Long term demand for freight movements in North America is expected to increase dramatically in the coming decades. The railroads are poised to take on this additional traffic assuming the capacity is available. Measuring the capacity of these rail lines is complicated by the interrelationships between asset utilization, reliability, and throughput. There is not a single metric that captures these intricacies. Capacity can be determined by delay-volume relationships, utility models, or economic study. For many case studies, railroads use parametric and simulation modeling to determine the train delay per 100 train miles. This metric does not tell the full story; especially when comparing different train types. The highway industry uses a different portfolio of metrics that can be adopted by railroad capacity planners. These metrics can be more sensitive to the worse performing trains. Additionally, these metrics can control for increased delay simply due to additional traffic. These concepts are illustrated by simulating the impact of additional 110 mph passenger service to a single track freight line.