MetroTrolley is a battery electric vehicle developed in response to zero emission rail car requirements in certain environments. Its aim is to replace the RRV Hirail-type road-rail vehicle used for ultrasonic rail flaw detection (RFD / non-destructive testing). Previous trolley types do not have full rail inspection capabilities or do not have zero emissions. It was developed in 2007 by the Centre for Advanced Transport Engineering and Research (CATER) in Western Australia primarily for ultrasonic rail flaw detection.
A newly developed alternative is the HANDWave DRT (Dual Rail Tester) which is capable of ultrasonic rail flaw detection performance equivalent to current rail bound testers. This unit can be separated into two separate Single Rail Testers (HANDWave SRT) or towed behind a rail vehicle.