$2\mathrm{.}3$ A newly constructed road has been identified to cause unacceptable noise on nearby building. You have been tasked to plan a noise barrier wall. Briefly explain four design aspects you will consider for the barrier design.

$2\mathrm{.}4$ Briefly explain measures you would take to mitigate the effect of erosion for a box culvert that pass beneath the embankment of a rural road in KZN$.$ Also, explain the implication$($s$)$ if erosion is not taken care of for the road thereof.