Ratio of Flow to Capacity (RFC) is a term used in Transport Modelling to assess the operation of a junction.  Sometimes known as Reference Flow to Capacity ratio, the result provides an indication of likely junction performance, with a value of 1 implying that the demand flow is equal to the capacity.  Typically a value of 0.85 is seen as the practical capacity, with results higher than this more likely to experience queuing or delay.