The most common challenges when moving heavy machinery include access to the site, the weight and size of the machinery, and the need for specialized equipment. Access to the site may be limited due to narrow doorways, low ceilings, or other obstacles. The weight and size of the machinery can make it difficult to transport, and specialized equipment such as cranes, forklifts, and slings may be required. Additionally, many machinery movers in California are experienced in navigating these challenges and can provide the necessary expertise.