Question

In most cities, hard rubber and plastic materials that easily give in or dent are placed along the center of busy streets as barriers. why is this so?

Answer 1

My guess is it has to do with taking the brunt of impact.
@LastDayWork

Answer 2

Yea...you are right @roadjester :)

Materials "...that easily give in or dent..." will provide a weaker impulse force for a longer duration of time; and hence prevent/reduce injuries.

Answer 3

thank you :)