How to Prevent Overturning and Collision Accidents

Introduction to RTG Cranes

A Rubber Tired Gantry Crane (RTG) is a mobile container gantry crane used for stacking and transporting containers in ports, rail yards, and intermodal hubs. Known for its mobility and high space utilization, the RTG is currently evolving toward eco-friendly (hybrid/electric) and intelligent (autonomous) upgrades. However, due to its “tire-based movement and high-portal structure,” safety management is paramount.

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I. Core Measures to Prevent Overturning Accidents

Overturning is the most severe risk for an RTG. Main triggers include overloading, eccentric loading, unstable ground, and excessive wind loads.

1. Load Control and Operational Limits

• Strict Load Management: Use overload limiters that trigger an alarm at 90% of the rated capacity and cut power at 110%.
• Avoid Eccentric Loading: Ensure the cargo’s center of gravity aligns with the spreader. Eccentricity should not exceed 5% of the rated load.
• Smooth Operation: Avoid “sudden starts or stops.” Turning speeds must be kept below 3km/h to prevent inertia-driven center-of-gravity shifts.

2. Ground and Equipment Stability

• Ground Bearing Capacity: RTGs must operate on flat, solid ground with a bearing capacity of at least 250kPa. Avoid soft soil or gravel pits.
• Equipment Inspection: Daily checks on tire pressure, leg deformations, and connection bolts are mandatory. Monthly stress tests on the main girder and legs ensure an anti-overturning safety factor of ≥1.5.

3. Wind Load Protection

• Wind Speed Monitoring: Install anemometers. Stop operations if wind speeds exceed 10.8m/s.
• Anchoring Systems: When out of service, use anti-wind wedges, rail clamps, and anchoring devices to secure the crane against high winds (up to 20.7m/s).

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II. Key Measures to Prevent Collision Accidents

Collisions often occur due to blind spots or operational errors involving trucks, personnel, or other cranes.

1. Physical Isolation and Workspace Planning

• Dedicated Lanes: Clearly mark RTG operation zones with a width of at least the “turning radius + 1.5m.”
• Safety Buffers: Maintain a distance of ≥1m from container stacks and ≥3m from buildings/warehouses.

2. Smart Anti-Collision Technology

• Blind Spot Monitoring: Install 360° cameras and millimeter-wave radar or laser sensors. These systems should automatically trigger alarms or reduce speed when obstacles are detected within 5m.
• GPS and TOS Integration: Connect to the Terminal Operating System (TOS) for real-time tracking. If two RTGs come within 10m of each other, the system should notify dispatchers immediately.
• Limit Switches: Use hard limit switches to prevent the trolley or spreader from hitting the portal frame or stack edges.

3. Operational Standardization

• The “Trial Lift” Rule: Before full hoisting, lift the load 30cm off the ground and pause for 5 seconds to check brakes and stability.
• Certified Personnel: Operators and ground commanders must hold valid certifications and use standardized hand signals or radio protocols.

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III. Lifecycle Maintenance and Management

1. Comprehensive Maintenance Schedule

• Daily: Check braking systems, hydraulic leaks, and safety alarms.
• Monthly: Perform weld inspections and verify tire wear.
• Annually: Conduct Static Load Tests (1.25x rated) and Dynamic Load Tests (1.1x rated).

2. Emergency Readiness

Develop emergency plans for “uncontrolled movements in high winds” or “potential tilts.” Conduct quarterly drills to improve the crew’s response to overloads or collision scenarios.

3. IoT and Smart Management

Implement a Smart Monitoring Platform using IoT to collect real-time data on load, wind speed, and position. This allows for “pre-incident intervention” by pushing alerts to management before a tragedy occurs.