A Microdata Analysis Approach to Transport Infrastructure Maintenance

Maintenance of transport infrastructure assets is widely advocated as the key in minimizing current and future costs of the transportation network. While effective maintenance decisions are often a result of engineering skills and practical knowledge, efficient decisions must also account for the net result over an asset's life-cycle. One essential aspect in the long term perspective of transport infrastructure maintenance is to proactively estimate maintenance needs. In dealing with immediate maintenance actions, support tools that can prioritize potential maintenance candidates are important to obtain an efficient maintenance strategy. This dissertation consists of five individual research papers presenting a microdata analysis approach to transport infrastructure maintenance. Microdata analysis is a multidisciplinary field in which large quantities of data is collected, analyzed, and interpreted to improve decision-making. Increased access to transport infrastructure data enables a deeper understanding of causal effects and a possibility to make predictions of future outcomes. The microdata analysis approach covers the complete process from data collection to actual decisions and is therefore well suited for the task of improving efficiency in transport infrastructure maintenance. Statistical modeling was the selected analysis method in this dissertation and provided solutions to the different problems presented in each of the five papers. In Paper I, a time-to-event model was used to estimate remaining road pavement lifetimes in Sweden. In Paper II, an extension of the model in Paper I assessed the impact of latent variables on road lifetimes; displaying the sections in a road network that are weaker due to e.g. subsoil conditions or undetected heavy traffic. The study in Paper III incorporated a probabilistic parametric distribution as a representation of road lifetimes into an equation for the marginal cost of road wear. Differentiated road wear marginal costs for heavy and light vehicles are an important information basis for decisions regarding vehicle miles traveled (VMT) taxation policies. In Paper IV, a distribution based clustering method was used to distinguish between road segments that are deteriorating and road segments that have a stationary road condition. Within railway networks, temporary speed restrictions are often imposed because of maintenance and must be addressed in order to keep punctuality. The study in Paper V evaluated the empirical effect on running time of speed restrictions on a Norwegian railway line using a generalized linear mixed model.

”En aktiemarknad för alla” : Integritet och marknadsomsorg i (själv)regleringen av den svenska värdepappersmarknaden

”A stock market for all”. Integrity and concern for the market in the (self-)regulation of the Swedish securities market This article deals with the transformation process that led to the substantial growth of the securities markets, and also led to a situation where Sweden became one of the leading countries when it comes to ordinary people investing in shares and mutual funds. The article discusses how social control and regulation of the market changed as a result of this process. A sudden and strong unanimity for knowledge tests in order for a stockbroker to be allowed to conduct brokerage, advisory services and asset management was the significant change in this transformation process. Knowledge tests were first introduced on a voluntary basis by the industry itself, but is now a mandatory requirement by the State. This article argues that the unanimity for knowledge tests best can be understood by studying the broadening of the financial markets. The broadening meant that more groups in society – with very varying capabilities – had started to place their assets in the security markets. They were encouraged to do so since this was considered to be the solution to the growing number of socioeconomic problems. This article is mainly based on market statistics and document analysis supplemented by interviews.