It is often said that engineering in some form or other has been associated with every step of progress which has been made in New Zealand. This statement is certainly true of the present, and one of the branches which is playing an increasingly important role in national development is highway engineering. Usually we think of highway engineering as one of the branches of civil engineering, but in some projects all branches of engineering are involved – civil, mechanical, electrical, and even electronic. For the purpose of this article, highway engineering is assumed to cover work associated with all public roads.

Road or highway engineering has two important aspects. First, it deals with people's reactions and, secondly, it deals with engineering problems. Closely involved in these two aspects are five basic transportation factors: safety, comfort, time, convenience, and economy.