is given to demonstrate the applicability of the proposed integrative computational approach.     

Lane-harmonised passenger car equivalents for heterogeneous expressway traffic

In order to account for variations in traffic composition during traffic analysis, passenger car equivalent (PCE) factors are used to convert flow rates of various vehicle classes into flow rates in terms of passenger car units (PCUs). Earlier studies have developed various methods to estimate PCE values but only a few of them are based on uninterrupted traffic flow, particularly for flow regimes with heterogeneous traffic where differential (lower) speed limits are imposed on commercial vehicles. This paper proposes a lane-harmonisation approach, which leverages on the high variation in traffic composition across the lanes, to estimate PCE factors for urban expressways. Multiple linear regression is used and the PCE factors obtained for motorcycles, light goods vehicles, and heavy goods vehicles are 0.65, 1.53, and 2.75, respectively. The estimated capacity flow rate after the application of the obtained PCE factors is around 2200 PCUs per hour per lane.     

基于分级多目标决策的干线公交速度引导模型

为解决干线公交速度引导存在多要素关联约束强，全局效果差的问题，本文提出基于分级多目标决策的干线公交速度引导模型。基于公交线路运行特性的全局优化指标优势分析，设计以公交线路综合准点率为主，交叉口停车次数和分段引导速度均衡为辅的线路全局优化目标体系，并考虑多目标间的关联约束和优先控制差异，构建基于拉格朗日乘子法和遗传算法分层组合的干线公交速度引导分级多目标递阶决策模型；最后，通过实际场景测试，验证模型的有效性。测试结果表明：模型能够克服非全局指标优化的局部最优问题，将全线路各班次综合准点率和交叉口停车次数由非全局指标的69.67%和2.37次 ⋅ 班-1 提升到90.53%和1.23次 ⋅ 班-1；并且综合准点率比全局多目标加权方法提升8.65%，能够较好保障综合准点率目标的优先性，有效提升干线公交的通行效率和服务可靠性。     

考虑临时和预约需求的共享泊位动态分配方法

为解决多居住区共享停车场同时存在临时共享停车需求和提前预约共享停车需求的动态泊位分配问题，本文提出将未来几个时段的共享停车供需同时考虑到当前时段泊位分配中的单时段泊位分配方法，并将本时段泊位匹配结果延伸到后续时段，从而提出共享泊位动态分配流程。对临时停车需求，以用户成本最小为目标确立优先泊位匹配的原则；对预约停车需求，以系统收益最大为目标确立在当前时段结束时统一分配泊位的原则。定义4个指标评价模型效果。 选择来源于成都市某共享停车APP的3个居住小区一天的数据，对模型进行实证研究以及灵敏度分析。研究结果表明：临时共享停车需求和提前预约共享停车需求所占比例在0.4~0.6时，泊位分配后总目标表现最好；将未来几个时段的供需同时考虑到当前时段中，泊位分配效果更好，且考虑的未来时段越多，泊位分配后总目标越好；在泊位分配时，为了较好地保证临时停车需求能够优先分配到泊位，往往会造成总目标变差。     

基于线性诱导的公路隧道入口区域交通安全优化研究

为达到驾驶人早发现隧道洞门、早适应环境变化、早决策驾驶行为的目的，通过分析隧道入口区域行车环境下的视距视区与交通安全问题，借鉴常见的线条形视线诱导设施（如反光环、反光条、弹性交通柱等），构建隧道线性诱导系统，并提出基于线性诱导的隧道入口区域改善方法。另外，通过室内模拟试验，采集白天与夜间环境下注视点的位置数据； 将注视区域分为5类，并分析注视点在各区域的视觉转移特性，评价隧道入口区域改善前后的效果。结果表明： 1）隧道线性诱导系统具备形式多样、较大尺寸、可以勾勒轮廓、发光分散等特点，同时可以以低成本提升隧道光环境的安全性。2）隧道入口区域改善前，驾驶人的注视点以较大概率出现在前方近处。3）改善后，驾驶人的注视点以较大的概率出现在前方远处，表明改善方案使得驾驶人的视距充足； 改善后注视点在主要分布区域的注视概率变动比改善前更为缓和，表明驾驶人的视区变化得到缓解。     

Optimization of bus allocation to depots by minimizing dead kilometers

In metropolitan cities, public transportation service plays a vital role in mobility of people, and it has to introduce new routes more frequently due to the fast development of the city in terms of population growth and city size. Whenever there is introduction of new route or increase in frequency of buses, the non‐revenue kilometers covered by the buses increases as depot and route starting/ending points are at different places. This non‐revenue kilometers or dead kilometers depends on the distance between depot and route starting point/ending point. The dead kilometers not only results in revenue loss but also results in an increase in the operating cost because of the extra kilometers covered by buses. Reduction of dead kilometers is necessary for the economic growth of the public transportation system. Therefore, in this study, the attention is focused on minimizing dead kilometers by optimizing allocation of buses to depots depending upon the shortest distance between depot and route starting/ending points. We consider also depot capacity and time period of operation during allocation of buses to ensure parking safety and proper maintenance of buses. Mathematical model is developed considering the aforementioned parameters, which is a mixed integer program, and applied to Bangalore Metropolitan Transport Corporation (BMTC) routes operating presently in order to obtain optimal bus allocation to depots. Database for dead kilometers of depots in BMTC for all the schedules are generated using the Form‐4 (trip sheet) of each schedule to analyze depot‐wise and division‐wise dead kilometers. This study also suggests alternative locations where depots can be located to reduce dead kilometers. Copyright © 2015 John Wiley & Sons, Ltd.     

智能车经济性起步车速规划研究

智能车的车速决策影响燃油经济性。以起步阶段加速工况的燃油经济性为优化目标,建立了瞬态燃油消耗模型,并提出了基于该模型的经济性换挡规律制定方法;根据车辆纵向动力学方程,建立了基于前向欧拉离散方法的车速状态转移方程,以及确定相应的初末约束条件、边界条件;基于动态规划最优性原理,提出了智能车起步过程的经济性车速规划方法,建立了基于速度状态搜索策略;根据Matlab/Simulink和CarSim联合仿真,对比了典型驾驶员速度跟随模式的燃油消耗水平,结果表明,基于动态规划优化后的经济性车速及相应的挡位序列具有良好的节油特性,可为智能车经济驾驶的车速规划及挡位规划提供指导。     

A bi-objective bi-level signal control policy for transport of hazardous materials in urban road networks

A bi-objective bi-level signal control optimization for hazardous material (hazmat) transport is considered to assess trade-offs between travel cost and environment impacts such as public risk exposure. A least maxi-sum risk model with explicit signal delay is presented to determine generalized travel cost for hazmat carriers. Since the bi-level signal control problem is generally a non-convex program, a bundle method using generalized gradients is proposed. A bounding strategy is developed to stabilize solutions of the bi-level program and reduce relative gaps between iterations. Numerical comparisons are made with other risk-averse models. The results indicate that the proposed bi-objective bi-level model becomes even amiable to signal control policy makers since provides flexible solutions whilst is acceptable to carriers since takes account of travel delay at signal-controlled junctions. Moreover, the trade-offs between public risk and generalized travel costs are empirically investigated among different risk models with a variety of weights. As a result, the proposed model consistently exhibits highly considerable advantage on mitigation of public risk whilst incurred less cost loss as compared to other alternatives.