The appropriate design standards must be applied to each construction project consistent with a minimum 20-year design life for highway projects and 75-year design life for highway bridges. The design of TTP projects must take into consideration:

(a) The existing and planned future use of the facility in a manner that is conducive to safety, durability, and economy of maintenance;

(b) The particular needs of each locality, and the environmental, scenic, historic, aesthetic, community, and other cultural values and mobility needs in a cost effective manner; and

(c) Access and accommodation for other modes of transportation.