Combining driver response with cyclical queue optimisation over selected corridors

A case study located in Auckland, New Zealand, was used to quantify the magnitude of savings that may result if the SCATS adaptive traffic control system contains an explicitly combined queue estimation and offset adjustment on a cycle‐by‐cycle basis. A validated SATURN traffic model was used to evaluate five scenarios that represent the short‐run and long‐run efficiency gains resulting from progressive signal adaption with an objective of queue minimisation on the main corridors. Optimisation was applied both area‐wide, and on selected arterial corridors, using a combined split/offset optimisation routine with responsive driver behaviour to achieve a network‐wide and corridor‐specific efficiency gain. The modelling heuristic evaluates the efficiency of both the Equisat and P₀ optimisation policies that would mimic a more progressive adaption of signals under SCATS. Results for the long‐run area‐wide optimisation can produce network‐wide travel‐time savings in the order of 20% and a reduction in transient queues of 28% if only selected corridors are optimised, with a 5% reduction in journey time over an average 8‐min journey. Copyright © 2016 John Wiley & Sons, Ltd.     

Transit investment and economic development

This paper describes the development of approaches to analysing the links between investment in transit and economic development. It indicates the need to bring together disparate approaches from urban economics and transportation economics to get a full understanding and uses recent results on agglomeration economies to present a more rigorous model of the wider economic benefits of transit investment. Although the evidence increasingly points towards identifiable benefits over and above those captured in conventional transport cost-benefit analysis, the chapter counsels against the assumption of simple rules.     

A statistical investigation of time-variant hull girder strength of aging ships and coating life

Risk- and reliability-based approaches are increasingly being applied in assisting inspection and maintenance planning. One of the keys to such approaches is properly predicting the hull girder strength (HG) of gradually degradated hull structures. The development has been limited by the lack of data on aging ships—validation of the developed methods has not been possible. To fill the gap of knowledge on hull strength of ships in service, this paper presents a database of as-gauged hull structures and a statistical study of the time-variant HG of tankers. The expanded data set was collected from 2195 as-gauged girth belts (transverse sections) of 211 single-hull tankers that were 12–32 years old. It was intended to (1) provide actual data on hull girder section modulus (HGSM) of tankers, (2) investigate the general trends of the change in the HG over ships’ service life, and (3) propose formulations for presenting time-variant HGSM and coating life.

The data set demonstrated a high variation of HGSM that changed over time. The mean value and standard deviation of HGSM loss were derived as functions of time. The probability density function (pdf) of coating life was also derived. Comparisons were made between previous studies on HG and the current data set. It was found that almost all previous studies showed much greater HG loss than what this database revealed. The refinement of existing calculations appears to be needed. The data set and statistical study were expected to form the basis for validating formulations of HG that are key components in risk- and reliability-based approaches.     

A robust,data-driven methodology for real-world driving cycle development

This paper develops a robust, data-driven Markov Chain method to capture real-world behaviour in a driving cycle without deconstructing the raw velocity–time sequence. The accuracy of the driving cycles developed using this method was assessed on nine metrics as a function of the number of velocity states, driving cycle length and number of Markov repetitions. The road grade was introduced using vehicle specific power and a velocity penalty. The method was demonstrated on a corpus of 1180 km from a trial of electric scooters. The accuracies of the candidate driving cycles depended most strongly on the number of Markov repetitions. The best driving cycle used 135 velocity modes, was 500 s and captured the corpus behaviour to within 5% after 1,000,000 Markov repetitions. In general, the best driving cycle reproduced the corpus behaviour better when road grade was included.     

Power plant siting on Wisconsin's coasts: A case study of a displaceable use

Abstract

The issue of whether power plants should be located on Wisconsin's Lake Michigan shore or inland is addressed in this article. It is quite likely that sites for several large power plants will be needed before the year 2000. Available evidence on the comparative costs of condenser cooling indicates that there may or may not be substantial economies from locating these plants at lakeshore sites depending on site characteristics, fuel costs, and other variables. Environmental impacts of coastal and inland siting are surveyed and also appear to be highly site‐specific. Important issues arise with respect to the intense competition for coastal land and the aquatic impacts at both coastal and inland sites. A third alternative, that of utilizing sites that are in the coastal zone but set back from the water's edge, has some promising aspects, but data on costs are scarce and inconclusive. Conclusions center on the importance of not ruling out either coastal or inland locations in future efforts to identify suitable power plant sites, the need to review current water‐quality measures, and the need for further research on institutions to facilitate sound siting decisions.     

Engaging paratransit on public transport reform initiatives in South Africa: A critique of policy and an investigation of appropriate engagement approaches

A number of South African cities are planning integrated public transport networks that rely on the introduction of Bus Rapid Transit (BRT), in line with similar trends to expand or upgrade public transport services in emerging and industrialised urban transport markets around the globe. In addition, BRT in South Africa is being used as a mechanism to drive reform in the dominant yet highly fragmented paratransit sector, inspired by similar processes particularly in Latin American cities such as Bogotá, Mexico City, and Santiago de Chile. Thousands of paratransit operators would have to formalise their businesses, or merge into new or existing operator entities in order to participate in the new systems. There is, however, an absence of accessible business plans and regulatory regime proposals around which paratransit can be engaged to convince it to alter its current modus operandi. A large number of national, regional and local paratransit groupings have furthermore indicated their resistance to the planned networks on the grounds of insufficient consultation, an unclear future role in the system and employee redundancies. Should this deadlock not be resolved, it seems unlikely that the planned networks will be realised in the proposed timeframes, if indeed at all. This paper investigates the South African passenger transport policy framework that has contributed to the current deadlock, and explores appropriate approaches to engaging paratransit operators on a system of contracting, competition and ownership that recognises the sector’s aspirations and fragmented nature, yet contributes towards improved passenger transport services. It is the authors’ view that paratransit reform is a highly context-specific process, even at the sub-city level, and that this could prevent transferring paratransit regulatory and integration approaches across countries, and even cities in the same country, without adaptation to local conditions.     

Real-time traffic estimation using data expansion

This paper presents a method for estimating missing real-time traffic volumes on a road network using both historical and real-time traffic data. The method was developed to address urban transportation networks where a non-negligible subset of the network links do not have real-time link volumes, and where that data is needed to populate other real-time traffic analytics. Computation is split between an offline calibration and a real-time estimation phase. The offline phase determines link-to-link splitting probabilities for traffic flow propagation that are subsequently used in real-time estimation. The real-time procedure uses current traffic data and is efficient enough to scale to full city-wide deployments. Simulation results on a medium-sized test network demonstrate the accuracy of the method and its robustness to missing data and variability in the data that is available. For traffic demands with a coefficient of variation as high as 40%, and a real-time feed in which as much as 60% of links lack data, we find the percentage root mean square error of link volume estimates ranges from 3.9% to 18.6%. We observe that the use of real-time data can reduce this error by as much as 20%.     

充满挑战的中国汽车导航业

中国消费者导航使用频率高根据Strategy Analytics对北美、欧洲和中国市场进行的调查,中国的驾车者对导航仪的使用最为频繁.2011年11月StrategyAnalytics分别在西欧和美国各抽取1200名、在中国抽取2000名用户,就消费者对嵌入式导航、便携式导航及手机导航的兴趣、习惯和满意度等问题进行了调研.调研结果显示,嵌入式导航的使用频率比另两类导航更高.     

Contracting for public transportation service

There is increasing interest in contracting to private industry for the provision of public transportation. The trend has accelerated since the mid 1970's spreading from local to regional transit authorities as the need for cost savings arise. Promising major savings without major service reductions, the merits of the strategy are now being evaluated at various levels. This paper focusses on the extent and magnitude of service contracting, the reasons why some agencies adopt the strategy, the nature and capability of the contractors and the actual performance of the arrangements.