Distributed support modelling for vertical track dynamic analysis

The finite length nature of rail-pad supports is characterised by a Timoshenko beam element formulation over an elastic foundation, giving rise to the distributed support element. The new element is integrated into a vertical track model, which is solved in frequency and time domain. The developed formulation is obtained by solving the governing equations of a Timoshenko beam for this particular case. The interaction between sleeper and rail via the elastic connection is considered in an analytical, compact and efficient way. The modelling technique results in realistic amplitudes of the ‘pinned–pinned’ vibration mode and, additionally, it leads to a smooth evolution of the contact force temporal response and to reduced amplitudes of the rail vertical oscillation, as compared to the results from concentrated support models. Simulations are performed for both parametric and sinusoidal roughness excitation. The model of support proposed here is compared with a previous finite length model developed by other authors, coming to the conclusion that the proposed model gives accurate results at a reduced computational cost.     

Attitudes of bus operators towards real-time transit information tools

Although it is apparent that providing useful information has a positive effect on transit riders, no studies to date have investigated bus operators’ reactions to real-time arrival information and other potential rider information tools. In this study, the project team surveyed 253 bus operators to determine their views and values concerning the existing use of real-time information and to ask about future transit rider information applications. Almost all operators (93 and 91 % on two separate questions) were positive or neutral to the provision of real-time information. In addition, operators were receptive to building other new information applications, with all applications in the survey being supported by at least 60 % of the bus operators. The two most widely supported potential applications in the survey were additional tools to help blind and deaf-blind riders (89 % of bus operators favored) and an application that would aid riders in identifying physical stop, shelter and bus issues such as graffiti, broken parts or a need for lights (88 % of bus operators). Applications displaying data about past performance or current bus capacity received the least support (66 and 61 % respectively). This research gives a better understanding of the impact of rider information tools on bus operators, including the views and values of the operators, and the harms and benefits of such tools.     

Mathematical relationships among parking characteristics and revising and reduction methods of parking field survey information

Several characteristics are defined to describe parking. The mathematical relationships between these characteristics are derived both in a general form and applied to specified parking duration distribution. The results of the analysis can be applied in planning and dimensioning of parking places. Methods of revising and generalizing field survey data collected by periodic check methods are discussed. A method for the reduction of number of observations in parking studies is presented. Three examples are given to illustrate the use of the mathematical methods.     

挪威新型摆式列车

介绍了挪威新型摆式列车，该列车的运行可缩短旅行时间，提高乘车舒适度，并可增加铁路的竞争力。     

Non-Linear Behavior of a Rubber Isolator System Using Fractional Derivatives

A non-linear rubber isolator included in a dynamic system is examined where influences of dynamic amplitude and frequency are investigated through measurements and modeling. The frequency dependence of the isolator is modeled by a fractional calculus element while a frictional component accounts for its amplitude dependence. The model works in the time-domain and simulations of harmonic and non-harmonic motion are compared to measurements. Good agreement is obtained in a wide frequency and amplitude range for a freely oscillating one degree of freedom system, with the isolator acting as a coupling between exciting foundation and mass, and for a single isolator showing the typical amplitude dependence known as the Payne effect. The model is found to be superior to the commonly applied Kelvin-Voigt element in modeling the dynamic isolator properties.     

Where Is My Bus? Impact of mobile real-time information on the perceived and actual wait time of transit riders

In order to attract more choice riders, transit service must not only have a high level of service in terms of frequency and travel time but also must be reliable. Although transit agencies continuously work to improve on-time performance, such efforts often come at a substantial cost. One inexpensive way to combat the perception of unreliability from the user perspective is real-time transit information. The OneBusAway transit traveler information system provides real-time next bus countdown information for riders of King County Metro via website, telephone, text-messaging, and smart phone applications. Although previous studies have looked at traveler response to real-time information, few have addressed real-time information via devices other than public display signs. For this study, researchers observed riders arriving at Seattle-area bus stops to measure their wait time while asking a series of questions, including how long they perceived that they had waited.The study found that for riders without real-time information, perceived wait time is greater than measured wait time. However, riders using real-time information do not perceive their wait time to be longer than their measured wait time. This is substantiated by the typical wait times that riders report. Real-time information users say that their average wait time is 7.5 min versus 9.9 min for those using traditional arrival information, a difference of about 30%. A model to predict the perceived wait time of bus riders was developed, with significant variables that include the measured wait time, an indicator variable for real-time information, an indicator variable for PM peak period, the bus frequency in buses per hour, and a self-reported typical aggravation level. The addition of real-time information decreases the perceived wait time by 0.7 min (about 13%).A critical finding of the study is that mobile real-time information reduces not only the perceived wait time, but also the actual wait time experienced by customers. Real-time information users in the study wait almost 2 min less than those arriving using traditional schedule information. Mobile real-time information has the ability to improve the experience of transit riders by making the information available to them before they reach the stop.     

On the dynamics of oxygen,phosphorus and cyanobacteria in the Baltic Sea; A model study

Oxygen and phosphorus dynamics and cyanobacterial blooms in the Baltic Sea are discussed using results from the Swedish Coastal and Ocean Biogeochemical model (SCOBI) coupled to the Rossby Centre Ocean model (RCO). The high-resolution circulation model is used to simulate the time period from 1902 to 1998 using reconstructed physical forcing and climatological nutrient loads of the late 20th century. The analysis of the results covers the last 30 years of the simulation period. The results emphasize the importance of internal phosphorus and oxygen dynamics, the variability of physical conditions and the natural long-term variability of phosphorus supplies from land on the phosphorus content in the Baltic Sea. These mechanisms play an important role on the variability of available surface layer phosphorus in late winter in the Baltic Sea. The content of cyanobacteria increases with the availability of phosphorus in the surface layers of the Baltic proper and the probability for large cyanobacteria blooms in the model is rapidly increased at higher concentrations of excess dissolved inorganic phosphorus in late winter. The natural increase of phosphorus supplies from land due to increased river runoff since the early 1970s may to a large degree explain the increased phosphorus content in the Baltic proper. Another significant fraction of the increase is explained by the release of phosphorus from increased anoxic areas during the period. These results refer to the long-term variability of the phosphorus cycle. In accordance to earlier publications is the short-term (i.e. interannual) variability of the phosphorus content in the Baltic proper mainly explained by oxygen dependent sediment fluxes.