This paper describes the methodology for safety assessment related to the risk of a train overturning in strong cross-winds. As an example, this methodology is applied on the high-speed line Botniabanan being built for a maximum speed of 250 km/h in the northeast coastal region of Sweden. The process starts with a systematic identification of locations along the line having a potential high risk of overturning due to cross-winds. This is followed by a cross-disciplinary study. The first step is to estimate the probabilities of wind velocity and wind directions. The next step is aerodynamic computation of overturning forces and moments acting on relevant types of train. Further, the critical overturning wind velocity is determined by a multi-body simulation technique. Finally, the overturning accident frequency is calculated. The calculated risk is compared with generally accepted risk levels in modern train operation.

Increased speeds of trains can be achieved by using tilting trains that decrease the lateral acceleration experienced by passengers on curves, thereby allowing trains to run typically 25-30% faster on existing curved track and maintaining good ride comfort. Unfortunately, motion sickness in tilting trains is a major problem for some passengers. To investigate the incidence of motion sickness and the extent to which different tilt compensation strategies influence its occurrence, tests were conducted with a tilting train on a track with a large number of curves. Eighty healthy volunteers were studied, selected partly for their susceptibility. Three different cars were evaluated during 3 test days, with each test ride lasting about 3 h. On four occasions per test ride, the subjects answered a questionnaire concerning activities during the ride, ride comfort, ability to work and read, vegetative symptoms, fatigue, sleepiness, nausea and well-being. Subjects estimation of average ride comfort and ability to work and read was good in all conditions. However, 10% of the test subjects reported various symptoms of motion sickness (SMS). A 55% degree of tilt compensation of the lateral acceleration instead of the normal 70% reduced the symptoms of motion sickness incidence (SMSI) by 25-40%. SMSI correlated poorly with motion doses, which integrates vertical or lateral acceleration but correlated well with roll acceleration motion dose (r2 = 0.43, p < 0.001). For women, riding backward (p < 0.001) minimized SMSI, but men were insensitive to direction. Future railway design will have to optimize tilt systems by both minimizing motion sickness and avoiding excessive lateral acceleration or jerk.

Summary 1.Freshwater fish are a potentially important link in the transfer of radionuclides from polluted ecosystems to people. A pulsed contamination event such as the Chernobyl fallout in 1986 is a challenge to the prediction of radioactivity in biota, because activity concentrations of radionuclides can change dynamically among populations during an initial equilibration phase. This was demonstrated from time-series of 137 caesium (Cs) in fish from three Swedish lakes (1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000), eight species, > 7600 individuals). In addition, we used these data to test hypotheses about the influence of fish size and trophic level on the temporal patterns of 137 Cs. 2. In order to facilitate comparisons, a pulse-response model was developed to extract key parameters from field data: the timing ( t max ) and level ( Cs max ) of the peak concentrations, the near steady-state level ( Cs base ) and the long-term decline rate ( λ ). 3. Peak concentrations in different fish were attained 56 -806 days after the fallout. This delay ( t max ) increased with body size and trophic level. Cs max increased with fish size but was highest at intermediate trophic levels. Cs base increased by a factor of 1·8 per trophic level, but was not influenced by size across species. The 137 Cs-size relationship within species, however, shifted from negative to positive during the first 2 years. 4. The apparent ecological half-life ( T 1/2 ) for 137 Cs increased after t max and initially differed among fish and lakes. About 10 years after the fallout T 1/2 was no longer significantly different among fish or lakes, suggesting that steady-state among 137 Cs levels in fish had been reached. The mean T 1/2 during 1996-2000 was 46 years, implying that the future recovery from present 137 Cs levels (more than 10-fold higher than preChernobyl levels) will be dominated by the physical decay of 137 Cs (30 years). 5. The influence of fish size and trophic level on 137 Cs dynamics has been consistent among the three lakes. The duration of the 137 Cs pulse in fish appeared to be regulated by fish ecophysiology, whereas the amplitude also appeared to be regulated by lake characteristics. 6. Synthesis and applications. These data have implications for the predictive modelling of pulsed contaminants in lake ecosystems and show that (i) complex temporal concentration trends in fish can be adequately modelled by a combination of simple firstorder equations; (ii) a one-component decline function is insufficient to describe the observed increase in ecological half-life over time; (iii) fish weight and trophic level can and should be treated as independent variables because their influence differs and changes over time. For management purposes, a pulse-response model for fish can be scaled to different systems by using established relationships to account for differences in fallout and catchment biogeochemistry.

The cost of maintaining and renewing railway tracks affected by traffic-dependent deterioration is considerable. It is important not only to have proper maintenance regimes, but also to have knowledge of the interaction between vehicles and track in order to reduce the deterioration of both.In a joint project between Banverket (Swedish Rail Administration) and KTH (Royal Institute of Technology, Stockholm), a model for track deterioration is developed, considering track settlement, component fatigue, abrasive wear, and rolling contact fatigue of rails. The basis of the model is taken from what is considered as state-of-the-art knowledge. The model is used as a basis for a proposed new track access charging regime for Banverket, able to differ between vehicle types based on their characteristics and tendency to deteriorate the tracks.The model is implemented in an Excel ® environment and applied to Swedish mainline traffic and vehicles. Using representative vehicle characteristics in determining track deterioration, it is predicted that there are large differences between different vehicles regarding their deterioration of the tracks. The model predicts axle load, unsprung mass, and wheelset steering capability as decisive for track deterioration. The model is believed to predict realistic results also for heavyhaul rail operations.

This paper initially describes the main features of the radial selfsteering bogies, which have been developed for the high speed train X2000. suburban trains and other applications. One of the main goals with these bogies is to reduce lateral track forces at high speed curving.This development has been supported by extensive theoretical investigations parallel to practical tests and verifications. Since around 1973 the main tool for theoretical analysis has been time domain simulations of non-linear vehicle-track models under influence of perfect and irregular track geometry. There are models for verticaVlongitudinal and for lateral dynamics. The models are assembled and utilised in a specialised computer program, SIMFO, and in a more general computer code, GENSYS, the latter having full 3-dimensional capability. A frequently used model for lateral dynamics of a four-axle bogie vehicle with 37 degrees of freedom (DOF) is shown as an example. In order to avoid an unrealistically stiff lateral coupling between wheel axles and ground, this model contains lateral track-ground elasticity and I or lateral and torsional DOF for each wheel. By comparison with measurements it is shown that characteristic quasistatic and dynamic behaviour can be simulated with accuracy.