What is the rule of thumb for building a stable cribbing base?

• A. Use wooden sticks only.
• B. Stack blocks randomly without alignment.
• C. Use a single heavy block at each corner.
• D. Create a broad, square, multi-layer base with blocks arranged securely to prevent slipping.

Answer: (D)

A stable cribbing base hinges on creating a broad, square, multi-layer arrangement where each block is tightly aligned and interlocked to resist slipping. The broad footprint increases contact with the ground, reducing bearing pressure and helping friction hold the blocks in place as the load from the vehicle settles. A square layout aligns with the typical direction of forces, minimizing the chance of tipping or shifting in any direction. Building up multiple layers and interlocking them ties the pieces together so they act as a single rigid unit rather than separate blocks that can slide or collapse. Ensuring each layer is placed securely with minimal gaps and with blocks flush against one another creates a solid, stable foundation that won’t shift when weight is applied.

Using only wooden sticks lacks the mass, surface area, and interlocking capability needed to support heavy loads. Stacking blocks randomly without proper alignment creates gaps and weak points where the base can deform or slip. Placing a single heavy block at each corner leaves large gaps and does not form a continuous, locked structure, so the base can spread or rotate under load.