Different railroad operators have different methods of inspection. The most widely used is manual inspection, where the gang man inspects approximately five to six kilometers per day. With technology evolution, a few railroads have moved on to using trolleys for visual inspection. Typically, these trolleys are driven by a small gas engine to provide speeds up to 25 kmph. Once a defect is identified, the inspector documents the defect and the milepost along with other relevant information in the logbook. The documented defects are then passed on to the maintenance engineer in-charge of that section, who then schedules the repairs. The repair schedule is prioritized based on the severity of the defect. This manual inspection, data transfer, and scheduling increase the time to repair as well as the the risk of derailment.
As the inspection is manual, the track length covered per day is minimal and there is a high possibility of defects going undetected.
In recent years, the market has introduced new products that use electronic sensors to scan track defects at higher speeds. However, most of the applications are for Track Geometry. Surface Defect Scanners are separate equipments that run at lower speeds.
Today, modern railroad operators need high-speed Surface Defect Scanners with robust detection techniques.