"OpenStreetMap kreira i pruža slobodne geografske podatke, kao sto su karte gradova i naselja svakome tko ih želi. Projekt je nastao iz razloga sto vecina karata za koje mislite da su slobodne za koristenje, ustvari imaju pravna ili tehnicka ogranicenja za njihovu uporabu, sto sprijecava ljude da ih koriste na kreativne, produktivne te neocekivane nacine."

Open Street Map

It is well known that, for major infrastructure networks such as electricity, gas, railway, road, and urban water networks, disruptions at one point have a knock on effect throughout the network. There is an impressive amount of individual research projects examining the vulnerability of critical infrastructure network. However, there is little understanding of the totality of the contribution made by these projects and their interrelationships. This makes their review a difficult process for both new and existing researchers in the field. To address this issue, a two-step literature review process is used, to provide an overview of the vulnerability of the transportation network in terms of four main themes - research objective, transportation mode, disruption scenario and vulnerability indicator –involving the analysis of related articles from 2001 to 2013. Two limitations of existing research are identified: (1) the limited amount of studies relating to multi-layer transportation network vulnerability analysis, and (2) the lack of evaluation methods to explore the relationship between structure vulnerability and dynamical functional vulnerability. In addition to indicating that more attention needs to be paid to these two aspects in future, the analysis provides a new avenue for the discovery of knowledge, as well as an improved understanding of transportation network vulnerability.

Recent advances in modeling the vulnerability of transportation networks

In this paper we review the literature on multi-component maintenance models with economic dependence. The emphasis is on papers that appeared after 1991, but there is an overlap with Section 2 of the most recent review paper by Cho and Parlar (1991). The classification scheme that we choose is primarily based on the various options of grouping maintenance activities: grouping either corrective or preventive maintenance actions, or combining preventive maintenance activities with corrective actions. As such, this classification links up with the possibilities for grouped maintenance activities that exist in practice.

A Review of Multi-Component Maintenance Models with Economic Dependence

textA railway system needs a substantial amount of maintenance. To
prevent unexpected breakdowns as much as possible, preventive
maintenance is required. In this paper we discuss the Preventive
Maintenance Scheduling Problem (PMSP), where (short) routine
activities and (long) unique projects have to be scheduled in a
certain period. To reduce costs and inconvenience for the
travellers and operators, these activities have to be scheduled as
much as possible together. We present a mathematical formulation
for this problem and some greedy heuristics to solve it fast.
Moreover, we compare the performance of these heuristics with the
optimal solution using some randomly generated instances.

/pdf/scheduling-preventive-railway-maintenance-activities-2qhllwoyzd.pdf

Scheduling preventive railway maintenance activities

This paper presents the findings of a study looking into the valuation of travel time savings (VTTS) in Switzerland, across modes as well as across purpose groups. The study makes several departures from the usual practice in VTTS studies, with the main one being a direct representation of the income and distance elasticity of the VTTS measures. Here, important gains in model performance and significantly different results are obtained through this approach. Additionally, the analysis shows that the estimation of robust coefficients for congested car travel time is hampered by the low share of congested time in the overall travel time, and the use of an additional rate-of-congestion coefficient, in addition to a generic car travel time coefficient, is preferable. Finally, the analysis demonstrates that the population mean of the indicators calculated is quite different from the sample means and presents methods to calculate those, along with the associated variances. These variances are of great interest as they allow the generation of confidence intervals, which can be extremely useful in cost-benefit analyses.

Income and Distance Elasticities of Values of Travel Time Savings: New Swiss Results

The difficulties of engineers and managers agreeing on how to invest in infrastructure maintenance stem from a basic inability to communicate with each other. This leads to the suboptimal managemen...

/pdf/estimating-and-communicating-the-risk-of-neglecting-4xfexsto0j.pdf

Estimating and communicating the risk of neglecting maintenance

Railway managers identify and prioritize assets for risk-reducing interventions. This requires the estimation of risks due to failures, as well as the estimation of costs and effects due to interventions. This, in turn, requires the estimation of values of numerous input variables. As there is uncertainty related to the initial input estimates, there is uncertainty in the output, i.e., assets to be prioritized for risk-reducing interventions. Consequently, managers are confronted with two questions: Do the uncertainties in inputs cause significant uncertainty in the output? If so, where should efforts be concentrated to quantify them? This paper discusses the identification of input uncertainties that are likely to affect railway asset prioritization for risk-reducing interventions. Once the track sections, switches and bridges of a part of the Irish railway network were prioritized using best estimates of inputs, they were again prioritized using: (1) reasonably low and high estimates, and (2) Monte Carlo sampling from skewed normal distributions, where the low and high estimates encompass the 95% confidence interval. The results show that only uncertainty in a few inputs influences the prioritization of the assets for risk-reducing interventions. Reliable prioritization of assets can be achieved by quantifying the uncertainties in these particular inputs.

Identifying the Input Uncertainties to Quantify When Prioritizing Railway Assets for Risk-Reducing Interventions

Railway networks are constructed, maintained and developed to provide service to stakeholders. The timing of infrastructure interventions depends on the costs of intervening and the risks of not in...

https://www.icevirtuallibrary.com/doi/pdf/10.1680/jinam.18.00044

Defining and quantifying railway service to plan infrastructure interventions

Railways are critical infrastructure systems because their construction, use, operation, maintenance and development affect multiple stakeholders within society. To ensure that these systems functi...

https://www.icevirtuallibrary.com/doi/pdf/10.1680/jinam.19.00071

Natalia Papathanasiou

Papers

Estimating and communicating the risk of neglecting maintenance

Identifying the Input Uncertainties to Quantify When Prioritizing Railway Assets for Risk-Reducing Interventions

Defining and quantifying railway service to plan infrastructure interventions

Usefulness of quantifying effects on rail service when comparing intervention strategies

A network flow model to determine optimal intervention programs for railway infrastructure networks. DESTination RAIL Deliverable.