What must be done immediately prior to the alignment of rail ends during thermite welding?

Stopping all potential sources of movement or vibration is crucial immediately prior to the alignment of rail ends during thermite welding. This process requires precise alignment to ensure a proper fit and quality weld. Any movement or vibration at this stage can cause misalignment, which could lead to defects in the weld, compromising structural integrity and safety. By ensuring that the area is stable and free from disturbances, the welder can achieve a proper alignment, which is vital for the thermite reaction to take place effectively and create a strong bond between the rail ends.

Other considerations, like moving tools away or preparing materials, are important as well, but they do not directly address the requirement for stability in alignment, which is critical at this phase of the operation.