The presence of common costs does not raise the same theoretical problem for marginal-cost pricing because no arbitrary allocation of these costs is technically necessary. However, problems might be encountered because marginal cost can only be determined with large blocks of output such as a trainload or even a truckload. The output unit to priced can be smaller with LTL shipments. There are some additional problems of a more practical nature, however, with respect to strict marginal-cost pricing.