Development of a system to obtain vertical track geometry measuring axle-box accelerations from in-service trains

Nowadays, metropolitan railway systems are in great demand, so they offer highfrequency services for the most part of the day. Therefore there are only a few hours available at night to carry out maintenance tasks. This research develops a system that records vertical accelerations undergone by the bogies of in-service railway vehicles. As accelerations are measured during regular services of trains, no additional vehicles or personnel are needed and maintenance planning is optimized. Accelerations are processed to obtain vertical track alignment in order to determine whether the track needs repair. The developed system has been validated by comparing its results to the actual state of the track provided by a track monitoring trolley. Comparison is performed by using both graphical and statistical methods. Real data was obtained from measurements taken on Line 1 of the Alicante tram network (Spain). This paper presents procedure for data collection, its mathematical processing and analysis in order to identify track condition.