A continuous-flow-intersection-lite design and traffic control for oversaturated bottleneck intersections

Oversaturation has become a severe problem for urban intersections, especially the bottleneck intersections that cause queue spillover and network gridlock. Further improvement of oversaturated arterial traffic using traditional mitigation strategies, which aim to improve intersection capacity by merely adjusting signal control parameters, becomes challenging since exiting strategies may (or already) have reached their “theoretical” limits of optimum. Under such circumstance, several novel unconventional intersection designs, including the well-recognized continuous flow intersection (CFI) design, are originated to improve the capacity at bottleneck intersections. However, the requirement of installing extra sub-intersections in a CFI design would increase vehicular stops and, more critically, is unacceptable in tight urban areas with closed spaced intersections. To address these issues, this research proposes a simplified continuous flow intersection (called CFI-Lite) design that is ideal for arterials with short links. It benefits from the CFI concept to enable simultaneous move of left-turn and through traffic at bottleneck intersections, but does not need installation of sub-intersections. Instead, the upstream intersection is utilized to allocate left-turn traffic to the displaced left-turn lane. It is found that the CFI-Lite design performs superiorly to the conventional design and regular CFI design in terms of bottleneck capacity. Pareto capacity improvement for every traffic stream in an arterial system can be achieved under effortless conditions. Case study using data collected at Foothill Blvd in Los Angeles, CA, shows that the new design is beneficial in more than 90% of the 408 studied cycles. The testing also shows that the average improvements of green bandwidths for the synchronized phases are significant.     

The Integrated Model on Mobile Payment Acceptance (IMMPA): An empirical application to public transport

This study examines the users’ acceptance and usage of mobile payments, focusing on the mobile ticketing technologies applied in a public transport context. We investigate the main predictors of the intention to use mobile ticketing and the relation between those predictors, considering the prominent literature on users’ technology acceptance background and extending the knowledge through an innovative contribution. The main models of reference in this study are the Technology Acceptance Model (TAM), the Diffusion of Innovation Model (DOI) and the Unified Theory of Acceptance and Use of Technology (UTAUT) model. The new model that we proposed is called the Integrated Model on Mobile Payment Acceptance (IMMPA), and it was designed specifically for mobile payments in the public transport, on the basis of the models previously mentioned. It was developed by mixing the variables of the existing models and adding new ones tailored to the mobile payment/ticketing framework. The theoretical framework was tested using the Structural Equation Models. The results show that the intention to use a technology is affected by the Usefulness, Ease of use and the Security of that technology. Moreover, the Usefulness is simultaneously influenced by the Ease of use, the Compatibility with users’ values and needs and their Attitude towards mobile services. Furthermore, the model confirms the direct relation between the intention to use a technology and its actual usage. The new predictor, that is the Attitude towards mobile services, includes those requirements that every mobile ticketing payment must address in this context: complete information, further information about time and delay, speed of use, intuitive interface, and path customisation. Another new construct detected is the Security, in reference to mobile payment. Because it could represent an obstacle to mobile ticketing distribution, it must be considered by market operators. The originality of the paper addresses the realisation of a new model, the IMMPA, which was specifically designed for mobile payment in the public transport.     

边坡锚索锚杆防护位置选取浅析

文章以某高速公路边坡锚索与锚杆联合防护设计为例,对不同锚索位置的边坡等效塑性应变、坡面最大水平位移及相应的安全系数进行了模拟计算分析。结果表明,锚索防护位置处于开挖坡面的最上部最合理,可用最节约的成本达到相对合理的设计结果。     

Multi-modal traffic signal control with priority,signal actuation and coordination

Both coordinated-actuated signal control systems and signal priority control systems have been widely deployed for the last few decades. However, these two control systems are often conflicting with each due to different control objectives. This paper aims to address the conflicting issues between actuated-coordination and multi-modal priority control. Enabled by vehicle-to-infrastructure (v2i) communication in Connected Vehicle Systems, priority eligible vehicles, such as emergency vehicles, transit buses, commercial trucks, and pedestrians are able to send request for priority messages to a traffic signal controller when approaching a signalized intersection. It is likely that multiple vehicles and pedestrians will send requests such that there may be multiple active requests at the same time. A request-based mixed-integer linear program (MILP) is formulated that explicitly accommodate multiple priority requests from different modes of vehicles and pedestrians while simultaneously considering coordination and vehicle actuation. Signal coordination is achieved by integrating virtual coordination requests for priority in the formulation. A penalty is added to the objective function when the signal coordination is not fulfilled. This “soft” signal coordination allows the signal plan to adjust itself to serve multiple priority requests that may be from different modes. The priority-optimal signal timing is responsive to real-time actuations of non-priority demand by allowing phases to extend and gap out using traditional vehicle actuation logic. The proposed control method is compared with state-of-practice transit signal priority (TSP) both under the optimized signal timing plans using microscopic traffic simulation. The simulation experiments show that the proposed control model is able to reduce average bus delay, average pedestrian delay, and average passenger car delay, especially for highly congested condition with a high frequency of transit vehicle priority requests.     

Cycleways and footpaths: What separation is needed for equivalent air pollution dose between travel modes?

Cycling and walking are being promoted in many urban areas as alternatives to motorised transport for health, environmental, and financial reasons. The reduced congestion and resulting decrease in the overall amount of pollution reduced can be expected to result in health benefits for the community. However, active commuters, due to their increased respiration rates and often increased travel times can expect to receive larger doses of air pollution compared with those using motorised forms of transport. However, given the large dropoff in concentrations away from a road, it can be expected that significant reductions can be achieved even with relatively small increases in separation between the path of cyclists/pedestrians and motor vehicles.This study presents a simple methodology for calculating the separation needed for cyclists and pedestrians to experience the same air pollution dose as car commuters. An example is given based on carbon monoxide (CO) data collected in a field campaign consisting of a car driver, a cyclist and a pedestrian travelling on a 2600 metre loop of road in Auckland. For this case study, the estimated distance from the centreline needed for cyclists and pedestrians to receive an equivalent dose of CO as motorists was found to range from 5.8 to 14.2 m depending on the commuting mode and the dispersion state of the atmosphere at the site. This was equal to a CO concentration reduction of 0.1–0.14 ppm per metre. Recommendations on facility modifications and route selections have been made to make active mode commuting safer.     

Multi-stage stochastic program to optimize signal timings under coordinated adaptive control

In the wake of traffic congestion at intersections, it is imperative to shorten delays in corridors with stochastic arrivals. Coordinated adaptive control can adjust green time flexibly to deal with a stochastic demand, while maintaining a minimum through-band for coordinated intersections. In this paper, a multi-stage stochastic program based on phase clearance reliability (PCR) is proposed to optimize base timing plans and green split adjustments of coordinated intersections under adaptive control. The objective is to minimize the expected intersection delay and overflow of the coordinated approach. The overflow or oversaturated effect is explicitly addressed in the delay calculation, which greatly increases the modeling complexity due to the interaction of overflow delays across cycles. The notion of PCR separates the otherwise related green time settings of consecutive cycles into a number of stages, in which the base timing plan and actual timing plan in different cycles are handled sequentially. We then develop a PCR based solution algorithm to solve the problem, and apply the model and the solution algorithm to actual intersections in Shanghai to investigate its performance as compared with Allsop’s method and Webster’s method. Preliminary results show the PCR-based method can significantly shorten delays and almost eliminates overflow for the coordinated approaches, with acceptable delay increases of the non-coordinated approaches. A comparison between the proposed coordinated adaptive logic and a coordinated actuated logic is also conducted in the case study to show the advantages and disadvantages.     

一种基于移动台位置的动态定位算法

根据检测电波到达时间（TOA）的定位法提出了一种基于移动台位置的动态定位算法。该算法利用蜂窝网络系统中多个基站检测到的移动台电波TOA信息对移动台进行定位估计,参与定位估计的基站数目及其定位算法中相应的权值随移动台与服务基站的距离自动动态改变。计算机模拟结果表明,该算法在3种典型移动通信信道环境中都能得到较好的定位效果。     

辽宁高速公路数据中心云平台建设

针对辽宁高速中心架构进行分析,根据云计算技术的发展,对辽宁高速的IT基础架构进行重新设计,提高数据中心的智能化水平,满足对数据中心的精细化管理的需求;为新业务系统的上线提供快速、高效的支持,并提高后期系统的可维护性;解决目前系统瓶颈,并满足未来可预见的扩容需要;对于辽宁高速新的数据中心的设计要立足于国家的云计算战略,使得辽宁高速的数据中心实现云计算实现的IT即服务,成为辽宁高速业务增长的助推器。     

筑路机械电器系统瞬间过电压保护

以筑路机械电器系统瞬间过电压的保护方式为研究对象，对瞬间过电压的状态进行分析，并借鉴国外典型保护性理论，推荐适合国情的实用性电路，以期对筑路机械电器系统过电压保护有参考价值。