A practical capacity model of a single track line

The paper presents a model for determining the practical capacity of a single track line, i.e. the maximum number of trains which can be run along it in a time unit under the condition that each train enters its bottleneck segment with a definite delay.

The input data used in the model are: geometrical characteristics of the bottleneck segment of the line under study, the intensity and structure of demand expressed by a number of trains which are run over the line in a given time unit, the scenario of traffic running over the line under study and the operational tactics of individual train categories processing on the bottleneck segment.

(Two tactics can be applied in the train processing on the line under study; first, the trains of individual categories are given different priorities in the processing, and second, all the trains have the same priority).

The output results of the model are average delays of trains of each category occurring within the train processing performed on the bottleneck segment of the line under study in a given time unit.     

Quantitative evaluation of passenger terminal orientation

When passenger terminal layout is being decided, one of the important aspects to consider is how the passenger orients himself during his visit to the terminal and his movements through it, i.e. terminal orientation. Among other things, this terminal characteristic results from visibility, or the visual connectivity between elements and spaces. The paper proposes an amendment and modification to the known method for the quantitative evaluation of terminal orientation which uses an oriented network to describe the connectivity of elements (terminal orientation). The amendment and modification of the method consists of proposing that during evaluation only visual connections that have functional meaning should be considered, rather than all visual connections. A further modification is the introduction of different weights for different connections. The example presented in the paper considers an airport terminal building.     

Goods transport in Etarea

Etarea is a planned satellite town for Prague, the capital of Czechoslovakia, located some 10 km from the outskirts of the capital. Its projected population of 135,000 will live in 13 residential areas, each of which will have its own retail centre in addition to the main retail centre.The plans for Etarea incorporate a unique approach to the related problems of the storage and distribution of goods within urban areas. All incoming goods will be delivered by road or rail, and possibly in the future by water, to a central storage complex. Goods for the retail trade are distributed from this central store by automated trains pulled by battery-powered trucks, each train having a capacity of 8.75 tons. The trains, which run in a network of underground tunnels, 2 \sX 2.5 meters in cross section, are guided by an optical sensing system. The underground network comprises 3 main routes with branches serving the individual centres. Secondary storage facilities are planned for each of the 14 retail centres where unit loads received from the main storage centre are subdivided for retail sale.One of the proposed methods of retail distribution provides for the fully automated delivery of goods from the retail centres direct to the consumer's household. This is accomplished by means of a pneumatic tube system similar to that used for handling cash in some large stores. Orders will be placed by dialling the code number assigned to the required item, given in a catalogue of available goods. Provided that the customer's account is in credit the order will be accepted and the goods automatically dispatched from the local centre; delivery is estimated to take between 2.5 and 11.5 minutes depending on the distance of the customer's house from the centre. The same system is utilised for the delivery of regular orders for such items as newspapers and magazines as well as for mail and for the the removal of household refuse. In addition to the automated system each retail centre will also have over-the-counter, self-service and slot machine facilities for the sale of goods.All proposals for goods storage and distribution planned for Etarea are based on existing technologies.     

Light Rail Rapid Transit systems for more sustainable ground accessibility of airports

This paper investigates the potential of Light Rail Rapid Transit (LRRT) to mitigate the environmental and social burden of ground access systems of an airport. This implies, on the one hand, LRRT's capability in mitigating externalities in terms of noise, air pollution/climate change, traffic incidents/accidents and congestion of airport ground access systems and, on the other, the provision of sufficient capacity to accommodate generally increasing volumes of both air passenger and airport employee demand by connecting the airport to its core catchment area. A methodology for assessing the capability of LRRT operating as an airport ground access system is developed. This methodology consists of models to analyze and predict demand and capacity for an LRRT system and models to quantify the externalities of particular airport ground access systems as well as assessing their prospective savings thanks to the introduction of an LRRT system. The methodology is applied to a large European airport – Amsterdam Schiphol (the Netherlands) – using a ‘what-if?’ scenario approach.     

Design and evaluation of a grade-separated intersection: a case study of the proposed Belgrade ‘Hipodrom’

This paper presents the evaluation results of three traffic solutions for the complex grade-separated intersection located in the old part of Belgrade at the junction with the new bridge over the Sava River. The corridor to which the intersection belongs together with the new river bridge are parts of a great urban artery called the Inner Half Semi-Ring Road (IHSRR). The traffic solutions that are evaluated are defined in the preliminary design phase, based on two opposed concepts: a complete grade separation of all intersection legs (the CPV alternative – ‘grade-separated’) and a grade separation designed to minimise construction costs (DMC 1 and 2 alternatives – ‘minimise cost’). The evaluation procedure is conducted in three steps: first, the score based on expert assessment of the functionality of the design solutions is determined; second, the alternatives are ranked according to the value of a set of state indicators obtained by micro-simulation using PTV–VISSIM 4.10; and third, the final score is obtained by multi-criteria evaluation using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method. The results of the first evaluation step show a small advantage for DMC 2, a sub-alternative of the DMC 1 alternative. The results of the micro-simulation give advantage to the DMC 1 alternative. The multi-criteria evaluation provides a better ‘goodness factor’ for the CPV alternative against the DMC 1 alternative. At the same time, the least construction cost favours alternative DMC 1.     

Competition for the German regional rail passenger market 5 years after regionalization

The paper investigates the competition for regional passenger rail services in Germany from 1996 to 2000 by using data mainly provided by regional authorities. It analyses data on the level of network characteristics, contract life, the Länder (i.e. regions), competitive placing procedures, and their winners as well as achieved cost and services improvements. It finds that with competition being rare, the amount of competitively placed services declined until recently. Only about half of the regional authorities gained experience with competitive placings, which points at the expertise deficit of these bodies. A diverse picture on competitive placings' characteristics such as network size and contract life appears. State-owned carrier DB AG remains the dominant player as it could win the majority of the competitively procured services. Private companies have played a minor role in the game up to now. Accomplished reduction of subsidies and improved service quality respectively provide an indication of the potential for enhancing efficiency in this market.     

A GIS‐based traffic analysis zone design: implementation and evaluation

The purpose of this paper is to implement an efficient method for GIS‐based traffic analysis zone (TAZ) design in order to evaluate and validate such a method. The method was developed by the authors.

Moran's I spatial autocorrelation coefficient and sample variance are used for evaluating the generated TAZs using the Champaign‐Urbana, IL region as a case study. Sensitivity analysis is also conducted to explore the fluctuations in TAZ generation outcomes. The evaluation, the validation as well as the TAZ design have been implemented with ARC/INFO GIS software on a UNIX workstation platform.     

Assigning fighter plane formations to enemy aircraft using fuzzy logic

Fighter aircraft protect specific facilities on alert in the air by patrolling expectation zones. These zones are located in the direction from which enemy aircraft attacks are expected; fighter formations are sent from them to intercept enemy aircraft. The problem considered in this paper is to determine the optimum assignment of fighter plane formations to enemy formations. The proposed solution is based on fuzzy logic and integer linear programming. A numerical example is given to illustrate the application possibilities of the proposed solution.     

Monolithic coupling of the pressure and rigid body motion equations in computational marine hydrodynamics

In Fluid Structure Interaction(FSI) problems encountered in marine hydrodynamics, the pressure field and the velocity of the rigid body are tightly coupled. This coupling is traditionally resolved in a partitioned manner by solving the rigid body motion equations once per nonlinear correction loop, updating the position of the body and solving the fluid flow equations in the new configuration. The partitioned approach requires a large number of nonlinear iteration loops per time–step. In order to enhance the coupling, a monolithic approach is proposed in Finite Volume(FV) framework,where the pressure equation and the rigid body motion equations are solved in a single linear system. The coupling is resolved by solving the rigid body motion equations once per linear solver iteration of the pressure equation, where updated pressure field is used to calculate new forces acting on the body, and by introducing the updated rigid body boundary velocity in to the pressure equation. In this paper the monolithic coupling is validated on a simple 2D heave decay case. Additionally, the method is compared to the traditional partitioned approach(i.e. "strongly coupled" approach) in terms of computational efficiency and accuracy. The comparison is performed on a seakeeping case in regular head waves, and it shows that the monolithic approach achieves similar accuracy with fewer nonlinear correctors per time–step. Hence, significant savings in computational time can be achieved while retaining the same level of accuracy.     

The influence of route choice and operating conditions on fuel consumption and CO<Subscript>2</Subscript> emission of ships

The influence of various parameters, such as ship initial speed (full ahead and lower engine loads), loading condition, heading angle and weather conditions on ship fuel consumption and CO₂ emission is presented. A reliable methodology for estimating the attainable ship speed, fuel consumption and CO₂ emission in different sea states is described. The speed loss is calculated by taking into account the engine and propeller performance in actual seas as well as the mass inertia of the ship. The attainable ship speed is obtained as time series. Correlation of speed loss with sea states allows predictions of propulsive performance in actual seas. If the computation is used for weather routing purposes, values for various ship initial speed, loading conditions and heading angles for each realistic sea‐state must be provided. The voluntary speed loss is taken into account. The influence of the ship speed loss on various parameters such as fuel consumption and CO₂ emissions is presented. To illustrate the presented concept, the ship speed and CO₂ emissions in various routes of the Atlantic Ocean are calculated using representative environmental design data for the track of the routes where the ship will sail.