Long-span cable trays can safely span bridges or roadways using specially designed trays and supports, with spans typically ranging from 20 to 40 feet depending on load and material.

Types of Cable Trays for Long Spans

Cable trays suitable for bridge spans include:

• Tray-type cable trays: Lightweight, versatile, and suitable for power and instrumentation cables; often used in industrial and commercial applications .
• Ladder-type cable trays: Ideal for large-diameter power cables, offering excellent ventilation and cooling, and suitable for high and low voltage applications .
• Long-span aluminum trays: Extruded aluminum trays with H-beam side rails provide high strength-to-weight ratios and corrosion resistance, allowing spans up to 40 feet with minimal supports .

Support Spacing and Structural Considerations

• Support span is the distance between supports; for long-span trays, this can exceed 20 feet and reach up to 40 feet for outdoor or bridge crossings .
• Tray strength must be designed according to the selected support span, as deflection increases with longer spans .
• Splice plates connect tray sections and should generally be placed only once between supports to maintain structural integrity .
• Material selection: Aluminum is preferred for long spans due to its high strength-to-weight ratio and corrosion resistance, while steel may be used for heavier loads .

Installation Best Practices

• Ensure the tray length matches or exceeds the support span to control splice locations and reduce stress points .
• Use suspended supports, wall brackets, or center suspensions to attach trays to the bridge structure securely .
• Consider environmental factors such as wind, snow, and temperature changes, which can affect tray deflection and expansion .
• For outdoor installations, corrosion-resistant coatings or materials are recommended to extend service life .

Applications

Long-span cable trays are commonly used for:

• Bridge crossings and roadway overpasses
• Industrial plants with long straight cable runs
• Oil, gas, and mining facilities where reducing the number of supports lowers installation costs By selecting the appropriate tray type, material, and support spacing, cable trays can safely and efficiently span bridges while maintaining structural integrity and reliable cable management.