Hiroyuki Oneyama

Exploring the use of smartphone accelerometer and gyroscope to study on the estimation of road surface roughness condition

Smartphones are potentially useful to be adopted as a cost-effective and easy to implement tool for the measurement of road surface roughness condition, which is very essential for road monitoring and maintenance planning. In this study, an experiment has been carried out to collect data from accelerometers and gyroscopes on smartphones, which are placed at different locations inside vehicles running on road sections with different roughness conditions. The collected data is processed in the frequency domain to calculate magnitudes of the vibration. It has been revealed that at the considered frequency range of 40–50Hz, there is a very strong relationship between road roughness condition and the magnitudes of vibration, calculated from each axis of the accelerometers and gyroscopes; as well as the average speed. Road roughness condition that is modelled as a linear function of the vibration magnitudes, taking into account of both data from accelerometer and gyroscope as well as the average speed, achieves better estimation than the model that takes into account the magnitude from the accelerometer and the average speed alone. The finding is potentially significant for the development of a more accurate model and a better smartphone app to estimate road roughness condition from smartphone sensors.

Saga of Traffic Simulation Models in Japan

This paper narrates a history of developments in the traffic simulation models in Japan. Starting from 1971, basically two kinds of logic existed for reproducing dynamic traffic flow. These were the Block Density Method and the Input-Output Method. These methods were compared to the calculation engine of the network traffic simulation model. Subsequently, these methods evolved, were modified, and became more advanced as found in the AVENUE and SOUND simulation models. This development catered better to the changes in needs required by newer traffic simulation models and resulted in part from developments in computer technology. The first models do not include drivers’ route choice behaviour, but the later do. Initially these methods were applied to urban expressways; however, they later expanded to include surface street networks.