An engineer in Bulgaria designed a compact drill rig called the Loco Drill for use in underground mines. The Loco Drill is mounted on a locomotive and carried by rail to drilling locations. It was built to drill holes for horizontal mining in tight spaces using mostly Bulgarian-made parts. The Loco Drill has increased drilling productivity over manual drilling and improved worker safety by reducing vibration and noise exposure. Its success is seen as an example of effective collaboration between a mining company and domestic manufacturers.