Why is concrete crash barriers normally used in central divider?

Concrete crash barriers are not considered as the best barrier design because of the following reasons when compared with flexible barriers:

(i) Concrete barriers possess rough surface which, when impacted by moving vehicles, tend to cause considerable damage to the vehicles.

(ii) Since concrete is a rigid material and the deceleration of collided vehicles is comparatively large when compared with flexible barriers.

However, concrete crash barriers have particular application in locations where the deflection of barriers is not allowed. For instance, in the central divider of a carriageway, if flexible barriers are adopted and vehicles crush into the barriers, the deformation resulting from the hitting of vehicles would result in an intrusion to the adjacent carriageway. This is undesirable because this may trigger further collisions in the adjacent carriageway and hence rigid barriers like concrete crash barriers should be adopted in this scenario.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.