Reliability of GPS based traffic data: an experimental evaluation

GPS tracking of mobile objects provides spatial and temporal data for a broad range of applications including traffic management and control, transportation routing and planning. Previous transport research has focused on GPS tracking data as an appealing alternative to travel diaries. Moreover, the GPS based data are gradually becoming a cornerstone for real-time traffic management. Tracking data of vehicles from GPS devices are however susceptible to measurement errors – a neglected issue in transport research. By conducting a randomized experiment, we assess the reliability of GPS based traffic data on geographical position, velocity, and altitude for three types of vehicles; bike, car, and bus. We find the geographical positioning reliable, but with an error greater than postulated by the manufacturer and a non-negligible risk for aberrant positioning. Velocity is slightly underestimated, whereas altitude measurements are unreliable.

Young peoples’ entrance to the workplace : Introduction to occupational health and safety

Negative outcomes of a poor work environment are more frequent among young workers. The aim of the current study was to study former pupils’ conditions concerning occupational health and safety by investigating the workplaces’, safety climate, the degree of implementation of SWEM and the their introduction programs. Four branches were included in the study: Industrial, Restaurant, Transport and Handicraft, specialising in wood. Semi-structured dialogues were undertaken with 15 employers at companies in which former pupils were employed. They also answered a questionnaire about SWEM. Former pupils and experienced employees were upon the same occasion asked to fill in a questionnaire about safety climate at the workplace. Workplace introduction programs varied and were strongly linked to company size. Most of the former pupils and experienced employees rated the safety climate at their company as high, or good. Employers in three of the branches rated the SWEM implemented at their workplaces to be effective. The Industry companies, which had the largest workplaces, gave the most systematic and workplace introduction for new employees. There are no results from this study explaining the fact that young workers have a higher risk for workplace accidents.