Abstract Article 1: Pressure variations on a train - where is the threshold to discomfort?

The implementation of recent guidelines for tunnel construction in Germany leads to extended air pressure variations inside trains and reduces pressure comfort for railway passengers. A questionnaire survey with 262 passengers revealed that pressure variations are rated less important for riding comfort than climatic and spatial aspects (study 1). A laboratory experiment (study 2) in the pressure chamber at the DLR Institute of Aerospace Medicine with 31 subjects (mean age = 37.7, SD = 12.7; 51.6% male) investigated the effects of systematic pressure variations on discomfort. The pressure changes (pressure increases and decreases) ranged from 1 to 100 mbar and were realized within 1 to 100 s. We derived thresholds for healthy passengers by means of random effects linear and logistic regression analysis. Logistic dose-response curves revealed amplitude/time combinations leading to a certain percentage of passengers perceiving discomfort (e.g. 50% dissatisfied passengers regarding a pressure increase of approximately 30 mbar within 5 s). The findings may help design engineers to meet passengers’ comfort requirements.

Abstract Article 2: Continuous assessments of pressure comfort on a train - A field-laboratory comparison

Pressure variations on a train predominantly occur while trains are passing through tunnels. These aerodynamic effects may give rise to aural discomfort in railway passengers. We conducted a field study on the high speed railway track Cologne-Frankfurt/Main as well as a simulation study in our pressure chamber TITAN (DLR-Institute of Aerospace Medicine) with 31 subjects (mean age = 37.7, SD = 12.7; 51.6% male) to investigate pressure comfort for passengers. Continuous assessments of pressure events using sliders and retrospective assessments were acquired. Pressure variations were mostly tolerated. A comparison of field and laboratory setting revealed high congruency of continuous as well as retrospective assessments. A generalized estimating equation model identified pressure change attributes contributing to passengers’ discomfort. Beside attributes of instantaneous pressure changes (e.g. high amplitudes, short durations), pressure events of the recent past significantly influenced current discomfort. Design engineers may use these findings to improve train and tunnel design.