After moving empty containers with a forklift, an employee began to travel forward in the forklift. While re-entering the main aisle, the left fork struck the roll cage of an oncoming forklift that was travelling in reverse. This caused the injured employee's forklift to tip over onto a guardrail. The upper rail of the guardrail entered the top of the forklift's roll cage, pinning the employee's legs against the seat. The employee sustained a fractured leg.