Each frame consists of a freestanding column topped with a header Service two vehicles with one system Standard trolley-hook height is 22 feet (custom heights available). Standard arm reach distances between six and 12 feet (custom distances available). Column spacing distances up to 50 feet Requires concrete foundations. The system can support one to four workers per side (higher capacity available upon request). Quick and simple field assembly with bolt-together components — no welding required. Enclosed track design decreases the possibility of dirt or dust build-up interfering with trolley travel. Anchor Trolley™ comes standard.