Development of a Rule-Based Finite Capacity Scheduling System

This paper discusses the use of the finite capacity planning model as a basis for a job-shop scheduling system. The suitability of this approach for constructing short term schedules with very short lead times is examined. This paper introduces a rule-based scheduling system whose operation, unlike previous monolithic schedulers, is based around distinct though interlinked processes. Scheduling herein is defined as the selection of a set of orders for manufacture, and the allocation of processing time to each on an acyclic network of processing resources. The objectives are, firstly, compliance with all customer deadlines and, secondly, the efficient utilisation of available machine time and prevailing machine setups

A specified procedure for distress identification and assessment for urban road surfaces based on PCI

In this paper, a simplified procedure for the assessment of pavement structural integrity and the level of service for urban road surfaces is presented. A sample of 109 Asphalt Concrete (AC) urban pavements of an Italian road network was considered to validate the methodology. As part of this research, the most recurrent defects, those never encountered and those not defined with respect to the list collected in the ASTM D6433 have been determined by statistical analysis. The goal of this research is the improvement of the ASTM D6433 Distress Identification Catalogue to be adapted to urban road surfaces. The presented methodology includes the implementation of a Visual Basic for Application (VBA) language-based program for the computerization of Pavement Condition Index (PCI) calculation with interpolation by the parametric cubic spline of all of the density/deduct value curves of ASTM D6433 distress types. Also, two new distress definitions (for manholes and for tree roots) and new density/deduct curve values were proposed to achieve a new distress identification manual for urban road pavements. To validate the presented methodology, for the 109 urban pavements considered, the PCI was calculated using the new distress catalogue and using the ASTM D6433 implemented on PAVER TM. The results of the linear regression between them and their statistical parameters are presented in this paper. The comparison of the results shows that the proposed method is suitable for the identification and assessment of observed distress in urban pavement surfaces at the PCI-based scale

Railway infrastructure condition-monitoring and analysis as a basis for maintenance management

Suvremene željeznice danas troše oko pedeset tisuća eura na godinu po kilometru kolosijeka za održavanje i remont. Uštede koje se mogu postići pomoću suvremenog odlučivanja zasnovanog na mjerenju i analizi stanja, primijenjenog kroz adekvatni informacijski sustav za podršku odlučivanju, procjenjuju se u rasponu od skromnih 15 % do optimističkih 55 %. U radu se daje opis najznatnijih metoda za mjerenje stanja željezničke infrastrukture u primjeni danas u svijetu, kao i opis procesa analize izmjerenih podataka radi upravljanja radovima na održavanju i remontu.Average annual maintenance and renewal (M&R) expenditures per 1 km of tracks of advanced railway networks nowadays revolve around EUR (€) 50.000. Estimated cost-savings resulting from the use of a modern condition-based decision-making approach, embedded in a suitable decision-support information System, are reported to range from modest 15 % up to the optimistic 55 %. Most important railway track condition-monitoring methods applied worldwide are described, and a data analysis process used for the M&R management purposes is presented

Strategies for maintenance management of railway track assets

M.Ing. (Engineering Management)Abstract: Population growth and environmental issues are revitalizing the railway sector in a tremendous way. An increase in frequency of passenger traffic and rising loads of freight trains has an impact on dynamic railway track properties and components thereof. The challenge from the railway fraternity is to rise to the challenge by ensuring a safe, reliable and affordable mode of transport. The purpose of this research is to investigate the capacity needed to meet demand by maintaining the track components of the railway infrastructure cost effectively. The railway track is the most critical in terms of safety, influence on maintenance costs, availability and reliability of the train service. Profillidis (2012) highlights the fact that track maintenance expenses represent a significant percentage of total railway infrastructure expenses. In literature, different maintenance strategies, approaches and concepts are discussed in light with arguments raised by different scholars and researchers. The main research methodology utilised was the case study on maintenance strategies from different countries where data was mostly available. The reason for the chosen method was to standardise the research method across different countries as this made it easy to obtain the findings and arrive at recommendations of the research. The broader findings from different maintenance strategies were that the track maintenance approach still has to evolve from working in silos to working in a system that acknowledges that decisions taken from other departments can affect the quality of maintenance in future. The deterioration of the track system is mostly affected by the initial quality of the railway track after commissioning due to workmanship and track design, maintenance approach, type of rolling stock tonnages, speed of rolling stock, and environmental related issues. Design phase of the track acknowledges the systems thinking approach for quality and structural integrity. However, more can still be done to adopt approaches that foster inter-departmental coordination in the maintenance phase of the railway track asset lifecycle. Transnet faces a challenge of fulfilling its obligation by providing quality and cost effective maintenance to increase the reliability, affordability, availability and safety of its infrastructure with the ever-increasing freight volumes. The traditional approach of maintaining railway track assets does not bring in required outcomes that ensure high quality and cost effective maintenance as required by high intensity asset utilisation. Data collected from the..

Non-destructive assessment and health monitoring of railway infrastructures

A continuous increase of the demand for high-speed traffic, freight tonnage as well as of the train operating frequency is worsening the decay conditions of many railway infrastructures. This occurrence affects economy-related business as well as it contributes to raise maintenance cost. It is known that a failure of a railway track may result in tremendous economic losses, law liabilities, service interruptions and, eventually, fatalities. Parallel to this, requirements to maintain acceptable operational standards are very demanding. In addition to the above, a main issue nowadays in railway engineering is a general lack of funds to allow safety and comfort of the operations as well as a proper maintenance of the infrastructures. This is mostly the result of a traditional approach that, on average, tends to invest on high-priority cost, such as safety-related cost, compromising lower-priority cost (e.g., quality and comfort of the operations). A solution to correct this trend can be to move from a reactive to a proactive action planning approach in order to limit more effectively the likelihood of progressive track decay. Within this context, this paper reports a review on the use of traditional and non-destructive testing (NDT) methods for assessment and health monitoring of railway infrastructures. State-of-the-art research on a stand-alone use of NDT methods or a combination of them for specific maintenance tasks in railways is discussed

Design and validation of a railway inspection system to detect lateral track geometry defects based on axle-box accelerations registered from in-service trains

Metropolitan railway transport has become an efficient solution to the mobility necessities in urban areas. Railway track maintenance tasks have to be improved and adjusted to metropolitan requirements, in particular the few hours available to operate due to the high frequency service offered. This paper describes and proposes an inertial monitoring system to detect and estimate track irregularities by using in-service vehicles. A new maintenance strategy is established, based on the railway track conditions and continuous monitoring is provided to do so. The system proposed consists of at least two accelerometers mounted on the bogie axle-box and a GPS (Global Positioning System). Lateral accelerations have been analyzed to study gauge and lateral alignment deviations. Accelerations have been treated and processed by high-pass filtering and validation has been carried out by comparison with measurements provided by a track monitoring trolley. Measurements were made on Line 1 of the Alicante metropolitan and tram network (Spain)

Understanding the Effects of Climate on Airfield Pavement Deterioration Rates

Over the past two decades, pavement engineers at the Air Force Civil Engineer Center have noticed the majority of identified distresses from PCI airfield surveys are climate related. To verify these trends, a comprehensive analysis of the current airfield pavement distress database was accomplished based on a climate region perspective. A four-zone regional climatic model was created for the United States using geospatial interpolation techniques and climate data acquired from WeatherBank Inc. Once the climatic regional model was developed, the climate information for each installation was imported into the Air Force pavement distress database within PAVER. Utilizing the pavement condition prediction modeling function in PAVER, pavement deterioration models were created for every pavement family at each base in each climatic zone. This was done to generate a list of bases that may have multiple pavement families with rates of deterioration that are better or worse than the regional rates of deterioration. The average regional rates of deterioration for each pavement family were found to be within the parameters of conventional wisdom observed in Asphalt Concrete (AC) and Portland Cement Concrete (PCC). The results of the pairwise comparisons using the Student\u27s T-test determined the Freeze-Dry climate region deterioration rates for the PCC pavement family were statistically different than the other three regions. No significant statistical differences were observed in the AC pavement comparisons. This analysis established a foundation to investigate and identify variables causing the rates of deterioration at specific installations to differ from the regional rates of deterioration

Methodology for urban rail and construction technology research and development planning

A series of transit system visits, organized by the American Public Transit Association (APTA), was conducted in which the system operators identified the most pressing development needs. These varied by property and were reformulated into a series of potential projects. To assist in the evaluation, a data base useful for estimating the present capital and operating costs of various transit system elements was generated from published data. An evaluation model was developed which considered the rate of deployment of the research and development project, potential benefits, development time and cost. An outline of an evaluation methodology that considered benefits other than capital and operating cost savings was also presented. During the course of the study, five candidate projects were selected for detailed investigation; (1) air comfort systems; (2) solid state auxiliary power conditioners; (3) door systems; (4) escalators; and (5) fare collection systems. Application of the evaluation model to these five examples showed the usefulness of modeling deployment rates and indicated a need to increase the scope of the model to quantitatively consider reliability impacts