Weather-related Delays Research Articles

Evaluation of the Raw Material Purchasing Accounting System at PT Varia Usaha Beton

The rapid growth of the business world is forcing companies to adopt automation and efficiency to survive and compete. PT. Varia Usaha Beton, a concrete manufacturer, relies heavily on an accounting system for raw material purchasing to ensure efficient operations. The purpose of this research is to evaluate the company's raw material purchasing accounting system, identify problems and recommend improvements. The research method used is descriptive and qualitative with a case study approach. Primary data was obtained through interviews and observations, while secondary data was obtained through company documents. The research results show that the system works well and supports cost control, inventory management and quality monitoring. However, there are several vulnerabilities such as human error, technical issues with the ERP system, and weather-related delays in shipping raw materials. Recommended improvements include improved employee training, optimizing the ERP system, and developing more efficient inventory management. This research provides insights into the importance of evaluating accounting systems to improve the efficiency and effectiveness of business operations. Further research is recommended to conduct comparative analysis with other companies and explore new technologies to increase purchasing management transparency and efficiency

Quantifying weather-induced unreliable public transportation service in cold regions under future climate model scenarios

Climate change, particularly in cold regions, significantly challenges public transportation systems. This study conducts a comprehensive analysis of weather patterns and public transit reliability in the context of climate change impacts. Leveraging advanced modeling techniques, including a ridge regression model for snow water equivalent data estimation and a long short-term memory (LSTM) based on recurrent neural network, the study aims to assess the reliability trends of the rapid transit system under various climate scenarios. The findings reveal that climate change in general increases weather-related delays in the Toronto transit system. The number of short delays decreased accordingly due to changes in winter temperatures but exacerbated long delays as the number of weather extremes increased. The LSTM model performed effectively in predicting delays, especially for the rapid transit system sensitive to weather variations. This study emphasizes the need for robust planning and interventions to increase the resilience of transit systems against climate change and highlights the importance of the integration of climate and extreme weather considerations into transportation management.

A system dynamics model of offshore wind farm degradation: Enabling operation and maintenance planning under foreseen asset management impacts

This paper presents a system dynamics model to for the degradation of offshore wind farms (OWFs) optimise O&M planning and asset management, taking into account the effects of weather-related delays. The model predicts the future states of wind turbines, repairs, downtime expenses, failures, and production losses. Simulation results show the optimal scenario for effective intervention and the adaptability of the proposed model in controlling wind farm assets. By considering various maintenance planning approaches, the model identifies the factors affecting maintenance and minimises the impact of human response on O&M activities in OWFs.

Dangerous weather phenomena and their effect on en-route flight delays in Europe

Meteorological reports from Europe indicate that the number and intensity of summer thunderstorms are from year to year, gradually increasing. Climate change is seen as a difference in mean temperature and precipitation level and can lead to dangerous weather phenomena. This paper is driven by the idea to determine the impact of severe weather on air transport in Europe during the summer months. For the analysis, Performance Review Unit (PRU) Dashboard data from 2013 to 2019 were used. The more recent period was not considered due to the outbreak of the COVID-19 pandemic. The methodology covers the statistical analysis to confirm the theory. Research has shown that weather-related en-route delays are growing, influencing air transport’s future operation and economics. This paper also presents a medium-term forecast (3 years period) of the weather-related delays using the Exponential Triple Smoothing (ETS) Holt-Winters model. Based on the obtained outcomes, recommendations are presented in the conclusion.

Modeling free-flow speed variations under adverse road-weather conditions: Case of cold region highways

This study investigates driver behavior with respect to variations in desired driving speed under adverse road-weather conditions and explores the impacts of applying different data treatment methods in modeling such variations. The study site is located in a cold region highway in Alberta, Canada. The road-weather and traffic data collection devices are located alongside, permitting accurate measurement and association of exact pertaining road-weather and traffic conditions. The study has two main objectives: i) to investigate and model the impacts of road-weather events on the free-flow speed of vehicles, and ii) to explore the variability in models caused by adopting different data treatment methods. Linear and nonlinear regression models were developed with separate models for light and heavy vehicles travelling in shoulder and median lanes. Linear regression models developed with 20-minute aggregated free-flow speeds as dependent variable was found to be the best performing model for describing drivers’ choice of desired speed under adverse road-weather conditions. The study results revealed that slight, moderate and heavy snow will respectively reduce the free-flow speed of light vehicles travelling in the shoulder lane by 0.2%, 3.4% and 0.8%, and by 0.3%, 0.4% and 1.5% when travelling in the median lane. Moreover, heavy vehicles travelling in slight, moderate and heavy snow were estimated to reduce their desired speeds by 1.7%, 0.1% and 1.3% in shoulder lane while the reduction factors for those travelling in slight and moderate snow in median lane was 1.1% and 1% respectively. Estimated reduction factors for free-flow speed variations under adverse road-weather conditions found to be significantly smaller than HCM (2016) recommendations and the findings of other studies. These figures signify the importance of winter road maintenance in extremely cold regions. The frequent snow and ice removal as a result of winter road maintenance operations obviates the need for reducing desired speed and eventually results in less weather-related delays. The significance of driver familiarity with prevailing geographical conditions, i.e. winter driving was also highlighted when investigating the impact of inclement road-weather conditions on traffic operations.

Weather-Related Delay Provisions in Public Transportation Construction Contracts

Weather is one of the most volatile and unpredictable factors that can adversely affect construction works. Transportation projects are generally more susceptible to weather conditions because they are constructed outdoors and involve earthmoving operations. Contract provisions regarding weather-related delays in standard specifications published by the public transportation agencies are thus important, however, often deficient and unclear. The objectives of this paper are to analyze how public transportation agencies in the United States contractually deal with weather delays and provide a framework for stipulating weather-related provisions. The analysis was conducted by reviewing 20 different standard specifications: 18 state-level public transportation agencies (e.g., State Department of Transportation), American Association of State Highway and Transportation Officials (AASHTO), and the Federal Highway Administration (FHWA). This analysis is conducted on the basis of four key provision categories: (1) inclement weather aspects, (2) counting impacts to contract time by considering weather conditions, (3) indirect consequences of inclement weather, and (4) time extensions for weather delays. Specific recommendations are presented for each of the four categories as well as general recommendations that apply to all four.

RMetS National Meeting – Seasonal forecasting for the UK and Europe

RMetS National Meeting – Seasonal forecasting for the UK and Europe

Skillful Seasonal Forecasts of Winter Disruption to the U.K. Transport System

ABSTRACTThe impacts of winter weather on transport networks have been highlighted by various high-profile disruptions to road, rail, and air transport in the United Kingdom during recent winters. Recent advances in the predictability of the winter North Atlantic Oscillation (NAO) at seasonal time scales, using the Met Office Global Seasonal forecasting system, version 5 (GloSea5), present a timely opportunity for assessing the long-range predictability of a variety of winter-weather impacts on transport. This study examines the relationships between the observed and forecast NAO and a variety of U.K. winter impacts on transport in the road, rail, and aviation sectors. The results of this preliminary study show statistically significant relationships between both observed and forecast NAO index and quantities such as road-accident numbers in certain weather conditions, weather-related delays to flights leaving London Heathrow Airport, and weather-related incidents on the railway network. This supports the feasibility of the onward goal of this work, which is to investigate prototype seasonal forecasts of the relative risk of occurrence of particular impacts in a given winter for the United Kingdom, at lead times of 1–3 months. In addition, subject to the availability of relevant impacts data, there is scope for further work to make similar assessments for other parts of Europe and North America where the NAO has a strong effect on winter climate.

Low-Damage Posttensioned Segmental Bridge Columns with Flexible End Joints for Seismic Accelerated Bridge Construction

A computational parametric study leading toward the development of a new type of low-damage precast concrete segmental column for accelerated bridge construction in seismic areas is outlined. In contrast to conventional monolithic concrete construction, accelerated bridge construction significantly reduces on-site construction time, total project delivery time, weather-related construction delays, and environmental impact, and it provides improved work zone safety for the traveling public and contractor personnel and high product quality and durability. Low-damage systems provide significantly reduced postearthquake downtimes, repair costs, and casualties. The proposed column design will incorporate internal unbonded posttensioning and flexible joints at the column ends, where large flexural demands occur. These joints will be (flexurally) deformable enough to accommodate large column lateral deformations (drift ratios of 10% or higher) without damage, and (axially) stiff enough to limit initial axial deformations due to initial posttensioning and gravity loads. To investigate this concept, a three-dimensional finite element model of a cantilever segmental concrete column incorporating a flexible joint segment at the bottom was generated, and a comprehensive parametric study was conducted. The parametric study investigated three types of polyurethane elastomers for the flexible joint and various geometric properties of the flexible joint in reference to the column geometry. The findings of this study, as supported by preliminary material testing, have shown that hyperelastic materials, such as stiff rubbers and polyurethanes, are good candidates for the proposed application.

On the use of a steerable main landing gear for crosswind landing assistance

Several crosswind-related incidents show that landing under heavy crosswind conditions can be challenging for pilots and may pose a threat to aviation or at least lead to higher pilot workload and/or irregularities in operations. For transport aircraft the common approach technique for crosswind landings is the so-called crabbed approach with wings level and a windward heading correction. This technique requires alignment of the aircraft with the runway prior to touchdown in order to keep lateral loads of the landing gear and tyres as low as possible and to maintain the controllability on ground after touchdown. The German Aerospace Center Institute of Flight Systems has used the idea of steerable main gears and developed a crosswind landing assistance system. During approach all gear struts are automatically aligned with the runway so that no decrab manoeuvre is required. On ground the assistance system uses each steerable landing gear, differential braking, and the aerodynamic control surfaces to control and stabilise the aircraft. After touchdown the aircraft is automatically aligned with the runway centreline and the still existing crab angle is slowly reduced. A simulator study with pilots in the loop using a model of a typical medium range transport aircraft was conducted in order to evaluate the benefits of such a landing technique. The study revealed that not only the aircraft controllability could be improved by landing in crabbed motion under strong crosswind conditions, but that the side forces acting on the landing gear can be reduced significantly as well. It was also shown that the use of steerable main landing gears is able to enlarge the spectrum of autoland operations, which is relatively limited at present in terms of maximum allowable crosswinds. All together the system has shown to be able to improve flight safety, lower the risk of weather-related delays due to go-arounds or diversions, and it also reduces structural loads on the landing gear during touchdown and landing.

Below the Horizon

This article elaborates the advantages of underground nuclear parks over conventional nuclear power plant designs. Locating the reactors a few hundred feet underground in bedrock at a suitable site eliminates the need for containment structures, and the site would be largely impervious to physical attack from terrorists. (Indeed, it would be far easier to secure the few access points to an underground nuclear park than it is to protect the large perimeter of an isolated nuclear power plant.) A properly constructed underground facility would also be less subject to weather-related construction delays or the effects of hurricanes, tornadoes, flooding, or heat waves. Also, if designers were careful in the site selection, an underground nuclear park could virtually eliminate the transportation of hazardous nuclear waste material. Spent nuclear fuel could be moved via tunnel from the reactors to an array of storage tunnels; high-level waste could be permanently stored in another set of tunnels. When the reactors reach the end of their productive life, they can be decommissioned in place.

Integrated Framework for Quantifying and Predicting Weather-Related Highway Construction Delays

Constant exposure to the environment makes highway construction highly dependent on weather. However, highway construction contracts are often unclear about the potential influence of weather-related delays on highway construction project schedules. There is a need to discourage litigation arising from weather-related delays by including in contracts a reasonable number of nonwork days as a consequence of adverse weather and providing an equitable criteria for the course of action when the predictions in the contracts turn out to be inaccurate. To address this need, an integrated framework consisting of the following two key components is proposed: (1) identification of attributes of weather that cause construction delays and (2) generation of synthetic weather sequences using a stochastic weather generator to quantify and provide probabilistic forecasts of weather threshold values. The utility of this framework is demonstrated through its application to construction work on a project in Texas. The use of probabilistic forecast of construction delay attributes provided by a semiparametric weather generator in this research is an example of interdisciplinary study to help address this problem. The result of the research is better decision support for agencies who wish to author contracts that more equitably allow for the influence of weather during construction.

Automatic identification of risky weather objects in line of flight (AIRWOLF)

Adverse weather conditions are hazardous to flight and contribute to re-routes and delays. This has a negative impact on the National Airspace System (NAS) due to reduced capacity and increased cost. In today’s air traffic control (ATC) system there is no automated weather information for air traffic management decision-support systems. There are also no automatic weather decision-support tools at the air traffic controller workstation. As a result, air traffic operators must integrate weather information and traffic information manually while making decisions. The vision in the Next Generation Air Transportation System (NextGen) includes new automation concepts with an integration of weather information and decision-making tools. Weather-sensitive traffic flow algorithms could automatically handle re-routes around weather affected areas; this would optimize the capacity during adverse conditions. In this paper, we outline a weather probe concept called automatic identification of risky weather objects in line of flight (AIRWOLF). The AIRWOLF operates in two steps: (a) derivation of polygons and weather objects from grid-based weather data and (b) subsequent identification of risky weather objects that conflict with an aircraft’s line of flight. We discuss how the AIRWOLF concept could increase capacity and safety while reducing pilot and air traffic operator workload. This could translate to reduced weather-related delays and reduced operating costs in the future NAS.

Factors Affecting the Frequency and Severity of Airport Weather Delays and the Implications of Climate Change for Future Delays

This paper evaluates the impact of changing weather on air transportation operations over the coming 50 years by using London's Heathrow Airport as a case study. The weather parameters associated with weather-related delays at Heathrow are first identified, and statistical models for the occurrence and the severity of weather-related delay events are then presented. Thunderstorms, snow, and fog are found to increase the chance of weather-related delay by more than 25%, whereas an increase in wind speed of 1 knot above the mean increases the probability of delay by 8%. The severity of delay can be classified correctly in 84% of cases by using nine weather predictors. These statistical models are then used in conjunction with climate forecast data to estimate future weather-related delays. Seven climate models were used to calculate changes in weather parameters in the 2050s for three emissions scenarios. The climate model outputs limit the range of weather parameters that can be forecast; for those that cannot be included in the model, a qualitative assessment of their potential impact on airport delay is provided.

Short-Term Delay Mitigation Strategies for San Francisco International Airport

San Francisco International Airport (SFO) is typical of many large airports in that rapid growth in air travel has outpaced its available runway capacity, leading to serious delays. At the same time, SFO represents a unique circumstance because of the role of its local climate, and thus careful analysis is required to address its delay situation. The airport is in the process of planning a major runway reconfiguration project that would largely solve the problem of weather-related congestion delays, but this massive project will take many years. Presented are the results of an effort to design potential short-term strategies to reduce weatherrelated congestion delay at SFO while the runway reconfiguration proceeds. Designing measures to reduce delay outside the context of runway expansion is a complex task that requires balancing multiple considerations—issues of equity, access, legal jurisdiction—along with considerations of efficiency and airport performance. The kinds of thinking and analysis required in considering these types of delay-reduction measures are explored.

Nowcasting for Space Shuttle Landings at Kennedy Space Center, Florida

Space shuttle launches and landings at Kennedy Space Center (KSC) are subject to strict weather-related launch commit criteria and landing weather flight rules. Complex launch commit criteria and end-of-mission landing weather flight rules demand very accurate forecasts and nowcasts (short-term forecasts of less than 2 h) of cloud, wind, visibility, precipitation, turbulence, and thunderstorms prior to shuttle launches and landings. The challenges to the National Weather Service Spaceflight Meteorology Group forecasters at Johnson Space Center to nowcast and forecast for space shuttle landings and evaluate the landing weather flight rules are discussed. This paper focuses on the forecasts and nowcasts required for a normal end-of-mission and three scenarios for abort landings of a space shuttle at KSC. Specific weather requirements for a potential emergency landing are the dominant cause of weather-related delays to space shuttle launches. Some examples of meteorological techniques and technologies in support of space shuttle landing operations are reviewed. Research to improve nowcasting convective activity in the Cape Canaveral vicinity is discussed, and the particular forecast problem associated with landing a space shuttle during easterly flow regimes is addressed.

Refining the On-Line Scholar's Tools

Three months ago, Science began the second phase of our World Wide Web system for distributing information (see [ Science , 3 November 1995][1]). With that issue, users of Science 's on-line counterpart (at URL ) were given new tools developed in collaboration with [HighWire Press][2] of Stanford University. As early as 5:00 p.m. eastern time on the day before the cover date, readers of the Science On-Line Web pages could search through the cumulative archives (back to 6 October 1995) of abstracts of all published Articles, Reports, Perspectives, and Policy Forums, as well as summaries of Research News and News and Comment items. Tables of Contents were also viewable back to 23 June 1995, when this digital campaign was launched. Our general objective in developing these features is to exploit the digital media channels and help readers navigate, select from, and organize the seas of information they confront daily. In the next few weeks, we will be introducing additional tools. Although many of our print readers may still be skeptical that such Web mania can meet their needs in scientific data gathering and analysis, we believe that we can significantly augment the value of the print journal through these new media, especially for readers in locations where mail delivery may be problematic or for whom rapid access to new and past items may be important. Without giving away all of the features under development, we would like to provide enough detail about our future general direction to entice additional readers to sample our digital wares, along with the print offerings. In the near future, we will be sampling readers' interest in obtaining the full text of our Articles, Reports, News, and other items. We will also be providing more than the full text by delivering information that would not fit in the limited pages of a printed issue of Science . Now in active testing are automated software features that will establish hyperlinks to other data and information sources that are relevant to a printed item, a capability that is well beyond what can be done with printed-paper technology. Under consideration is the possibility of allowing authors to link addenda to their papers, so that they can report less formally on subsequent findings related to their original ones and do so well before a new submittal could make its way through our peer review system or that of another journal. Such temporally evolving searchable threads transcend the usefulness of printed notes. The next steps will also provide some new ways to satisfy the hungers of those who track new books on science-related issues. In addition, we believe that the on-line media may allow more readers to respond with letters to editors and authors, which can later be excerpted for print-only readers. The next set of on-line tools and services has already been thoroughly tested with active lab scientists to ensure that those tools are not only usable but also provide truly useful features, whether a reader wants to search for Science papers, news, product ads, or job opportunities. The costs of taking these next steps will initially be borne by leading-edge advertisers who want to bring their name, products, and services to the attention of the Internet-savvy scientific community. The intent throughout the developmental stages has been to keep the advertising informative and accessible. The electronic channels available to Science readers are also facilitating the ways in which we receive, review, and decide on submittals, and in fact helped our dedicated staff survive the blizzard of 1996 and get the 12 January issue out almost undelayed. Staff walked in (one trudged 6 miles), skied in, or endured extremely long commuting times to ensure that a core group was here every day to keep the editorial and advertising pages on schedule for three different issues. Phones, faxes, modems, and e-mail provided a virtual office, allowing many of those stuck at home to work with those who made it in. New electronic procedures still in the test phase proved their worth under fire. These electronic tools, combined with an extremely dedicated and determined staff, allowed us to complete, with considerable improvisation, the final production steps for the 12 January issue. Our publication vendors, Cadmus Journal Services in Richmond, Virginia, and Brown Printing Company in Waseca, Minnesota, pulled out all the stops to overcome any weather-related delays in the production process. In the end, all domestic shipments were on time, with less than a 24-hour delay in shipments to Canada and Europe. It's a new era for both readers and editors. Come try us. [1]: http://highwire.stanford.edu/science/content/vol270/issue5237/ [2]: http://highwire.stanford.edu/

Incorporating the Impacts of Uncertain Fieldwork Time on Whole-Farm Risk-Return Levels: A Target MOTAD Approach

AbstractGiven an equipment complement, a specific crop mix has a probability distribution for whole-farm net returns. Increasing crop acreage while holding the set of equipment constant will reduce fixed costs per acre, but it will also increase the length of time required to complete crucial field operations such as planting and harvesting. Thus, the probability of encountering weather-related delays in fieldwork will increase. This increase in delays may cause a decline in yields and changes in the distribution of net returns. This paper develops a Target MOTAD model capable of capturing intra-year impacts on profit that arise from the timing of planting and harvesting operations as well as inter-year impacts on profits that are due to variations in economic and weather-related factors. The model relies on estimates of available fieldwork time and a crop's harvestable yield in different time periods throughout the harvest season.