Sieving Error from Dry-Separating Silt-Sand-Gravel Soils

The dry-separation method is an alternative to the wet-preparation in the current European Standard for the determination of particle size distributions by the sieving of soils. Due to the risk of error, dry-separation is cautioned against in the standard;however, there is no additional guidance as to when it is unsuitable nor for the magnitude of error that it may introduce. This study investigates the dry-separation method as an alternative by comparing with the conventional method of Wet-preparation in terms of particle-size distributions of eight cohesionless sand-gravel soils with varying amounts of nonplastic fines. The findings indicate a gradually increasing sieving error for fractions at minus 0.5 mm with the amount of fines in the soil, and depending on the fines content of the soil, dry-separation introduced errors upwards of 45% in silt-sand-gravel soils. An empirical best-fit formula is proposed for the estimation of the error using the dry-preparation method on this type of soil. Furthermore, to avoid sieving errors, the results suggest that the dry-separation method should not be used for silt-sand-gravel soils exceeding 2% silt size fractions.

European Research Project’s Contributions to a Safer Automated Road Traffic

Automated driving is poised to become a pivotal technology in the future automotive transportation.However,it is evident that the implementation of automated driving presents significant technical challenges.To accelerate the development and deployment of automated driving the European Commission initiated the research project L3Pilot in 2017.With a budget of 65 million Euros and the involvement of 13 car manufacturers,L3Pilot stands as the largest European project on automated driving(AD).This paper serves as a comprehensive account of BMW’s main activities in the L3Pilot project that ended in 2021.The research questions addressed in this project are related to the following topics:what are the guidelines for the development of AD?How do potential customers interact with AD?And what is the safety impact assessment of AD?The paper presents the findings related to all three research questions to contribute to the further development of automated driving.For this purpose together with other partners the Code of Practice of AD was defined as a guideline for the development of future AD systems.Related to the second question,BMW conducted tests with AD systems on motorways and in parking scenarios,with over 100 test subjects experiencing AD.The studies provide input and considerations for future AD systems.Finally,in the safety impact assessment,BMW investigated with other project partners the potential safety benefits of AD through simulation.The results show a potential to improve road safety.In conclusion,the exploration of all three research questions has led to a deeper understanding of SAE Level 3 AD.