High-Speed System for Rail Condition

The developing high-speed traffic and the increasing number of train-pairs result in the higher track occupancy rate which in turn requires the higher speed of ultrasonic inspection. However, it is commonly known that the speed increase leads to a less stable acoustic contact. Hence, the reliability of inspection is reduced. 

It has been traditionally believed that the ultrasound inspection is limited by the maximum allowable speed and this threshold cannot be exceeded. However, using the extensive experience in the design and manufacture of mobile NDT equipment, in 2013 the specialists of TVEMA developed a unique high-speed system for inspection of rail condition.

For the first time, NDT equipment has been mounted on the carriage equipped with bolsterless bogies manufactured by OAO Tverskoy Vagonostroitel’nyi Zavod (Tver Carriage-building Factory). The SPRINTER inspection vehicle is designed for diagnostics of rails laid in a railway track with 1520 (1524) mm gauge and provides detection and logging of rail defects using ultrasonic non-destructive testing method at speeds up to 140 km/h without compromising the inspection reliability.

The high-speed system for ultrasonic inspection of rail condition comprises:

• mechanical part;

• two multichannel NDT analyzers ECHOCOMPLEX;

• dedicated software;

• ASTRA software for automatic analysis of NDT&TD data.

Mechanical part

The mechanical part of the system is mounted directly on the vehicle bogie. 

The modifications to the design of all major components of the systems yielded unprecedented performance of the solution. These include:

• contactless magnetic tracking system;

• probe system;

• pneumatic system;

• contact fluid supply system, etc. 

Contactless tracking system

The system provides precise positioning of the probe system relative to the rail head through interaction of magnetic fields of the permanent magnets of the system with the field of the magnetized rail.

The advantages of this type of tracking systems are as follows:

• exclusion of mechanical contact of the tracking system with a rail, which could entail appearance of acoustic

interference and reduce the life of the tracking system;

• minimizing the effect of the tracking system on the condition of rail head working surface;

• prevention of acoustical contact loss due to ejection of snow or other contaminants (e.g. products of the rail lubricator) in front of the probe system;

• unhampered passing of switches of any design;

• the possibility of increasing inspection speed. 

Multi-channel NDT analyzer ECHO-COMPLEX-2 

The outstanding feature of the NDT analyzer and the software it controls is the increased number of ultrasonic channels. The innovative hardware solutions implemented in the NDT analyzer and a broad range of functions of the control software offer a new inspection technology which radically reduces the impact of unstable acoustic

contact and the qualification of the decoder on the inspection results. This solution has finally overcome the inspection speed limit previously unattainable for the ultrasound inspection systems. 


Parameter value

Track gauge, mm


Maximum speed, km/h:

• design

• inspecting




Minimum curve radius, m


Overall dimensions, mm

• coupled length

• width (at observation window level)



3104 (+3; -7)

Power unit, type

• power (total), kW, not less than

single-phase diesel generator


Number of ultrasonic channels


Threshold limit value of absolute measurement error for the signal amplitude ratio at the receiver input for separate/combined channels (linearity of receiver attenuator) in the range 15 to 45 dB, not less than



Electric pulse frequency for drive pulse generator, Hz

100 … 4800

Gain range for ultrasonic channels, dB

0 … 96

Continuous operation time during inspection, hours, not less than



Power consumed by NDT vehicle consumers

shall be:

• supplied from diesel generator, kW, not more than

• supplied from external source, kW, not more than