Multiple-axle box acceleration measurements at railway transition zones

•A methodology to monitor transition zones using multi-ABA measurements is proposed.•Four KPIs are proposed to quantify local multi-ABA energy differences.•The method is suitable for multi-ABA systems mounted on operational trains.•Nine double-track railway bridges on the Dutch railway are analyzed. This paper presents a methodology for monitoring transition zones using responses of multiple-axle box acceleration (multi-ABA) measurements. The time–frequency characteristics of the vertical ABA signals from four wheelsets are analyzed. The major contributions are as follows. (1) We propose four key performance indicators (KPIs) to quantify local multi-ABA energy differences at different abutments, tracks, entrance and exit sides, and inner and outer rails. (2) The same dominant spatial frequencies are obtained with different measurement speeds, so the proposed method is suitable for multi-ABA systems mounted on operational trains. Transition zones at nine double-track railway bridges are selected as the case study. The KPIs indicate that (1) the energy differences between abutments are above 80% in three bridges; (2) two abutments show that the energy differences between tracks are higher than 100%; (3) three tracks have energy differences above 100% between the entrance and exit sides; and (4) the energy differences between rails are above 80% on three sides. Finally, using measurement with 7 years of difference, the KPIs and track quality index are discussed. These findings suggest that multi-ABA measurement can be used as a health condition monitoring method for railway transition zones to support condition-based maintenance.