Tight Curves Research Articles

The Sydney to Brisbane Railway: Yesterday, Today and Tomorrow

The paper outlines the development of the Sydney to Brisbane “coastal” railway, which includes the Sydney to Maitland section completed in 1889; the linking up of branch lines between Maitland and Kyogle by 1923; and the completion of the Kyogle to South Brisbane section in 1930. Comment is given on the present state of the Sydney to Brisbane railway (which has 40% of its length on tight radius curves) and the ongoing upgrading of the Pacific Highway, along with a decline in rail’s modal share of corridor freight from about 24% in 1996 to less than 12% today. In addition to the track upgrading due to be completed by 2010 by the Australian Rail Track Corporation, the paper recommends not only upgrading the present Strathfield to Hexham section, but also consideration of rail deviations north of Hexham. The resulting improvement in rail freight efficiency and competitiveness from construction of a “fit for purpose” Sydney to Brisbane railway could give rail a 50% share of line haul freight. Compared with a projected 5% share by 2014, this upgrade would save 52 ML/a of diesel, as well as reduce greenhouse gas emissions and reduce external costs by over $90 million per annum. A major track upgrade would also allow for faster passenger train services and improve road safety.

3303 独立回転輪軸の縦クリープ力が車両運動に及ぼす影響(OS4-1:接触問題,OS4:接触問題とトライボロジ,オーガナイズド・セッション(OS),第18回交通・物流部門大会(TRANSLOG2009))

In this investigation, dynamic characteristics of independently rotating wheel systems (IRW) are discussed. To this end, a multibody IRW model is developed using the method of velocity transformation. The linear stability analysis of a two-axle IRW truck is first performed, and the hunting stability and vibration characteristics of IRW truck are investigated and the results are compared with those obtained using the multibody dynamics model. It is presented that the longitudinal creep force is not ideally equal to zero in tight curve negotiation and special care need to be exercised when a simplified IRW model developed by specifying zero longitudinal creepages is used.

Design and construction of Bukit Panjang LRT, Singapore

The Bukit Panjang light rapid transit (LRT) system, a groundbreaking project for the Land Transport Authority of Singapore, was designed to serve as a feeder to the existing mass rapid transit network and the Bukit Panjang bus interchange. The main civil engineering elements consist of 7·8 km of twin-track elevated guideway, 14 stations and a maintenance depot with an operation control centre. The system was completed and opened to the public in November 1999. This paper discusses the design and construction of the LRT guideway, which consists mainly of precast prestressed concrete segmental box girder bridges with epoxy glued joints and internally prestressed tendons. The bridge decks are predominantly simply supported spans ranging from15 to 34 m; however, a few special decks are made continuous due to stability requirements. Two overhead launching girders were employed for erecting the guideway. Due to specific site constraints and system requirements, the alignment was characterised by numerous tight curves with a minimum horizontal radius of 60 m. The geometry control method and construction equipment, such as the casting cells and the launching girders, were tailor-made in order to tackle the unconventional situation. Some operation and maintenance aspects of the system are also covered in this paper.

1211 マルチボディ・ダイナミクスを用いたLRV用セミアクティブ操舵台車の検討(SS9,OS9-1:ショットガンセッション,OS9/SS9:ショットガンセッション,オーガナイズド・セッション(OS),第18回交通・物流部門大会(TRANSLOG2009))

It is necessary for Light Rail Vehicle (LRV) to run on sharp curves smoothly. When LRV pass the tight curve, increase of the lateral force becomes serious problem. In the previous research, active control bogie with arranged linkage mechanism has been proposed and it enables the bogie to realize ideal curving. Active steering control requires sensors, actuators and other electronic devices. Therefore, it tends to become complex structure. In this paper, the newly proposed steering bogie with simple mechanism with semi-active damper is studied.

Simulation of curving at low speed under high traction for passive steering hauling locomotives

The traction control in modern electric and diesel electric locomotives has allowed rail operators to utilise high traction adhesion levels without undue risk of damage from uncontrolled wheel spin. At the same time, some locomotive manufacturers have developed passive steering locomotive bogies to reduce wheel rail wear and further improve locomotive adhesion performance on curves. High locomotive traction loads in curving are known to cause the loss of steering performance in passive steering bogies. At present there are few publications on the curving performance of locomotive steering with linkage bogies. The most extreme traction curving cases of low speed and high adhesion for hauling locomotives have not been fully investigated, with effects of coupler forces and cant excess being generally ignored. This paper presents a simulation study for three axle bogie locomotives in pusher and pulling train positions on tight curves. The simulation study uses moderate and high traction adhesion levels of 16.6% and 37% for various rail friction conditions. Curving performance is assessed, showing forced steering bogies to have considerable advantages over self steering bogies. Likewise it is shown that self steering bogies are significantly better than yaw relaxation bogies at improving steering under traction. As the required traction adhesion approaches the rail friction coefficient, steering performance of all bogies degrades and yaw of the bogie frame relative to the track increases. Operation with excess cant and tensile coupler forces are both found to be detrimental to the wear performance of all locomotive bogies, increasing the bogie frame yaw angles. Bogie frame pitching is also found to have significant effect on steering, causing increased performance differences between bogie designs.

Experimental tests and numerical simulations of railway vehicles at low speed in derailment conditions

This article is dedicated to the derailment phenomena, applied to two real cases in sharp curves. The multibody method is used to simulate the dynamic of two types of trains in the VOCOLIN environment. The first vehicle concerned is a metro passing in a turnout located between two tight curves. Only simulations are exposed, the semi-Hertzian method is used to describe the turnout. The second one is a special industrial vehicle with four wheelset bogies passing in a tight curve. In this case the contact is modelled by a multi-Hertzian method. The L/V ratio is calculated by simulations, measured by tests and compared with Nadal's criterion. The vertical force V is measured indirectly by deflections of the primary suspensions which stiffnesses are known. The lateral force L is estimated by a new method, the deflection of the wheelset.

Problems for a Modal Epistemology

I drive a little too fast when coming home from work. As I am about to drive through a particularly tight curve, often an image comes before my mind's eye of a bicyclist just beyond the bend. To avoid the possibility of a collision, I slow down. Other times, as I am looking in my rear view mirror, an image of a police car's flashing blue lights comes to mind. This image immediately causes me to take my foot off the gas to avoid the possibility of a speeding ticket. Here are two everyday examples of my using conceivability as a guide to possibility. Because I assume that these images provide me with a guide to possibility, I decelerate. But why think conceivability can provide me with such a guide? That is, why think that my conceiving of a certain state of affairs shows (or even provides prima facie evidence) that that state of affairs is possible?'1

Wheel/rail friction control with feedback system detecting yaw moment of wheelset

In the subway lines of Tokyo Metro, there are many tight curves that may cause squeal noise, excessive rail/wheel wear and also rail corrugation. To solve these serious problems, an onboard friction control system has been developed by the authors and has been equipped on some commercial trains [Y. Suda, H. Komine, T. Iwasa, M. Tomeoka, K. Matsumoto, N. Ubukata, M. Tanimoto, M. Nakata, and T. Nakai, Improvement of curving performance with friction control between wheel and rail, The 17th IAVSD Symposium Poster Session, Lyngby, Denmark, August, 2001; Y. Suda, H. Komine, T. Iwasa, T. Fujii, Tomeoka, K. Matsumoto, N. Ubukata, M. Tanimoto, M. Nakata, and T. Nakai, Experiment and analysis for improvement of curving performance with friction control between wheel and rail, Veh. Syst. Dynam. 41(Suppl.) (2004), pp. 507–516.]. With the system, in order to obtain the enough effect of friction control steadily, it is natural that an appropriate quantity of friction modifier should be required [K. Matsumoto, Y. Suda, T. Fujii, H. Komine, M. Tomeoka, Y. Sato, T. Nakai, M. Tanimoto, and Y. Kishimoto, The optimum design of an onboard friction control system between wheel and rail in a railway system for improved curving negotiation, Veh. Syst. Dynam. 44(Suppl.) (2006), pp. 531–540]. On such a viewpoint, the authors propose a new friction control system with the detection of yaw moment acting on the running wheelset. In this paper, first, outline of conventional feed-forward control system is introduced; secondly, the concept of feedback friction control system is presented considering the results of the multi-body dynamics simulations, and finally some field running test results of the developed system are discussed.

Seizure and wear rate testing of wheel–rail contacts under lubricated conditions using pin-on-disc methodology

An increased wear rate and a shift of wear mechanism in the wheel–rail contact has been observed in tight curves, mainly due to the change from an almost pure rolling contact to more of a sliding contact. The wheel flange–rail gauge contact is commonly known to experience the toughest conditions of the overall wheel–rail contact in terms of contact pressure and sliding velocity. The wheel flange–rail gauge contact is preferably lubricated to reduce the wear rate and to minimise the risk of transition to severe wear or seizure. The amount and type of lubrication are therefore important parameters if one is to control the wear rate. In this study, a flange contact is experimentally simulated using pin-on-disc testing, to determine the difference in wear rate among a selection of lubricants under different contact conditions. The selection of lubricants consisted of environmentally adapted oils, mineral oils, and greases containing different amounts of EP and AW additives. The results of the pin-on-disc testing indicate that both the amount and type of lubrication applied is decisive for the wear rate and active wear mechanism. Tests have also been performed to simulate either on-board or wayside lubrication, by applying the lubricant at different intervals. A general observation is that under starved lubrication conditions a transition to severe wear is initiated and the wear rate increases rapidly, i.e., all tests indicate that the contact between wheel and rail must be lubricated to avoid high wear rates.

Design and construction of Bukit Panjang LRT, Singapore

The Bukit Panjang light rapid transit (LRT) system, a groundbreaking project for the Land Transport Authority of Singapore, was designed to serve as a feeder to the existing mass rapid transit network and the Bukit Panjang bus interchange. The main civil engineering elements consist of 7·8 km of twin-track elevated guideway, 14 stations and a maintenance depot with an operation control centre. The system was completed and opened to the public in November 1999. This paper discusses the design and construction of the LRT guideway, which consists mainly of precast prestressed concrete segmental box girder bridges with epoxy glued joints and internally prestressed tendons. The bridge decks are predominantly simply supported spans ranging from 15 to 34 m; however, a few special decks are made continuous due to stability requirements. Two overhead launching girders were employed for erecting the guideway. Due to specific site constraints and system requirements, the alignment was characterised by numerous tight curves with a minimum horizontal radius of 60 m. The geometry control method and construction equipment, such as the casting cells and the launching girders, were tailor-made in order to tackle the unconventional situation. Some operation and maintenance aspects of the system are also covered in this paper.

Contrasting rainfall generated debris flows from adjacent watersheds at Forest Falls, southern California, USA

Debris flows are widespread and common in many steeply sloping areas of southern California. The San Bernardino Mountains community of Forest Falls is probably subject to the most frequently documented debris flows in southern California. Debris flows at Forest Falls are generated during short-duration high-intensity rains that mobilize surface material. Except for debris flows on two consecutive days in November 1965, all the documented historic debris flows have occurred during high-intensity summer rainfall, locally referred to as ‘monsoon’ or ‘cloudburst’ rains. Velocities of the moving debris range from about 5 km/h to about 90 km/h. Velocity of a moving flow appears to be essentially a function of the water content of the flow. Low velocity debris flows are characterized by steep snouts that, when stopped, have only small amounts of water draining from the flow. In marked contrast are high-velocity debris flows whose deposits more resemble fluvial deposits. In the Forest Falls area two adjacent drainage basins, Snow Creek and Rattlesnake Creek, have considerably different histories of debris flows. Snow Creek basin, with an area about three times as large as Rattlesnake Creek basin, has a well developed debris flow channel with broad levees. Most of the debris flows in Snow Creek have greater water content and attain higher velocities than those of Rattlesnake Creek. Most debris flows are in relative equilibrium with the geometry of the channel morphology. Exceptionally high-velocity flows, however, overshoot the channel walls at particularly tight channel curves. After overshooting the channel, the flows degrade the adjacent levee surface and remove trees and structures in the immediate path, before spreading out with decreasing velocity. As the velocity decreases the clasts in the debris flows pulverize the up-slope side of the trees and often imbed clasts in them. Debris flows in Rattlesnake Creek are relatively slow moving and commonly stop in the channel. After the channel is blocked, subsequent debris flows cut a new channel upstream from the blockage that results in the deposition of new debris-flow deposits on the lower part of the fan. Shifting the location of debris flows on the Rattlesnake Creek fan tends to prevent trees from becoming mature. Dense growths of conifer seedlings sprout in the spring on the late summer debris flow deposits. This repeated process results in stands of even-aged trees whose age records the age of the debris flows.

Idealized steering for hauling locomotives

Most of the passive and active steering developments of traction bogies have been directed towards high speed rail or light rail and commuter rail applications. Previous studies ignored coupler forces and often assumed the wheel rail profiles have ample conicity for the curving task. There is little work directed towards high adhesion rates which is a critical area for freight locomotive performance. In heavy haul train operations ruling grades are often associated with tight curvatures, and steering tasks of hauling locomotives are affected by lateral components of longitudinal train forces. Haul locomotives also have a significant yaw moment from coupler forces making uneven longitudinal creeps useful in balancing these yaw forces. The use of larger diameter wheels on locomotives reduces effective steering conicity such that contact profiles may become insufficient to negotiate tight curves. The large diameter wheels make longitudinal creepage or slip inevitable and Goodall et al. [1] definition of perfect steering unattainable. A new criteria for ideal steering in these conditions is proposed. For hauling locomotives, ideal steering is defined as when the lateral rail creep and contact loads of each axle in one bogie are equal and longitudinal creeps are positive to the applied traction. This definition is applicable to all curving tasks that a hauling locomotive encounters while still applying low wheel rail creep forces. In most of the cases ideal steering can be achieved with zero lateral creep forces. The paper describes equations for quasi-static curving forces including traction and in-train forces. An analysis of curving forces for locomotives with three axle bogies is made with the equations for various curvatures and with haulage locomotives in different train configurations including pusher configuration.

Cardiology Is Flow

Panta rhei. (Everything flows).1 Cardiology is about flow. The primary purpose of the cardiovascular system is to drive, control, and maintain blood flow to all parts of the body. Flow dictates the form and function of the heart and blood vessels through ontogenic and phylogenic development, the structural and functional consequence of repair, and in its end stages, remodeling and response to failure. Flow should therefore be a primary focus by which we explain where lesions form, why they degrade and decompensate, and how we grade the extent of restoration of function after vascular intervention. Yet this is not the case. Flow is not a standard part of our clinical lexicon. Few reliable and consistent means of measuring flow exist. Despite early use of surrogate flow markers (eg, TIMI frame count), we do not quantify flow restoration after interventions. Moreover, there is simply no agreement as to the aspect or degree of flow that is most important in lesion development or functional recovery. Article p 2744 The nonhomogeneous nature of atherosclerosis has been appreciated since the earliest days of research in the field.2 Certain arterial segments develop profound lesions, whereas adjacent regions seem completely spared. Neither properties of blood nor local cellular and molecular biological events can vary significantly on such length scales to explain such spatial heterogeneity. Local flow properties can change on these scales (Figure 1), and alterations in local flow pattern—for example, the intricate vectorial description of fluid speed and direction across the entire cross section of the lumen—were invoked as a possible explanation for the observed scatter in pathology.2–5 In this context, lesion distribution is not random but aligns with, and accumulates within, areas of flow disturbances such as those that occur around tight curves, bifurcations, and in areas already beset by atherosclerosis. …

Evaluating the Safety Risk of Narrow Medians Using Reliability Analysis

In British Columbia, many highways are located in mountainous terrain and the costs of highway construction in these areas are high. One method of controlling construction costs is narrow medians but the safety consequences of using narrow medians were never determined. Recent research on safety in geometric design has focused on establishing quantitative relationships between collisions and cross-sectional elements using collision prediction models (CPMs) and collision modification factors (CMFs). In some situations, such as the use of narrow medians, it is difficult to find CPMs and CMFs that adequately describe the design scenario. In other instances, it is difficult to measure the safety in terms of collision reduction because of a lack of data or difficulty isolating the impact of a single design element on collision frequency. In these situations, reliability analysis can be used to evaluate the risk associated with a particular design feature. Reliability analysis is not intended as an alternative to quantify safety using collision frequency but represents a complementary method of measuring safety in terms of risk. In this paper, reliability analysis was completed on a series of horizontal curves with varying horizontal sight distance restrictions and the probability of being unable to stop within the available sight distance was calculated. The results of the study found that narrow medians combined with tight horizontal curves did not provide sufficient sight distance that vehicles would be expected to stop if an object was in a vehicle's path. The analysis was applied to a case study of two constrained alignments in mountainous terrain of British Columbia.

An investigation into the influence of longitudinal creepage on railway squeal noise due to lateral creepage

Curve squeal noise is of growing concern for the railway industry as rail systems become more widespread in densely populated areas. In response to the pressure to minimise environmental pollution, there is a demand for a deeper understanding of the phenomenon and to develop a methodical approach to managing the wheel–rail system. Under curving, the wheel and the rail are subject to creep forces due to relative motion (creepage) within the contact region. In tight curves, these creep forces can cause unstable vibration of the wheel, leading to the radiation of squeal noise. The occurrence and characteristics of this are governed by the configuration of the creepages at the wheel–rail contact, which can have longitudinal, lateral and spin components. It follows that the representation of creepage is important in modelling the mechanisms of squeal noise behaviour. An investigation is presented into how the relationship between lateral creepage and creep force is affected when a component of longitudinal creepage is introduced. A 1:3 scale laboratory test rig has been modified to simulate contact conditions with controlled levels of lateral and longitudinal creepage, and to measure the salient system parameters. The experimental results are presented and discussed here.

The optimum design of an onboard friction control system between wheel and rail in a railway system for improved curving negotiation

In the subway lines of Tokyo (Tokyo Metro), there are many tight curves that may cause squeal noise, excessive rail/wheel wear and rail corrugation. To solve these serious problems, an onboard friction control system with friction modifier has been developed by the authors and has been equipped on commercial trains as a trial. With this system, the balance between supply and consumption of friction modifier is very important. That is to say, in order to obtain the maximum effect of friction control steadily, it is natural that an appropriate quantity of friction modifier should be required. In this report, results of experiments with a two-roller-rig testing machine, and analysis of the observed data in commercial train tests are introduced. In addition, the authors considered the method to realize the appropriate balance between supply and consumption of friction modifier.

2405 車輪/レール間摩擦制御時の曲線通過シミュレーション(OS9 接触問題とトライボロジ,OS9 接触問題とトライボロジ,TRANSLOG 2006)

In the subway lines of Tokyo Metro, there are so many tight curves that may cause squeak noise, excessive wheel/rail wear and also rail corrugation. To solve these serious problems, onboard friction control system with friction modifier has been developed by authors and has been equipped on commercial trains as a trial. With the system, the balance between supply and consumption of friction modifier is very important for the system design. That is to say, in order to obtain the enough effect of friction control steadily, it is natural that appropriate quantity of friction modifier should be required. In this paper, results of numerical analysis with multi-body dynamics (MBD) software, A'GEM, and analysis with the result of test run with commercial train are reported. And with the results authors show the possibility to realize the feedback control of spraying friction modifier with the detection of the load acts on mono-link of the bogie truck.

Running performance of power-steering railway bogie with independently rotating wheels

This article proposes the concept of a steering bogie which utilizes self-steering ability while realizing further running performance with slight active control on a tight curve. An independently rotating wheel with EEF bogie naturally has self-steering ability, making use of gravity stiffness aroused by nonlinear tread gradient, but has oscillation in the wheel-steering motion. The proposed power-steering railway bogie consists of independently rotating wheels with a power-steering device and enables us to eliminate steering vibration while realizing ideal steering with slight power assist on curving. In this article, the theoretical investigation of the power-steering bogie and the control strategies is mentioned. Experimental results and numerical simulations with a scaled model vehicle show the effectiveness of the proposed bogie design and the proposed power-steering control.

The start of phonotactic walking in the flyOrmia ochracea: a kinematic study

Ormia ochracea (Diptera, Tachinidae) are acoustic parasitoids of crickets that have one of the most directionally sensitive auditory systems known. We studied dynamic characteristics of walking phonotaxis in these flies in response to variations in sound source azimuth, and compared phonotaxis of flies in freely walking conditions to tethered flies walking on a treadmill. Motor patterns at the initiation of phonotaxis are not stereotyped even for similar stimulus conditions. Flies respond to directional sound sources by walking in a tight curve that combines rotation and forward translation until they are oriented towards the source direction, then continue on a straight path. Translational velocity accelerates throughout the duration of the stimulus then decelerates following stimulus offset. In contrast, rotational velocity accelerates and then decelerates within the duration of the stimulus such that flies have completed the rotational component of the response and reached their final heading before the end of the stimulus. Rotational velocity is the only response parameter that varies systematically with sound source direction (azimuth). Differences in the amplitude of rotational velocity as a function of source azimuth determine the directional orientation of phonotactic responses. The relationship between rotational velocity and source azimuth is similar to a neural measure of auditory directionality (interaural latency). There were some differences between freely walking and tethered conditions, although both showed qualitatively similar responses. Flies accelerated more slowly and attained lower maximum velocities on the treadmill, consistent with the greater inertia of the treadmill sphere relative to the flies. Also, flies tended to continue walking longer on the treadmill following cessation of the stimulus.

Position-Detecting System Based on the Global Positioning System

The Railway Technical Research Institute has developed a position detection system based on a new Global Positioning System (GPS). This system uses GPS to detect the approximate location of a train and then selects one of three algorithms to process the location data and determine the train's precise location. Running tests performed on the system showed that its position error was less than 4 m. This system has the potential to be used to control the car body tilting of tilt trains accurately and allow them to run at the maximum possible speed through the tight curves typical of the narrow-gage lines found in Japan. In addition, the automatic map created by this system makes it much easier to maintain the accuracy of the onboard database.