Road Network Reliability Research Articles

Modelling and Forecasting Vehicle Registration System: An Arma Approach

The role of transportation in the promotion of national unity and socio-economic integration in Nigeria cannot be overemphasized. Transport stimulates asense of oneness multi understanding in the cultural diversification of the mostpopulous nation in the sub Sahara of African Continent. it is therefore of interest tostudy using the Autoregressive Moving Average, the transportation system in Nigeriausing Lagos State (being the commercial centre) and also maintains a robust data basethrough the AUTOREG System as a case study by modeling and forecasting theVehicle registration system in terms of types and ownership. The result of theAutoregressive Moving Average (ARMA) approach indicated that there is tendencyfor an increase in the registration of Vehicles in the future. It is therefore suggested that to accommodate an increase in the number of Vehiclesregistration, a robust Vehicle database should be designed across the country forsecurity, research and adequate planning; and Nigerian government at all levels shouldstrive to provide adequate and reliable road network system to meet this emergingdevelopmental activities among others.

Geometric quality enhancement of legacy graphical cadastral datasets through thin plate splines transformation

In some parts of the world, mainly developing countries, analogue graphical cadastral datasets are still being used, despite the fact that they usually contain large and differential positional distortions. This is because not only do they contain useful information, their replacement would involve lengthy legal procedures, huge financial costs and technical challenges as well. This paper presents a novel approach for the conflation of such legacy graphical cadastral datasets to more reliable and accurate topographical datasets based on the matching of linear features via a non-rigid transformation using thin plate spline transformation. The approach consists of three key steps: extraction of road network which is potentially contained in the graphical cadastral maps; matching of corresponding point and linear features between the extracted road network and a more reliable road network dataset; and computation of the non-rigid transformation between the datasets. Applying this reliable and accurate transformation quantification to the original legacy graphical cadastral dataset showed significant improvement in its geometric quality and positional accuracy.

Study on the Road Network Connectivity Reliability of Valley City Based on Complex Network

Based on the research progress in related fields and the distribution characteristics of road networks in valley cities, the complex network model of a city road network is established to study its connectivity reliability. Taking Lanzhou as the example, several parameters of the complex network abstracted from the road network are calculated and the practical meanings of them are described, respectively. On this basis, through computing the global efficiency and the relative size of the largest connecting subgraph under intentional attacks and random attacks, respectively, the curves of the above two parameters varying with the attacking times are drawn. The detailed investigation of connectivity reliability of Lanzhou road network is done by analyzing the curves’ tendency. Finally, we find that the network of a valley city has a poor connection and has a lot of dead ends. Besides, the average length of the roads is very long and the holistic connectivity reliability is at a lower level; these are suitable to the group‐type distribution of valley city’s road network, and the connectivity reliability of the road network is stronger under random attacks than that under intentional attacks.

English

Capacity reliability assessment and application are emerging active area in transportation science. This paper built assessment model of capacity reliability of road network from the perspective of route entropy by referring to relevant concepts and methods applied in water distribution system. Route entropy represents the uncertainty of route selection of macro traffic flow in a road network. The probability space and calculative model of route entropy were introduced as a new method with regard to the field of capacity reliability research in transportation science. This paper further demonstrated a feasible method for applying resultant capacity reliability in logistics network optimization. The decision of how to optimize a logistics network depends upon several criteria that are sometimes conflicting under a set of constraints. This paper analyzed and modeled the conflicting objectives through forming satisfactory function. The proposed approach captured essential requirements of actual logistics network and considered them synthetically into unified dimension for optimization. Improved genetic algorithm was applied to search solutions, and the applicability and validity of the method were further demonstrated by a numerical example. This paper contributed to the development of capacity reliability theory in transportation science. It may bring some inspiration to relevant scientific researchers and engineers. Key words: Road traffic, road network, traffic flow, route choice, entropy, uncertainty, multi-objective, satisfactory optimization, logistics network

Model for Location of Medical Facility and Evaluation of Vulnerability and Accessibility of Road Network

This study proposes a method of evaluating the robustness of a road network against a natural disaster and aims to determine the optimal allocation of medical facilities if road network degradation occurs because of severe natural disasters. Connectivity vulnerability and accessibility are important concepts in evaluating the strength and reliability of road networks. This paper first introduces a new network evaluation measure, the distinct paths–based accessibility index (DPAI), which is based on the concepts of both connectivity vulnerability and accessibility; considers the number of distinct paths between a certain origin–destination pair, free-flow travel time, and the number of opportunities in an area; and develops a solution algorithm. A medical facility location model that optimizes the allocation of a medical facility to each centroid according to the DPAI is then formulated, and the results are applied to a real network. Although the optimal allocation of a medical facility varies according to the minimum DPAI, the robustness of an actual network may be improved by reallocating medical facilities. Moreover, the allocation results depend on the value of the importance placed on the number of distinct paths. These results imply that it is critical to set the parameter on the importance of the number of distinct paths by considering risks and geographical features in the subject area.

Road network vulnerability–evaluation of measures in ranking damages and developments

In this article a practical example on studying vulnerability using the method of the critical scenario and multi-criteria analysis is presented. Giving a simple method to handle reliability related to a certain path, section, link, junction or a whole trip for travelers and operators of urban road networks as users of traffic information systems it would be a huge step forward. The best would be to have one single parameter coming from an engineering calculation or a model, which would mean the same for the user and the engineer, and both of them would be able to use it as it was. Introducing a clear definition of reliability and vulnerability of road networks used by a wide range of applications is of capital importance. This article makes some steps towards achieving this goal.

Research on Unblocked Reliability of Road Network under Different Traffic Demand and Supply Distribution

AbstractUnblocked reliability is a probability index, which reflects the relationship between traffic demand and supply in peak hour at workday. Regarded traffic demand and road capacity as variables conforming normal distribution, the different road network unblocked reliability can be gotten by the random experimentation, and the change rules of road network unblocked reliability and velocity under different supply and demand combination were put foreword. The road network unblocked reliability analyses show that, the change rules of road components, routes, OD, and network are alike; the unblocked criterion is higher, the unblocked reliability is smaller; the traffic demand is lower, the corresponding reliability is higher under the same unblocked criterion and the same demand variation.

Attacker–defender models and road network vulnerability

The reliability of road networks depends directly on their vulnerability to disruptive incidents, ranging in severity from minor disruptions to terrorist attacks. This paper presents a game theoretic approach to the analysis of road network vulnerability. The approach posits predefined disruption, attack or failure scenarios and then considers how to use the road network so as to minimize the maximum expected loss in the event of one of these scenarios coming to fruition. A mixed route strategy is adopted, meaning that the use of the road network is determined by the worst scenario probabilities. This is equivalent to risk-averse route choice. A solution algorithm suitable for use with standard traffic assignment software is presented, thereby enabling the use of electronic road navigation networks. A variant of this algorithm suitable for risk-averse assignment is developed. A numerical example relating to the central London road network is presented. The results highlight points of vulnerability in the road network. Applications of this form of network vulnerability analysis together with improved solution methods are discussed.

A Travel Time Reliability Evaluation Method with a Stochastic Network Equilibrium Model

These days, travel time reliability is shed light on. as an evaluation index of road networks. In fact, travel time or vehicle speed fluctuates from day to day and from time to time. In order to evaluate the performance of road networks more appropriately, it is important to evaluate variation of travel times. In this study, we propose the concept of “Variation Loss Time, ” which is a new evaluation index of road networks using the stochastic network equilibrium model which we proposed before. We evaluated travel time reliability of the Kanazawa road network using the index proposed. The method enables us to grasp problematic part or links on a road network from the standpoint of travel time reliability.

New Methodology to Calculate Unblocked Reliability to Assess Road Network Operation Performance

This paper presents a new methodology to calculate unblocked reliability of a road network. Unblocked reliability analysis is used to assess the operation performance of a road network at peak hour in order to support the decision-making involved in road network planning. A four-level model of road network unblocked reliability (link, path, Origin-destination pair and whole network) is shown to assess the operation performance of each level of the road network. A method of sensitivity analysis is provided to determine the priority of the road section in the planning scheme. However, the most difficult task in unblocked reliability analysis is how to find a route choice pattern, namely, which routes are selected and how proportions of Origin-destination flows are loaded on these used routes between every Origin-destination pair. In order to resolve this problem, a new traffic assignment method is proposed in this paper based on the Frank-Wolf algorithm. This algorithm not only can find the link flows but can also solve the route choice pattern, which satisfy the User Equilibrium criterion. The proposed methodology is applied to solve the goal of traffic demand control and the necessary road capacity when a road network is improved to the expected operation performance. The proposed methodology provides a useful tool to assess the operation performance of a road network at several levels of road capacity and traffic demand, and can be used to evaluate various road network planning and to design a reliable road network system.

USE OF TRAVEL DEMAND SATISFACTION TO ASSESS ROAD NETWORK RELIABILITY

A new concept of network reliability is introduced to assess the performance of the road network. It is referred to as the travel demand satisfaction reliability (DSR). In order to understand this new concept, the attributes to recurrent travel demand are firstly investigated for the analysis of road network reliability. The latent travel demand (LTD) is then distinguished and estimated by elastic travel demand functions. The ratio of the equilibrium travel demand and LTD can be used to ascertain the extent of satisfying and revealing the latent travel demand (DSI), which is affected by both the uncertainty of the network degradation and of the recurrent travel demand. The DSR is defined as the probability that the road network can accommodate a given DSI. The DSR can be extended to include other reliability measures such as travel time reliability under certain conditions. In order to facilitate the presentation of the essential ideas, simple examples are employed for discussion together with mathematical formulation.

Feeding and Fleecing the Native: How the Nyasaland Transport System Distorted a New Food Market, 1890s–1920s*

Failed states in Africa are not a uniquely postcolonial phenomenon: The colonial government in Nyasaland started and ended as a failed state. Although effective in guarding Britain's global interests against her imperial rivals, the Nyasaland government could not be relied upon as a trustworthy ally of any social class within the country. The government failed to provide essential services, particularly roads, with dire consequences for both the peasant economy and European enterprises. Without a reliable road network, transport companies came to depend on the vagaries of the weather and the availability of villagers to carry goods on their heads. Transporters competed with planters and other European enterprises for cheap labour, instituting a costly freight regime that discouraged planters from raising bulky, low-value food crops. Thus, to feed their workers, all European enterprises – farmers, missionaries, traders, transport companies and the government – turned to peasant-grown food. Responding to these demands without the benefit of new agricultural technologies that could have raised productivity, peasants sold the food that their families needed and began to experience new forms of hunger. The food deficits forced the same European planters who assaulted the peasant economy as a system of labour usage to realise the need to preserve it as a system of food supply. Such was the nature of the colonial regime in Nyasaland that stimulating and undermining the peasant option did not form two separate processes, occupying two distinct phases. In Nyasaland, the inefficient transport system, like the estate sector, simultaneously both strengthened and weakened peasant production. The mere feeding of all these [workers] is a problem in itself. (Life and Work in British Central Africa, September 1905) The road question seems to be among the thorny problems which beset this country. (The Central African Times, 6 October 1900)

ON THE ROLE OF ROAD NETWORKS IN REDUCING HUMAN LOSSES AFTER EARTHQUAKES

A road-network reliability analysis for a scenario seismic event is performed for a region of southern Italy characterised by a large number of small to medium municipalities quite close to each other and served by a dense network of roads. Among the many functions of the road network, whose links may fail after an earthquake due to the collapse of the bridges within them, the one selected for the present study is that of allowing rescue operations to be carried out at the sites of collapsed schools. For this to be possible, connection must be maintained between schools that survived, rescue centres and hospitals. Required elements for the study are the fragility curves of the bridges, the schools, the hospitals and the rescue centres. Output of the study is the expected value of the fraction of the total population in the area that is in need of assistance and cannot be hospitalised due to either failure of the network or other vulnerable components.

Monitoring and Predicting Freeway Travel Time Reliability: Using Width and Skew of Day-to-Day Travel Time Distribution

Generally, the day-to-day variability of route travel times on, for example, freeway corridors is considered closely related to the reliability of a road network. The more that travel times on route r are dispersed in a particular time-of-day (TOD) and day-of-week (DOW) period, the more unreliable travel times on route r are conceived to be. In the literature, many different aspects of the day-to-day travel time distribution have been proposed as indicators of reliability. Mean and variance do not provide much insight because those metrics tend to obscure important aspects of the distribution under specific circumstances. It is argued that both skew and width of this distribution are relevant indicators for unreliability; therefore, two reliability metrics are proposed. These metrics are based on three characteristic percentiles: the 10th, 50th, and 90th percentile for a given route and TOD-DOW period. High values of either metric indicate high travel time unreliability. However, the weight of each metric on travel time reliability may be application- or context-specific. The practical value of these particular metrics is that they can be used to construct so-called reliability maps, which not only visualize the unreliability of travel times for a given DOW-TOD period but also help identify DOW-TOD periods in which congestion will likely set in (or dissolve). That means identification of the uncertainty of start, end, and, hence, length of morning and afternoon peak hours. Combined with a long-term travel time prediction model, the metrics can be used to predict travel time (un)reliability. Finally, the metrics may be used in discrete choice models as explanatory variables for driver uncertainty.

State of Practice in Dynamic Traffic Management in the Netherlands

Since 25 years traffic management systems on motorways are deployed. Their goal is to improve the transportation system by making it more effective, more efficient and safer. This paper describes the current state of practice in The Netherlands for measures like signalling, incident management, ramp-metering, peak lanes, etc. Five regional traffic management centres, a countrywide traffic information centre and a countrywide management centre are in charge of the motorway surveillance, in order to guarantee a safe and reliable road network.

Optimal Improvement Scheme for Network Reliability

Performance reliability of road networks has become a more prevailing concern for engineers and planners involved in network design. To improve network reliability the most, engineers and planners may need to decide which links need improvement and at the same time account for the route choice behavior of network users. Using a simple network example, a new reliability version of Braess’s paradox is presented showing that increasing the capacity or decreasing the variability of travel time for some links may actually lead to a less reliable network. A bilevel programming model is proposed through which the reliability paradox can be avoided and an optimal improvement scheme for the existing links may be determined to achieve the most reliable network, subject to a budget constraint. Finally, a numerical example is presented to illustrate the model together with a sensitivity analysis–based algorithm.

Estimating Benefits By Improving The Reliability On Travel Times

The paper presents a probabilistic mode for estimating benefits by improving the reliability on travel times. Normally road network planners only consider benefits of decreasing travel times by constructing new expressways in estimating time related economic benefits. Since there are increasing needs to reduce the risk of arriving late at a destination it has become more important to evaluate the reliability of road networks. The model incorporates the probabilistic characteristics of travel times associated with the designated arrival time.

Assessing Performance Reliability of Road Networks Under Nonrecurrent Congestion

Reliability is becoming an increasingly important attribute of road networks. An approach to assess the performance reliability of road networks under nonrecurrent congestion is suggested. Nonrecurrent congestion can arise anywhere along the roadway; when it does arise, it suddenly reduces the capacity of the roadway and makes the traffic condition unstable. Confronted with such uncertain traffic conditions, commuters are known to exhibit different behaviors, namely, risk aversion, risk neutrality, and risk seeking, which are formulated by the expected disutility approach. Commuters are assumed to choose the path with minimal expected disutility. Consequently, a disutility-related multiclass user equilibrium might be achieved when the expected travel disutility between each origin-destination pair can be determined separately and uniquely. Because this disutility implies dissatisfaction or disliking with levels of variations of travel times perceived by commuters, it offers a suitable measure of network reliability for network design. The disutilityrelated multiclass user equilibrium is formulated as a nonlinear complementarity problem, which is a nonadditive path cost problem and can be solved by recently proposed path-based algorithms. Numerical examples are provided to illustrate the application of the proposed approach.

Basic concepts and future directions of road network reliability analysis

AbstractThe stability of road networks has become an increasingly important issue in recent times, since the value of time has increased considerably and unexpected delay can results in substantial loss to road users. Road network reliability has now become an important performance measure for evaluating road networks, especially when considering changes in OD traffic demand and link flow capacity over time.This paper outlines the basic concepts, remaining problems and future directions of road network reliability analysis. There are two common definitions of road network reliability, namely, connectivity reliability and travel time reliability. As well, reliability analysis is generally undertaken in both normal and abnormal situations. In order to analyse the reliability of a road network, the reliability of the links within the network must be first determined. A method for estimating the reliability of links within road networks is also suggested in this paper.

An Evaluation Model of Road Network Reliability with Degraded Links by Natural Disasters

An Evaluation Model of Road Network Reliability with Degraded Links by Natural Disasters