Organic carbon budget for the Gulf of Bothnia

We calculated input of organic carbon to the unproductive, brackish water basin of the Gulf of Bothnia from rivers, point sources and the atmosphere. We also calculated the net exchange of organic carbon between the Gulf of Bothnia and the adjacent marine system, the Baltic Proper. We compared the input with sinks for organic carbon; permanent incorporation in sediments and mineralization and subsequent evasion of CO₂ to the atmosphere. The major fluxes were riverine input (1500 Gg C year^− 1), exchange with the Baltic Proper (depending on which of several possible DOC concentration differences between the basins that was used in the calculation, the flux varied between an outflow of 466 and an input of 950 Gg C year^− 1), sediment burial (1100 Gg C year^− 1) and evasion to the atmosphere (3610 Gg C year^− 1). The largest single net flux was the emission of CO₂ to the atmosphere, mainly caused by bacterial mineralization of organic carbon. Input and output did not match in our budget which we ascribe uncertainties in the calculation of the exchange of organic carbon between the Gulf of Bothnia and the Baltic Proper, and the fact that CO₂ emission, which in our calculation represented 1 year (2002) may have been overestimated in comparison with long-term means. We conclude that net heterotrophy of the Gulf of Bothnia was due to input of organic carbon from both the catchment and from the Baltic Proper and that the future degree of net heterotrophy will be sensible to both catchment export of organic carbon and to the ongoing eutrophication of the Baltic Proper.     

Design of tyre force excitation for tyre–road friction estimation

Knowledge of the current tyre–road friction coefficient is essential for future autonomous vehicles. The environmental conditions, and the tyre–road friction in particular, determine both the braking distance and the maximum cornering velocity and thus set the boundaries for the vehicle. Tyre–road friction is difficult to estimate during normal driving due to low levels of tyre force excitation. This problem can be solved by using active tyre force excitation. A torque is added to one or several wheels in the purpose of estimating the tyre–road friction coefficient. Active tyre force excitation provides the opportunity to design the tyre force excitation freely. This study investigates how the tyre force should be applied to minimise the error of the tyre–road friction estimate. The performance of different excitation strategies was found to be dependent on both tyre model choice and noise level. Furthermore, the advantage with using tyre models with more parameters decreased when noise was added to the force and slip ratio.     

The design of liner shipping serives: the problem of feeder services versus multi-port-calls

In this paper, the authors outline the structure of liner shipping systems with special emphasis on the question of whether feeder services are superior in economic terms to the more traditional and commonly-used multi-port-calling system. They describe the theoretical advantages of the former over the latter, and develop a model by which the optimal conditions both operate in may be determined. This model is then applied to a real situation to ascertain whether the theory works in practice. They conclude that the shuuttle/feeder system is worthwhile only in exceptional circumstances when specific route characteristics—low trade density; hinterland generated cargo; inland position of port; and heavy congestion—coexist. Despite the expense of multi-port-calling, it remains the most practical solution to the thin trade problem.     

Analysing the effect of trip satisfaction on satisfaction with the leisure activity at the destination of the trip,in relationship with life satisfaction

Transportation - Previous studies have indicated that positive (or negative) experiences of activity episodes are likely to correlate with positive (or negative) evaluations of a persons’...     

A cost–benefit analysis of the Stockholm congestion charging system

This paper presents a cost–benefit analysis of the Stockholm congestion charging system, based on the observed rather than on the model-forecasted data. The most important data sources are travel time and traffic flow measurements made in the year before the charges were introduced (during April 2005) and during the first spring with the charges (during April 2006, 4 months after the charges were introduced). Using matrix calibration, effects on the non-observed link flows and travel times are extrapolated, enabling us to calculate the social value of changes in travel times and travel costs. Impacts on traffic safety and emissions are calculated using standard Swedish CBA relationships. The system is shown to yield a significant social surplus, well enough to cover both investment and operating costs, provided that it is kept for a reasonable lifetime: investment and startup costs are “recovered” in terms of social benefits in around 4 years.     

How does purchasing intangible services online influence the travel to consume these services? A focus on a Chinese context

Transportation - A considerable number of empirical studies have explored the effects of information & communication technologies (ICT) on travel in recent years. In particular, the most...     

Do changes in the residential location lead to changes in travel attitudes? A structural equation modeling approach

Transportation - Numerous studies have found that travel attitudes might not only affect travel behavior, but also the residential location choice as people might choose a residential location...     

Improving the coexistence of offshore wind farms and shipping: an international comparison of navigational risk assessment processes

The continued growth and evolution of the offshore wind industry, and the emergence of other novel marine uses such as wave and tidal generators, have upped the ante for spatial planners, as well as consenting and approval authorities in various coastal states. These stakeholders rely on processes such as navigational risk assessments (NRAs) to balance safety and efficiency requirements and to make optimal decisions over use of space. Given the increasingly complex and crowded seascape, however, there are some apprehensions about potential shortcomings in these NRA processes. There is also some concern that these inadequacies may lead to unsafe or inefficient marine spatial use. To understand how NRA processes can be improved further, a literature review is conducted, followed by a survey of respondents who are involved in the planning, consenting and/or approval of offshore wind farms across seven different countries. A summary of the NRA processes in these seven countries is presented, and several shortcomings are identified. Based on the findings of the survey, a list of recommendations is presented to enhance existing NRA processes—and to improve the coexistence of shipping and offshore wind farms (OWFs).     

The Stockholm congestion – charging trial 2006: Overview of effects

The Stockholm congestion charging trial in 2006 demonstrated the effects of a full-scale time-differentiated urban road toll scheme. Improvements in travel times were large enough to be perceived by the general public. This was pivotal to the radical change of public attitudes that occurred during the trial and that resulted in a positive outcome of a subsequent referendum on a proposal for making the system permanent. This paper summarises the effects of the trial and analyses to what extent targets were met. Effects on congestion reduction were larger than anticipated, which also resulted in favourable economic and environmental effects. The trial showed that a single-cordon toll could affect traffic within a large area, i.e., not just close to the zone limits.