In the description of designingbyfunction what would you use

In the description of designing-by-function what would you use for a range of required factors of safety for the following situations:

a. A highway underdrain in the shoulder area of a secondary road

b. A filter fabric behind a retaining wall, above which is a paved parking lot

c. A reinforcing fabric for an access road for construction equipment

d. A filter to protect a chimney drain within an earth dam where a small town is located downstream

Solution

a. A highway underdrain in the shoulder area of a secondary road

There is a difference between structural design and functional design. Normally, structural design take care of loads which are applied on structure.

Usage and function of any structure or road depends on its functional design. If functional design is good the performance of that structure also in a good condition. Poor functional design will decrease the efficiency and effectiveness of any structure permance or usage.

So, in this question if the road is wide enough for shoulders and other cross sectional elements then vehicles can also use that space while transportation.