highway guardrail hot dip galvanized road barrier AASHTO standard type II class A highway guardrail is used to mounting alongside the road,highway to protect vehicles when crash happened.it is through cold forming processing and hot dip galvanizing for corrosion protection. all are according to international standards. highway guardrail hot dip galvanized road barrier AASHTO standard type II class A highway guardrail is used to mounting alongside the road,highway to protect vehicles when crash happened.it is through cold forming processing and hot dip galvanizing for corrosion protection. all are according to international standards.