than 50 miles per hour. All two-lane rural sections, on which the sight distance provided will not permit safe passing at the above design speed for passenger vehicles, shall be appropriately and conspicuously marked as no-passing zones or as zones in which passing is unsafe.
5. All urban sections of the system shall be designed at all points and in all respects for safe travel by passenger vehicles at a speed of not less than 50 miles per hour, and by trucks and tractor combinations at a speed of not less than 35 miles per hour. All urban sections of the system shall provide a sufficient number of lanes and other facilities so that at no time, except during infrequent peak hours, will it be necessary because of the interference of other vehicles to reduce the average running speed to less than 40 miles per hour.
6. Wherever financially feasible, the system shall provide continuous lateral space and adequate support for standing and disabled vehicles of the recommended maximum sizes and weights, clear of the road surface or pavement.
7. All road surfaces, pavements, and structures on the system, when maintained with a reasons expenditure of effort, sha capable of supporting vehicles of the recommended weights without reduction of either weight or speed at any season of the year.
Consistent with the foregoing fundamental recommendations, the Committee proposes for general adoption, basic standards of road and structural design, applicable to the selected interregional highway system. These basic standards are contained in appendix V.
