Road network and GPS tracking with data processing and quality assessment

GPS technology has been embedded into portable, low-cost electronic devices nowadays to track the movements of mobile objects. This implication has greatly impacted the transportation field by creating a novel and rich source of traffic data on the road network. Although the promise offered by GPS devices to overcome problems like underreporting, respondent fatigue, inaccuracies and other human errors in data collection is significant; the technology is still relatively new that it raises many issues for potential users. These issues tend to revolve around the following areas: reliability, data processing and the related application. This thesis aims to study the GPS tracking form the methodological, technical and practical aspects. It first evaluates the reliability of GPS based traffic data based on data from an experiment containing three different traffic modes (car, bike and bus) traveling along the road network. It then outline the general procedure for processing GPS tracking data and discuss related issues that are uncovered by using real-world GPS tracking data of 316 cars. Thirdly, it investigates the influence of road network density in finding optimal location for enhancing travel efficiency and decreasing travel cost. The results show that the geographical positioning is reliable. Velocity is slightly underestimated, whereas altitude measurements are unreliable.Post processing techniques with auxiliary information is found necessary and important when solving the inaccuracy of GPS data. The densities of the road network influence the finding of optimal locations. The influence will stabilize at a certain level and do not deteriorate when the node density is higher.

On processing GPS tracking data of car-movements in Borlänge, Sweden

The advancement of GPS technology enables GPS devices not only to be used as orientation and navigation tools, but also to track travelled routes. GPS tracking data provides essential information for a broad range of urban planning applications such as transportation routing and planning, traffic management and environmental control. This paper describes on processing the data that was collected by tracking the cars of 316 volunteers over a seven-week period. The detailed information is extracted. The processed data is further connected to the underlying road network by means of maps. Geographical maps are applied to check how the car-movements match the road network. The maps capture the complexity of the car-movements in the urban area. The results show that 90% of the trips on the plane match the road network within a tolerance.

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.

L1 Use in the EFL-classroom : A Literature Review on Teachers’ Use of the L1 in the EFL-classroom on Upper Secondary Level

Even though English should mainly be used in the EFL-classroom according to the Swedish national curriculum, some recent scholars have argued that a judicious use of the students’ L1 by the teachers in some particular situations may benefit the learning environment there. From this context, this thesis examines what research says about in what particular situations the L1 is used by teachers in upper secondary EFL-classrooms as well as the teachers’ and the students’ attitudes towards this practice. The method used was a systematic literature review, where seven articles from all across the globe were analyzed, compared and synthesized. The results show that the L1 was mainly used by the teachers when managing discipline, when explaining grammar and when teaching vocabulary. However, the articles did not conclude how the L1 could be used strategically by the teachers. Concerning the teachers’ and students’ attitudes, the majority of these were positive towards L1 use by the teacher in the above mentioned situations. However, the teachers were not aware of how the L1 could be used by them in a judicious and a strategic way. Lastly, it can be concluded that more research is needed on how the L1 can be used more strategically by the teachers as well as on the students’ perspective on this.

Using Swedish in the EFL-classroom : An Interview Study on Swedish Upper Secondary Students’ Attitudes towards Teachers’ L1 use in the EFL-classroom

There is very little focus in previous research on first language (L1) use by teachers in the upper secondary English as a foreign language (EFL) classroom from the students’ perspective. In this context and from a Swedish perspective, this thesis examines what attitudes students in the Swedish upper secondary school have towards their teachers’ use of L1 (Swedish) in the EFL-classroom. The method used was qualitative semi-structured interviews, where nine students in total were interviewed. The collected data was then coded, thematized and categorized. The results show that the students mainly believed Swedish should be used when teaching vocabulary, when teaching grammar and for classroom management. They did not believe the L1 should be used by them in questions and answers and in general talk in the classroom. They also endorsed an overall judicious use of Swedish by their teachers and that their use of this language should be adjusted to the specific teaching group. Finally, it can be concluded that further research is needed on how the L1 can be used judiciously in particular situations and on what attitudes students of varying proficiency and age, as well as students who do not have Swedish as their L1 have towards teachers’ L1 use in the EFL-classroom.