For the safe and efficient operation of railway lines, regular track surveying and measurement processes must be conducted. These processes ensure the accurate determination of track geometry, including rail gauge, gradient, alignment, and horizontal/vertical positioning. While traditional methods relied on manual measurements, modern surveying operations now utilize advanced, technology-equipped track inspection machines.

Geometric Measurement Machines

These machines check the plan and profile accuracy of the railway track. They are primarily used for inspecting newly laid tracks and identifying sections that require maintenance.

Features:

• Measure alignment, vertical level differences, and curvature along the track axis.
• Utilize sensors based on laser, ultrasonic, and accelerometer technologies.
• Often capable of high-speed measurement (80–160 km/h).
• Output data can be transferred to 3D modeling software.

Example Machine:

• EM-SAT 120 (Plasser & Theurer): A system that can be manually driven or automatically towed.

Track Survey Machine (Generated with the Assistance of Artificial Intelligence)

Ultrasonic and Magnetic Rail Inspection Machines

These machines are used to detect internal cracks, corrosion, and welding defects in rails.

Features:

• Detect internal rail cracks using ultrasonic probes.
• Surface and subsurface defects can be identified using magnetic particle testing.
• Advanced systems include automatic defect marking mechanisms.

Example Machine:

• SPERRY Rail Car (USA): A vehicle equipped with automatic tracking and a defect database.

Vibration and Track Stiffness Measurement Machines

These machines analyze the dynamic behavior of the track by measuring rigidity, track–bed interaction, and vibrations.

Features:

• Used for temporary settlement and relaxation analysis.
• Particularly important for bridge approaches, turnouts, and high-speed lines.
• Supports passenger comfort analysis and maintenance planning.

Example Machine:

• Track Loading Vehicle (TLV): Measures dynamic deformation by applying load to the rail.

Electrical and Signal Monitoring Machines

These machines test whether railway signaling systems are functioning correctly, especially for electromagnetic compatibility (EMC) evaluations.

Features:

• Monitor circuit resistance, signal transmission times, short circuits, and disconnections.
• Test both fiber optic and wired signal systems.
• Record data during line-wide inspections.

High-Speed Measurement Trains

These are integrated test platforms capable of inspecting thousands of kilometers of track at high speeds.

Features:

• Can measure at speeds above 200 km/h.
• Simultaneously analyze rails, sleepers, ballast, and track geometry.
• Often equipped with live video and LiDAR support.

Examples:

• TCDD Measurement Train (Türkiye): The official high-speed inspection train of Türkiye’s railways.
• DB Netz ICE-S (Germany): A test train operated by Deutsche Bahn.

Track Stability and Displacement Measurement Devices

Used to analyze ground settlement and infrastructure degradation, often in conjunction with geotechnical sensors.

Features:

• Produce longitudinal and transverse displacement maps.
• Used for early detection of risks such as flooding or landslides.
• Common technologies include GNSS, InSAR, total stations, and LiDAR-supported analytics.

Areas of Application

• Track Construction: During planning and construction of new railway lines, these machines ensure correct alignment and gradient.
• Maintenance and Repair: Used for regular inspection and early detection of defects on existing lines.
• Safety Audits: Employed in routine inspections to identify potential hazards like gauge deviation or alignment changes.