The following data include 5 cases for northbound trains and 4 cases for southbound trains. The pressures were measured using purpose-built pressure transducers that could be mounted on the train surface and removed without damage to either the train or the transducers. Photographs of the sensors can be found on the train photographs page. |
 Pressure Sensors inside the train |
Tabular data are provided for all 9 cases. Graphical illustrations are provided for one case in each train direction. Data can be found on the following pages:
1. For each case, there are two pressure transducers, one inside the train and one outside. The transducers are at the same location along the train, namely the first coach behind the leading locomotive.
2. For the purposes of the airshaft investigation, only external pressure measurements are relevant. The transducers measured absolute pressures (not gauge pressures) so it is necessary to infer an appropriate “zero” datum shortly before entry to the tunnel.
3. The internal pressures are provided for information only. They demonstrate that the amplitudes of pressure fluctuations inside conventional train coaches are similar to those outside.
4. The pressure transducers were wholly independent. Each was optimised for measuring pressure fluctuations (typically ±1kPa), thereby maximising benefit for the purposes of the present investigation. Note that the data should NOT be used to infer pressure differences between internal and external pressures. This would involve subtracting two large numbers, each subject to uncertainties exceeding the difference between them.
5. For both directions of travel, the pressure histories
include passage through two tunnels. One is Emmerquerung Tunnel. The other
is a short tunnel further south.
