Browsing by Author "Black, Ian G."
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Item Open Access Airline schedule punctuality management(Cranfield University, 1991-03) Al-Haimi, Abdullah A.; Black, Ian G.Airline schedule punctuality is a complex problem and one of the major concerns of the airline top management. Flight schedule disturbances may occur as delays and/or cancellations. There are many internal and external reasons for delays. These delays may propagate in the aircraft cycles and cause a large schedule disturbance. This may influences passenger satisfaction and airline resources. The objective of this research is to formulate a systematic approach for schedule punctuality which supports management decision making. The punctuality management system is structured to combine all schedule punctuality components, input and output variables. Five models are incorporated in this system. The first model is the disturbance model which generates random delays based on an estimated Lognormal delay distribution function. The delay analysis is carried out from a one year sample of delay statistics in which general, original , reactionary and other delay types are classified. The second model is the recovery model which incorporates the disturbance model with management strategies to determine delay propagation. A PC based simulation model (SKDMOD) is developed as a prototype which integrates disturbance and recovery models using SIMSCRIPT 11.5. 18 management strategies are simulated covering ground times (30, 40 and 50 minutes), maximum delay times to assign spare aircraft (1, 2, 3, 4, 5, and 6 hours) and spare aircraft using part of the domestic network of Saudi Arabia. The third model is the passengers' attitude model which determines the delay impact functions and the maximum passenger revenue loss based on 262 responses from a passenger interview survey. The fourth model is the revenue model which estimates the passengers' revenue loss. The fifth model is the cost model which estimates the extra cost resulting from implementation of the management strategies. All strategies are evaluated to determine the optimum based on profit and profit margin. OPTIM is the optimization program developed to find the optimum strategy(ies). This approach provides a guidelines for the management of punctuality. It integrates all the tools developed in a decision support system framework.Item Open Access The effect of intangible product attributes on rail passenger demand with special reference to ride quality(Cranfield University, 1990-03) Harrell, Lawrence; Black, Ian G.This study set out to investigate the value consumers place on less tangible product attributes. Although some work has been done in the p ast, to establish the relative importance of intangible attributes; very few studies have attempted to produce a financial value for a change. The research was conducted in a rural railway environment and so the product considered was a train journey. The main intangible attribute chosen for the study was ride quality. Rural railway services make significant losses and as a result have been threatened with closure. Reducing track maintenance (and thus ride quality ) on these routes offers considerable scope for cost reduction. But, very little was known about the response of demand to changes in ride quality. Any results obtained could, therefore, make a contribution to maintaining railway services in areas of limited public transport. Although this study concentrated on the railway ride problem, it is believed that the method developed during this research would be applicable, with some modification, to other topics.Item Open Access The effect of time-window constraints and fleet size on the cost of a distribution operation(Cranfield University, 1991-05) Barham, P. A. J.; Black, Ian G.Adopting a Continuous Space Modelling-type scenario of no detailed data being available at a customer-specific level, and on the basis, therefore, of basic information on delivery-area size, total number of locations to be visited and average road-speeds etc., quantitative expressions are derived for, the relationship between the number of vehicles operating from a central depot and the total fleet mileage that is required to visit a set of locations, and, 2. the effect of time-window constraints on the total cost of a similar operation. These expressions are derived using a simulation-based methodology, involving the setting-up of a computer program which both generates Travelling-Salesman tours and provides information on these tours at a detailed, disaggregated level. In the time-constrained context, it was necessary to develop a heuristic route-building procedure for solving Travelling-Salesman Problems due to the algorithmicItem Open Access Estimating the monetary value of airport runway departure slots(1996-10) Pagliari, Romano Italo; Black, Ian G.Slot allocation is one of the most contentions and keenly debated topics within the air transport industry. The issue of pricing access to airport slots, as a means of relieving congestion, has received increased attention in recent years. However, little attempt has been made to determine how airlines value access to slots, or to measure the impact quantitatively of introducing the pricing mechanism into slot allocation. It is the objective of this thesis to establish a process whereby the potential value of a slot can be determined. Since the value of a slot is ultimately a function of the how highly passengers value travelling at different times of the day, the research problem is initially approached from the passenger’s perspective. Analysis focused initially on the use of stated preference methods, to derive parameters which measure how highly passengers value different departure times. These parameters were then calibrated on a departure time choice model, which estimates, given assumptions on the distribution of ideal departure times on a given route, how passengers select flights scheduled at different times. Decision-rules governing the scheduling of profitable flights were developed. These rules determine the conditions necessary for the scheduling of profitable flights and the setting of fares. Combining both passenger and flight scheduling decision-rules within a simulation model it was then possible to generate, given various assumptions on aircraft size and total demand, a set of equilibrium flights scheduled at different departure times, associated with a level of passenger demand and equilibrium fare. From these simulations, slot value estimates were derived. Within the context of the thesis objective, analysis focused on a wide range of issues. These were: stated preference experimental design and parameter estimation, how passengers value departing at different times of the day, competition for slots, time of day pricing, and estimating potential slot values for different aircraft types. This thesis has contributed to existing literature on slot allocation through firstly; outlining a method to estimate slot values, secondly, providing a more thorough analysis of passenger departure time preferences in air transportation, and thirdly, a further demonstration of the application of stated preference techniques within an aviation context.Item Open Access An investigation into the notions of 'success' and 'failure' held by senior UK airline executives and their perceptions of the causes of 'success'(Cranfield University, 2003-12) Beech, J. G.; Black, Ian G.This study explores the notions of 'success' and 'failure' held by senior executives in the UK and Irish airline industry. Previous studies of this industry have tended to be from a positivist perspective, focusing on financial performance at the level of 'airline' or 'airline industry'. This study takes the airline executive as the unit of analysis and is conducted from a phenomenological perspective. A methodology using interviews, causal mapping and postal questionnaires is applied to surface the notions of 'success' and 'failure' and the perception of the causes of 'success' held by board-level airline executives. Standardised data published by the Civil Aviation Authority Economic Research Group is used to establish a range of objective measures, both financial and operational, and these objective measures are compared with the rankings of the senior executives' perceptions of the success of UK and Irish airlines. The research establishes that senior airline executives do not see 'success' in terms of financial objective measures such as Added Value or Operating Ratio; they use profit as the primary financial measure of 'success' and frequently hold notions of 'success' that are based in other functional areas such as operations and marketing. The causes of 'success' are seen as coming from the breadth of functional areas. The influence of HRM factors becomes clearer at deeper levels of abstraction when considering 'success'. There is limited evidence of the stereotyping of perceptions when the success of specific airlines is considered, but not for airlines' success in general. Recommendations for further research into the management of human resources within airlines are made.Item Open Access The marginal social cost of road and rail: Implications for rail investment and pricing(Cranfield University, 1995-08) Al-Tony, Fathy El-Sayed; Black, Ian G.An important issue for transport policy is whether more investment should be devoted to rail schemes and less to road schemes and vice versa. This raises the problem of comparing the returns from investments in the two modes currently assessed on a different basis - road schemes are appraised on a Cost Benefit Analysis (CBA) basis, whereas rail schemes are assessed on a Financial Analysis (FA). This study is a step in the direction of identifying the difference between the two techniques (CBA and FA) of appraisal in general and in case of rail investment in particular, and examining the implications of the use of the two different techniques in assessing the investment in road and rail. In addition, the study develops a methodology for assessing rail investment schemes that could be consistent with the cost benefit analysis being used in assessing road investment projects. The differences between CBA and FA are identified. The current practice of assessing road and rail investment schemes is examined and the weaknesses are outlined. The potential implications of assessing road and rail investment on different criteria are explored. Previous rail investment studies where both CBA and FA were undertaken are reviewed and discussed to explore how the task of CBA were carried out to rail schemes and to show the difference with the current study approach. The study framework of rail scheme appraisal is identified to include four elements of impacts. These are; financial impacts to the rail operator (producer surplus), rail user benefits (consumer surplus), non-user benefits, and other impacts on other bodies in the society (tax adjustments). Non-user benefits concerned by the study are road congestion time, noise, air pollution, accidents, and vehicle operating costs. Road congestion time, noise and air pollution are identified as externalities, while accidents and vehicle operating costs are dealt with as cases of cost misperception. The five items of non-user benefits are measured at the margin in a process to identify the Marginal Social Cost (MSC) of travel as a function of the road type alternative. Eight types of road are identified for the study to represent the entire UK road network. The measurement process of non-user benefits incorporates the variation in traffic over time and place. This is carried out by incorporating four traffic distributions in the calculation process. The distributions of traffic reflect traffic variations from hour to another (24 hours) throughout the day, from day to another (7 days) throughout the week, from month to another (12 months) throughout the year and from location to another throughout the UK entire road network. The implications of the study findings are explored. Three undesirable implications are identified. These are welfare losses to the society, lower share for rail travel, and investment bias towards roads. Three policy options are put as a solution. These are, pricing road and rail services according to the MSC, subsidising public transport, and applying a consistent appraisal method for road and rail investment. The contribution of these options towards achieving a sustainable balance between road and rail as well as their applicability in practice are examined. At the end some improvements and attached areas of further research are suggested.Item Open Access Modelling dynamic stochastic user equilibrium for urban road networks(Cranfield University, 1991-01) Vythoulkas, Petros C.; Black, Ian G.In this study a dynamic assignment model is developed which estimates travellers' route and departure time choices and the resulting time varying traffic patterns during the morning peak. The distinctive feature of the model is that it does not restrict the geometry of the network to specific forms. The proposed framework of analysis consists of a travel time model, a demand model and a demand adjustment mechanism. Two travel time models are proposed. The first is based on elementary relationships from traffic flow theory and provides the framework for a macroscopic simulation model which calculates the time varying flow patterns and link travel times given the time dependent departure rate distributions; the second is based on queueing theory and models roads as bottlenecks through which traffic flow is either uncongested or fixed at a capacity independent of traffic density. The demand model is based on the utility maximisation decision rule and defines the time dependent departure rates associated with each reasonable route connecting, the O-D pairs of the network, given the total utility associated with each combination of departure time and route. Travellers' choices are assumed to result from the trade-off between travel time and schedule delay and each individual is assumed to first choose a departure time t, and then select a reasonable route, conditional on the choice of t. The demand model has therefore the form of a nested logit. The demand adjustment mechanism is derived from a Markovian model, and describes the day-to-day evolution of the departure rate distributions. Travellers are assumed to modify their trip choice decisions based on the information they acquire from recent trips. The demand adjustment mechanism is used in order to find the equilibrium state of the system, defined as the state at which travellers believe that they cannot increase their utility of travel by unilaterally changing route or departure time. The model outputs exhibit the characteristics of real world traffic patterns observed during the peak, i. e., time varying flow patterns and travel times which result from time varying departure rates from the origins. It is shown that increasing the work start time flexibility results in a spread of the departure rate distributions over a longer period and therefore reduces the level of congestion in the network. Furthermore, it was shown that increasing the total demand using the road network results in higher levels of congestion and that travellers tend to depart earlier in an attempt to compensate for the increase in travel times. Moreover, experiments using the queueing theory based travel time model have shown that increasing the capacity of a bottleneck may cause congestion to develop downstream, which in turn may result in an increase of the average travel time for certain O-D pairs. The dynamic assignment model is also applied to estimate the effects that different road pricing policies may have on trip choices and the level of congestion; the model is used to demonstrate the development of the shifting peak phenomenon. Furthermore, the effect of information availability on the traffic patterns is investigated through a number of experiments using the developed dynamic assignment model and assuming that guided drivers form a class of users characterised by lower variability of preferences with respect to route choice.Item Open Access Multi-equation travel demand models application to the air-rail competition in Great Britain(Cranfield University, 1981-10) Cherif, T; Black, Ian G.The main purpose of this research is to develop a set of econometric Air-Rail competition models which are sufficiently sensitive to measure the effects upon demand of policy decisions, with regard to such variables as frequency of services and fares. Existing Modal Competition Models have, rather uncritically, applied Multiple Regression analysis in considering only one aspect of the market, namely the demand for travel, ignoring therefore the effects of the supply upon the demand. The emergence of the so called "Simultaneous Equations Bias", due to the two-way dependency between the demand and the level of service factor expressing the supply, renders the application of the 015 (Ordinary Least Squares) inappropriate, and hence, yields biased, inconsistent, and inefficient OLS coefficients. The models, developed in this study, depart from all existing Modal Competition Models, and overcome some of their drawbacks. They are formulated as Multi-equation Supply/Demand Modal Competition Models. They introduce the frequency of services variable not only in the demand, but also in the supply equation expressing the level of supply in response to changes in other variables. In order to derive unbiased, more conSistent, and more efficient coefficients, sophisticated statistical techniques, such as 2315 and JSLS (Two-Stage Least Squares and Three-Stage Least Squares) • are applied as a means of calibration. The elasticities obtained are consistent with the Supply and demand Microeconomic Theory. The frequency of services appears as the most powerful explanatory variable in Air demand; whereas fare and income are the most powerful variables in Rail demand equation. This leads to the conclusion that Air mode is mainly higher income groups and/or business oriented market; and Rail mode lower income groups and/or personal oriented market. Furthermore, Air and Rail are competing on a fare basis in short routes; while they do not show close substitutes for each other in longer ones. The high significance of the frequency of services, in Air demand, outlines its importance as a factor influencing the demand, and therefore, provides the Airlines management with the capability of improving the demand by acting upon the endogenous factor. This is of great interest in the scheduling fleet process. Similarly, the significance of Rail fare variable offers the Railways management the possibility of acting upon the demand through this controlable variable, for an efficient pricing policy. Rail journey time elasticities, derived from these models, are very close to the elasticities assumed by British Railways Board, in their Passenger Traffic Model, 1980. The statistical results indicate that the elasticities derived are useful for both analysis and forecasting purposes.Item Open Access Noise landing charges and passengers' choice of airport.(Cranfield University, 1995-04) Yeahiya, Mohammed; Black, Ian G.This study demonstrates how aircraft noise can be translated into a form of landing charge. The objectives of the thesis were to develop noise landi'ng charges for six of the major airports in England and to determine what the implication it has on passengers' choice of airports. An airport choice model is developed distinguished by three market types: long-haul international scheduled, short-haul international scheduled and charter international. Modelling of airport choice was also carried out for passengers from the Greater London and South East areas. The best results are obtained using difference in access time, logarithmic difference in frequencies and weighted differences in fare variables. There is consistency in the access time coefficients for all three markets. Airport choice for international scheduled and charter passengers for the Greater London and other South East areas also show consistency in access time amongst different passenger groups in choosing airports. The implication of the noise charge particularly at Gatwick and Heathrow for the short and long haul markets reveal that the fare coefficients are sensitive and are subject to doubt. However Brooke et al (1994) acknowledge that exact fare details are difficult to obtain. Therefore it is a difficult task to produce accurate fare coefficients with published fare details that do not take into account discounts received by passengers. This is reflected in this study by observing the fact that high number of passengers change airports, when it may be argued that the noise charges are moderate. The sensitivity of the implications of the noise charge determined in this study have depended highly on the fare coefficients. This study has demonstrated the importance and perhaps the over reliance of depending on a single parameter for the evaluation of the implications of the noise charge.Item Open Access The role of third party logistics providers in Europe - A combined network and systems approach(Cranfield University, 2002-11) Jockel, Otto; Black, Ian G.Third party logistics is a concept that is widely accepted as an alternative to vertical integration. The degree to which it is applied in practice varies considerably. The focus of this research is the role of TPLPs in existing logistics systems, and how they themselves can influence this. This is influenced by the strategic position with which a TPLP is trusted by a shipper, and to some extent by a TPLP's competence and entrepreneurial behaviour towards logistics management. Logistics competence is sourced externally up to the level at which a shipper recognises this to be advantageous. TPL involvement might be influenced by TPLPs' initiatives towards innovative ideas in logistics management. The objectives of this research were to explore different roles that TPLPs can assume in the management of their clients' logistics systems, and the impact of their contribution on logistics performance. This research aims therefore to provide further and better understanding of third party logistics, and to develop a general framework for evaluating the effects of the logistics competence and entrepreneurial behaviour (with regards to their clients' logistics requirements) of TPLPs on logistics outsourcing, and thus the strategic role assumed by TPLPs. At a scholarly level the prevailing contribution of this research is to create further understanding of the TPL phenomenon by examining it from a new perspective. On a practitioner or managerial level this research adds knowledge about the strategic significance of logistics outsourcing, which is directed at shippers and TPLPs. Existing categories of Third Party Logistics providers could be identified according to different degrees of TPL involvement (or logistics outsourcing). Furthermore a positive relationship between TPL resources and skills and TPL proactive behaviour was empirically verified. It was also found that the degree to which TPL providers are involved in their clients logistics systems is in positive relationships with logistics performance.Item Open Access Time-dependant road pricing: Modelling and evaluation(Cranfield University, 1995-09) Abd EL-Maksoad, Adel S. A.; Black, Ian G.Road pricing has an established history in the literature of transport economics, and its use as a theoretical and practical means of traffic restraint and management has attracted considerable interest for more than half a century. The theory of road pricing asserts that the optimal price should be the one that reflects the full cost of making an additional trip. Evidently, the magnitude of such a congestion toll varies over time and space. However, a review of some practical applications of road pricing in different countries reveals that no policy has as yet been implemented which aims to charge road users directly in relation to the congestion they actually cause and the time delay they impose on others. Therefore, the aim of this study is to model such a time-varying pricing scheme,t en-ned:T ime-DependentR oad Pricing, TDRP, and evaluate its various impacts on a single bottleneck as well as a traffic network. The TDRP function is derived basedo n the solution of the time-dependentq ueuesa nd delays problem at traffic junctions. The derived function is demonstrated to lead to a very unstable user equilibrium for a single bottleneck. Therefore, two different approaches are adopted to modifý this function: first, by considering the schedule delay changes imposed by vehicles on one another; and second, by using the day-to-day adjustment process. The former approach is demonstrated to eliminate queues completely and thus lead to system optimal SO for a single traffic bottleneck. Besides, the simulation solution demonstrates that TDRP, modified by the second approach, could lead to a stable equilibrium, and although it does not lead to SO it results in a very substantial reduction in queuing delay and travel time. To evaluate the stability of the results and the different impacts of TDRP on a traffic network, a traffic assigrunent model is developed. This model embraces route choices, departure time choices and the TDRP function, and it has the ability to evaluate the road network under different charging systems. Before evaluating the different impacts of TDRP on a traffic network, the importance of the phenomenon of interaction between nodes and its impacts on the value of TDRP are discussed. A general solution under specific traffic conditions as well as different TDRP scenarios are suggested. A set of numerical simulation experiments using the assignment model and a typical traffic network for urban areas is conducted. The results demonstrate that although TDRP does not eliminate the queues completely, it leads to a very substantial saving in travel time and queuing delay for all movements throughout the network under different levels of congestion. On the other hand, exempting some nodes (or links) from tile charges, would lead to a very substantial fall in the benefit obtained. The comparative analysis demonstrates that 7, DRP is a superioi charging system compared with other charging systems. It Is also concluded that TDRP docý' not represent the optimal charging system for a traffic network sliicc otlict cliirt-nin, nictliods could lead to a better performance under very high levels of charge Finally, the sensitivity of the results to work start time flexibility and the shadoN%va lues of the schedule delay function is investigated, and at the end, directions for further research arc proposed.