This study presents the transmission of SARS-CoV-2 in the main types of public transport vehicles and stations to comparatively assess the relative theoretical risk of infection of travelers. The presented approach benchmarks different measures to reduce potential exposure in public transport and compares the relative risk between different means of transport and situations encountered. Hence, a profound base for the selection of measures by operators, travelers and staff is provided. Zonal modeling is used as the simulation method to estimate the exposure to passengers in the immediate vicinity as well as farther away from the infected person. The level of exposure to passengers depends on parameters such as the duration of stay and travel profile, as well as the ventilation situation and the wearing of different types of masks. The effectiveness of technical and behavioral measures to minimize the infection risk is comparatively evaluated. Putting on FFP2 (N95) masks and refraining from loud speech decreases the inhaled viral load by over 99%. The results show that technical measures, such as filtering the recirculated air, primarily benefit passengers who are a few rows away from the infected person by reducing exposure 84–91%, whereas near-field exposure is only reduced by 30–69%. An exception is exposure in streetcars, which in the near-field is 17% higher due to the reduced air volume caused by the filter. Thus, it can be confirmed that the prevailing measures in public transport protect passengers from a high theoretical infection risk. At stations, the high airflows and the large air volume result in very low exposures (negligible compared to the remaining means of transport) provided that distance between travelers is kept. The comparison of typical means of transport indicates that the inhaled quanta dose depends primarily on the duration of stay in the vehicles and only secondarily on the ventilation of the vehicles. Due to the zonal modeling approach, it can also be shown that the position of infected person relative to the other passengers is decisive in assessing the risk of infection.
Current developments to implement the More Electric Aircraft (MEA) result in a fundamental change of the aircraft systems architecture. Components may be resized or new components may be introduced. This results in new challenges for the thermal management and safety assessment of systems and therefore parametric and fast simulations tools will become crucial to explore the entire design space. The effects of component heat dissipation on airflow in the aircraft fuselage can be qualified using a zonal simulation model. Zonal airflow models subdivide the indoor space into typically 102 zones exchanging air. This allows to predict the impact of systems locations, ventilation and cooling strategies on the thermal management and safety considerations in an early design stage. This paper presents the setup of such an aircraft zonal model based on high-level requirements for a MEA of regional airplane size. These requirements cover the number of passengers, the flight profile and system components to be integrated, like e.g. the battery. Additional requirements are derived from standards for example providing information on required airflow rates and temperatures in the cabin. These requirements are translated into a geometry, ventilation pattern and systems layout. The model application is demonstrated on the example of the safety consideration in case of a battery failure leading to exhaust of harmful gas. This is done by comparing the gas dispersion for two different battery positions in the aircraft.
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