Freeway projects in both rural and urban areas should be designed to accommodate traffic projections for a 20-year period into the future (mainlanes only). However, some elements (i.e., ramps, direct connections, frontage roads, and collector-distributor roads) may be based on shorter or longer design periods. For additional guidance on the selection of the appropriate periods for forecasting design traffic volumes, see or refer to .

Segments of freeways may be constructed or reconstructed to be proportionate with intermediate traffic demands or with traffic based on the completed system, whichever may be more appropriate.