Evaluating tie support at railway bridge transitions

This paper compares the behavior of three different railway bridge transition zones to illustrate how poor tie support affects track performance. The three bridge transitions consist of a high-speed passenger line, a freight line, and a spur track. All bridge transitions were instrumented with accelerometers that allow tie support and track performance to be non-invasively evaluated by analyzing the measured acceleration magnitudes and vibration frequencies in the frequency domain. The results show tracks with good tie support display tie accelerations below 5 g and small vertical displacements during train loading whereas approaches with poor tie support display accelerations generally greater than 5 g. These results are used to evaluate other transition zones and identify problematic track locations that require repair procedures to retain acceptable track geometry.