A road barrier transfer machine includes an improved capstan control system that reduces unwanted migration of road barrier spans without requiring inaccurate visual observations and reliance on outdated scripts. The barrier transfer machine includes a moveable chassis, an entry snout, an exit snout, a conveyor system, a capstan system, and the capstan control system. The capstan control system automatically operates the capstan system or provides instructions to an operator of the machine to maintain the tension and compression of a road barrier span within desired ranges to reduce unwanted migration of the span.