The effect of two trains passing at the same time on the ground borne vibration level

When predicting the ground borne vibration level, it is assumed that only one train passes so the predicted vibration level is caused by a single train. When there is one track for every direction of the train, it is possible that two trains will pass each other on a specific location at the same time. What influence do these two trains have on the vibration level compared to the vibration level of a single train passing that same location? For this study ground borne vibration levels have been measured on two locations in The Netherlands using a 3 by 3 grid, 25 meters apart, on a distance of 25, 50 and 75 meters of the track. During the 4 weeks measuring time, all the trains have been captured on video. All the double train situations have been marked. The corresponding vibration level Vmax (according to the Dutch SBR B guideline) has been determined for both the single trains and the double trains and compared to each other. In the analysis, the type of trains passing each other and the distance of the receiver to the track, has been taken into account when determining the difference in vibration level.