Control Concepts for Facilitating Motorway On-ramp Merging Using Intelligent Vehicles

Abstract

Congestion at motorway junctions is a traffic phenomenon that degrades operation of infrastructure and can lead to breakdown of traffic flow and associated reduction in capacity. Advanced communication technologies open new possibilities to prevent or at least delay this phenomenon, and innovative active traffic management systems have been developed in the recent years for better control of motorway traffic. This paper presents a review of control strategies for facilitating motorway on-ramp merging using intelligent vehicles. First, the concepts of the control algorithms are reviewed chronologically divided into three types of intelligent vehicle: completely automated, equipped with cooperative adaptive cruise control and equipped with on-board display. Then, a common structure is identified, and the algorithms are presented based on their characteristics in order to identify similarities, dissimilarities, trends and possible future research directions. Finally, using a similar approach, a review of the methods used to evaluate these control strategies identifies important aspects that should be considered by further research on this topic.     

Allocating Revenue Risk in Transport Infrastructure Public Private Partnership Projects: How it Matters

Abstract

Transport infrastructure public private partnership (PPP) projects are very diverse and complex in nature not only because of their mode-specific intricacies but also because of their inherent economic characteristics that relate to the scope of involvement of the private sector in the project, the large sunk costs incurred, and ultimately, the competition to which these projects are exposed. The allocation of revenue risk is of paramount importance for the successful implementation of such projects and a sub-optimal allocation may lead to project structuring that is unnecessarily expensive and vulnerable to failure. At the same time, the revenue risk depends critically on the remuneration model used (user-based versus budget-based) and may, in turn, take the form of demand risk, counterparty risk or combinations of the two. This review explores the issues related to revenue risk allocation for transport infrastructure PPP projects. Overarching principles for the allocation of revenue risk that transcend mode-specificity are identified and compared to case studies generated in the context of the COST Action TU1001. The results show that theory and practice are divergent, leading to sub-optimal structuring and exposing projects to potential failure.     

Renegotiating PPP Contracts: Reinforcing the ‘P' in Partnership

Abstract

The issue of renegotiation is becoming increasingly important as a tool to address uncertainty of public private partnership (PPP) projects and as a mechanism to restore its economic and financial equilibrium. This paper aims to understand how and why renegotiations occur in long-lasting PPP projects and what are the pros and cons of the renegotiation. We depart from a literature review on contract incompleteness and on the determinant factors for the renegotiation of infrastructure concessions. To illustrate the discussion, the case studies of nine European PPP projects are analysed by examining the specific exogenous and endogenous determinant factors that conduce to renegotiating contracts. The implications of contractual renegotiations are explained and summarized through a comparison of our case studies with literature. Although renegotiation, per se, is not a solution for the successful implementation of PPP projects, our findings reinforce the idea of contractual flexibility as a tool that allows adapting to uncertainty. Moreover, effective communication mechanisms allow a better response to unforeseen events, reinforcing the partners’ commitment to deliver a win–win project.     

Measuring Success of PPP Transport Projects: A Cross-Case Analysis of Toll Roads

Abstract

The aim of this paper is to measure ‘overall’ success of a public private partnership (PPP) transport projects using four case studies. All four case studies are PPP toll roads from four different EU countries (UK, Spain, Portugal and Greece). The case studies have been analysed using a manual Qualitative Comparative Analysis approach. According to the paper, three different perspectives have been used to measure the success of a project, that is, project management perspective, stakeholder perspective and contract management perspective. The ‘overall’ success has then been deduced by bringing these three perspectives together as a holistic approach. The findings are presented in the form of a matrix and the final outcome of the paper shows a simple methodological approach that can be used to measure success of a PPP transport project. Since the study takes more of a qualitative approach, researcher bias and perceptions have a major role to play in the final outcome. However, to reduce ‘biasness’, quantitative measures have also been used to quantify the Key Performance Indicators and performance measures in the case studies. It is hoped that the study makes a valid contribution to the areas of transport PPPs and performance measurement.     

Developing Transport Infrastructure in Sub-Saharan Africa through Public–Private Partnerships: Policy Practice and Implications

In contemporary times, Public–Private Partnership (PPP) in transport infrastructure has gained considerable attention in developing regions following its success in the developed countries. However, Sub-Saharan Africa (SSA) is among the developing regions with few transport PPP projects and among the regions with high number of failed projects. Meanwhile the region's transport infrastructure need far exceeds it current provision. This paper therefore aims to examine the project experiences (success and failure factors) of three highly profiled transport PPP projects, namely the Lekki toll road concession project (Nigeria), N4 toll road (South Africa/Mozambique) and Port of Maputo (Mozambique) in order to develop policy measures for effective future implementation. The experiences of the three projects show that transport PPP policy is indeed feasible in SSA. However, to realise its full applicability, proper policy actions and measures must be carefully observed and these include effective and efficient stakeholder management, transparent and competitive tendering process, high participation of local investors, stable macro-economic conditions and strong government commitment and regulatory framework. The projects experiences and policy actions developed are impactful in accelerating transport infrastructure development through PPP approach in SSA. Hence it is hoped that policy-makers and practitioners would be informed on the key strategies to employ in implementing future projects.     

Optimisation of dynamic motorway traffic via a parsimonious and decentralised approach

This paper presents an optimisation framework for motorway management via ramp metering and variable speed limit. We start with presenting a centralised global optimal control problem aiming to minimise the total travel delay in a motorway system. Given the centralised global optimal control solutions, we propose a set of decentralised ramp metering and speed control strategies which operate on a novel parsimonious dynamic platform without needing an underlying traffic model. The control strategies are applied to a case on UK M25 motorway. The results show that the proposed set of decentralised control is able to deliver a performance that is close to the global optimal ones with significantly less computational and implementation effort. This study provides new insights to motorway management.     

Remuneration models and revenue risk mitigation in road public–private partnership projects – a case study from Serbia

As a consequence of renewed interest in attracting private financing for infrastructure investments, public–private partnership (PPP) arrangements are mostly seen as a suitable mechanism for ensuring sound and quicker delivery of transport infrastructure projects. However, a general concern is that expectations of mobilizing private-sector funds have been overestimated in a number of cases. The purpose of this paper is to contribute to the risk analysis of transport PPP projects with substantial exogenous demand risk which could serve as a rationale for choosing the appropriate PPP model. The objective of this paper is to construct an analytical cash flow-based project model to facilitate the choice of the remuneration mechanism suitable for both private investors and public sector. The model provides an indication whether the project should be implemented as a ‘users pay’, a hybrid or an ‘annuity’ PPP model. The proposed methodology is illustrated using a case study from Serbia.     

Cost overruns in transportation infrastructure projects: Sowing the seeds for a probabilistic theory of causation

Understanding the cause of cost overruns in transportation infrastructure projects has been a topic that has received considerable attention from academics and the popular press. Despite studies providing the essential building blocks and frameworks for cost overrun mitigation and containment, the problem still remains a pervasive issue for Governments worldwide. The interdependency that exists between ‘causes’ that lead to cost overruns materialising have largely been ignored when considering the likelihood and impact of their occurrence. The vast majority of the cost overrun literature has tended to adopt a deterministic approach in examining the occurrence of the phenomenon; in this paper a shift towards the adoption of pluralistic probabilistic approach to cost overrun causation is proposed. The establishment of probabilistic theory incorporates the ability to consider the interdependencies of causes so to provide Governments with a holistic understanding of the uncertainties and risks that may derail the delivery and increase the cost of transportation infrastructure projects. This will further assist in the design of effective mitigation and containment strategies that will ensure future transportation infrastructure projects meet their expected costs as well as the need of taxpayers.     

Transaction Costs in Transport Public–Private Partnerships: Comparing Procurement Procedures

Abstract

In recent years, concern has grown over good practices in the procurement process in public–private partnerships (PPPs). The consensus view is that PPPs are prone to higher transaction costs than traditional public provision. In this paper, we contrast the hypothesis that transaction costs in transport PPPs depend, to a large extent, on the procurement mechanism used in each case, comparing the Negotiated and the Open procedures. Given that PPPs may offer considerable benefits and significant savings over the entire life cycle of the project, it is essential for PPPs to minimize those costs that undermine efficiency gains and that deter private involvement. The quantitative analysis undertaken in this paper highlights that there is room for important savings in the tendering of PPP transport infrastructure projects, using an Open procedure.     

Agricultural vehicles and sustainable safe road traffic: solving conflicts on arterial highways

Addressing the issues of traffic safety in rural areas presents a constant challenge. The mix of light and heavy vehicles and the considerable differences in speed among these traffic participants result in high risks and delays for the faster vehicles. Agricultural vehicles (AVs) in particular have such an impact on traffic, especially when using arterial highways. This paper reviews the problems of safety and delays that AVs cause on arterial highways, and the appropriate mitigation. The concept of 'sustainable safety' in The Netherlands focuses on these problems, because of the proposed construction of parallel roads alongside all arterial highways. However, Dutch accident statistics cannot justify the high costs for the construction of parallel roads alongside 7000 km of arterial highways. Delays experienced by fast traffic are another reason for separating AVs from other road users with parallel roads. Alternative measures alongside the arterial highway, such as passing bays, restricting AVs to travelling at off-peak only and improving the conspicuity of the AVs, may be more cost-effective ways of reducing delays and/or improving traffic safety on arterial highways. Another solution may be to eliminate the need for AVs to use the arterial highway by altering their routes. For this purpose, land reallocation projects (as practised in Holland) can provide a useful tool.     

地铁建设工程的风险管理应用研究

地铁建设工程作为一项大型工程项目,往往存在着大量的不确定风险因素,因而风险管理在地铁工程中变得越来越重要.文章通过对国内外地铁工程事故经验的探讨,提出了地铁建设工程中风险管理的框架,包括风险辨识、分析和评估、应对以及风险防范措施等,以预防和减轻地铁工程风险,达到降低风险等级的目的.     

Impact of Everyday Weather on Individual Daily Travel Behaviours in Perspective: A Literature Review

Despite the hundreds of billions of dollars being spent on infrastructure development -- from roads, rail and airports to energy extraction and power networks to the Internet -- surprisingly little reliable knowledge exists about the performance of these investments in terms of actual costs, benefits and risks. This paper presents results from the first statistically significant study of cost performance in transport infrastructure projects. The sample used is the largest of its kind, covering 258 projects in 20 nations worth approximately US$90 billion (constant 1995 prices). The paper shows with overwhelming statistical significance that in terms of costs transport infrastructure projects do not perform as promised. The conclusion is tested for different project types, different geographical regions and different historical periods. Substantial cost escalation is the rule rather than the exception. For rail, average cost escalation is 45% (SD=38), for fixed links (tunnels and bridges) it is 34% (62) and for roads 20% (30). Cost escalation appears a global phenomenon, existing across 20 nations on five continents. Cost estimates have not improved and cost escalation not decreased over the past 70 years. Cost estimates used in decision-making for transport infrastructure development are highly, systematically and significantly misleading. Large cost escalations combined with large standard deviations translate into large financial risks. However, such risks are typically ignored or underplayed in decision-making, to the detriment of social and economic welfare.     

Fatigue in transport: a review of exposure,risks, checks and controls*

Human fatigue continues to threaten safe transport. There are claims that employers of operators should do more to mitigate the risks, and several regulators are promoting fatigue-risk management in the context of safety management systems (SMS). The current paper reviews fatigue-related risk and exposure factors and control measures for operators of land- and sea-based transport forms. Our review identifies 13 types of measures for the monitoring or control of fatigue risks: optimal staffing; optimal schedule design; optimisation of breaks/naps; monitoring of actual hours worked; optimisation of work content; monitoring and feedback of actual sleep; health screening and treatment; promotion of recovery from work; fitness-for-duty testing; monitoring of fatigue symptoms while operating; control of fatigue while operating; performance monitoring and assistance; and fatigue-proofing. We also identify two systemic measures needed to anchor risk mitigation in SMS: organisational learning and training/other. By structuring monitoring and control measures along Dawson and McCulloch’s [Managing fatigue: It’s about sleep. Sleep Medicine Reviews, 9(5), 365–380] fatigue-risk trajectory, a framework is obtained that acts as a guide for fatigue-risk management by transport employers. To inform transport managers further, evaluations are needed of the effectiveness of individual control measures as well as whole fatigue-risk management interventions.     

关于降低和规避大项目管理风险的探索

文章针对当前施工企业大项目管理现状,分析了大项目管理中存在的主要风险,提出了降低和规避大项目管理风险的措施及建议。     

Traffic flooding the low countries: How the Dutch cope with motorway congestion

Motorway congestion is a common characteristic of the larger conurbations all over the world. Using the example of the Randstad region in The Netherlands, the causes and conditions for the growing congestion on main roads are presented and explained. From an international comparison it appears that the Randstad region is characterized by a relatively high density and high-access quality of its motorway network, giving rise to an extremely high level of usage. The Dutch policy of coping with the consequent congestion problems at the network design level is outlined, followed by a presentation of the dynamic traffic management approaches to these problems. Special attention is given to the so-called target group policy that aims at prioritizing specific user groups such as freight traffic and trucks. Finally, attention is given to the Dutch attempts to introduce congestion pricing as a means of tackling congestion.     

PPP模式下高速公路项目施工期环境保护与水土保持管理探讨

PPP工程总承包是国家现阶段正在推行的建设项目组织模式,以专业投资公司联合专业施工单位及设计院为主进行PPP工程总承包是新兴的一种探索模式。在国内环水保形势日益严峻的情况下,如何做好PPP模式下高速公路项目环水保管理工作成为新的挑战。通过张扁高速公路PPP模式的应用,从公路工程建设过程中产生环、水保问题的原因与危害着手,分别从建设单位、监理单位、施工方简单阐述了各自的环、水保管理责任以及具体的控制措施;建设单位作为环、水保工作的总组织者、总协调者的作用不容忽视,在建设单位统一布局与领导下,通过有效管理可将环、水保问题控制在可控范围,使我国的高速公路建设向着生态公路的方向发展。     

A multiobjective chance constrained programming model for supplier selection under uncertainty

Risk management is an inherent part of supplier selection. While companies are enjoying the benefits of outsourcing, risks brought by this practice should be taken into account in the process of decision making. This paper presents a multiobjective stochastic sequential supplier allocation model to help in supplier selection under uncertainty. Demand for products, capacities at suppliers as well as transportation and other variable costs are the main sources of uncertainty and are modeled using probability distributions. Disruptions are exogenous events and the model provides proactive mitigation strategies against disruptions by assigning backup suppliers who can be used in case of a default at a primary supplier. When there is no disruption, the model’s solution is an optimal supplier order assignment, considering operational risks.     

Mitigating environmental impacts in advance: Evidence of cost and time savings for transportation projects

The traditional model for mitigating a transportation project’s environmental impacts typically operates project-by-project and delivers the mitigation just-in-time. In contrast, the newer practice of advance mitigation comprehensively assesses and mitigates impacts from one or multiple transportation projects before or during project planning, sometimes long before project construction begins. The practice has gained adherents for its potential to improve ecological outcomes, by better aligning mitigation and conservation goals. Advance mitigation also stands to reduce mitigation costs, an important secondary benefit for transportation agencies with constrained resources. Evidence of cost savings, however, has been piecemeal and anecdotal. This paper advances knowledge of advance mitigation’s financial impacts in two ways. First, it critically assesses the evidence about cost savings realized through advance mitigation, both through avoided up-front costs and reduced project delay. Second, it directly estimates the project time savings that might accrue with advance mitigation of state highway projects in California. Overall, the balance of evidence is encouraging for transportation agencies that would introduce the practice, and general agreement exists on its financial benefits. Considering project delays related only to the environmental process, we estimate advance mitigation could reduce delivery times by 1.3–5.0 months per project. Still, we also identify factors limiting comprehensive analysis. Transportation agencies adopting advance mitigation practices into their operations could use a pilot approach that includes rigorous environmental and mitigation cost accounting; such pilots would build needed empirical evidence of advance mitigation’s financial and ecological outcomes.     

How Do Governments Support the Development of Public Private Partnerships? Measuring and Comparing PPP Governmental Support in 20 European Countries

Abstract

Taking an institutional perspective, in this article we develop an index of the governmental support for public private partnership (PPP) — a ‘PPP Governmental Support Index’ (GSI) — which aims to measure the extent to which national governments provide an institutional framework that is either conducive or preventive for the introduction and diffusion of PPPs within transport infrastructure and other sectors. First, based on a substantive review of the literature, we define the elements of the PPP GSI, including the policy and political commitment regarding PPPs, the legal and regulatory framework, and the presence/absence of dedicated PPP-supporting arrangements. Second, we calculate the PPP GSI for 20 European countries, cluster them and compare similarities and differences in national governmental support of infrastructure PPPs. Third, we explore the potential link between national institutional index scores and infrastructure PPP activity in the 20 countries. Lastly, we discuss the potential and usefulness of the presented PPP GSI, as well as methodological limitations, and elaborate on how this index might be utilised to strengthen future comparative research on PPP in transport and other sectors.